liu.seSearch for publications in DiVA
Change search
Refine search result
1234 1 - 50 of 191
CiteExportLink to result list
Permanent link
Cite
Citation style
  • apa
  • harvard1
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • oxford
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf
Rows per page
  • 5
  • 10
  • 20
  • 50
  • 100
  • 250
Sort
  • Standard (Relevance)
  • Author A-Ö
  • Author Ö-A
  • Title A-Ö
  • Title Ö-A
  • Publication type A-Ö
  • Publication type Ö-A
  • Issued (Oldest first)
  • Issued (Newest first)
  • Created (Oldest first)
  • Created (Newest first)
  • Last updated (Oldest first)
  • Last updated (Newest first)
  • Disputation date (earliest first)
  • Disputation date (latest first)
  • Standard (Relevance)
  • Author A-Ö
  • Author Ö-A
  • Title A-Ö
  • Title Ö-A
  • Publication type A-Ö
  • Publication type Ö-A
  • Issued (Oldest first)
  • Issued (Newest first)
  • Created (Oldest first)
  • Created (Newest first)
  • Last updated (Oldest first)
  • Last updated (Newest first)
  • Disputation date (earliest first)
  • Disputation date (latest first)
Select
The maximal number of hits you can export is 250. When you want to export more records please use the Create feeds function.
  • 1.
    Xiong, Sixing
    et al.
    Huazhong Univ Sci and Technol, Peoples R China.
    Hu, Lin
    Huazhong Univ Sci and Technol, Peoples R China.
    Hu, Lu
    Huazhong Univ Sci and Technol, Peoples R China.
    Sun, Lulu
    Huazhong Univ Sci and Technol, Peoples R China.
    Qin, Fei
    Huazhong Univ Sci and Technol, Peoples R China.
    Liu, Xianjie
    Linköping University, Department of Physics, Chemistry and Biology, Surface Physics and Chemistry. Linköping University, Faculty of Science & Engineering.
    Fahlman, Mats
    Linköping University, Department of Science and Technology, Laboratory of Organic Electronics. Linköping University, Faculty of Science & Engineering.
    Zhou, Yinhua
    Huazhong Univ Sci and Technol, Peoples R China.
    12.5% Flexible Nonfullerene Solar Cells by Passivating the Chemical Interaction Between the Active Layer and Polymer Interfacial Layer2019In: Advanced Materials, ISSN 0935-9648, E-ISSN 1521-4095, Vol. 31, no 22, article id 1806616Article in journal (Refereed)
    Abstract [en]

    Nonfullerene (NF) organic solar cells (OSCs) have been attracting significant attention in the past several years. It is still challenging to achieve high-performance flexible NF OSCs. NF acceptors are chemically reactive and tend to react with the low-temperature-processed low-work-function (low-WF) interfacial layers, such as polyethylenimine ethoxylated (PEIE), which leads to the S shape in the current-density characteristics of the cells. In this work, the chemical interaction between the NF active layer and the polymer interfacial layer of PEIE is deactivated by increasing its protonation. The PEIE processed from aqueous solution shows more protonated N+ than that processed from isopropyl alcohol solution, observed from X-ray photoelectron spectroscopy. NF solar cells (active layer: PCE-10:IEICO-4F) with the protonated PEIE interfacial layer show an efficiency of 13.2%, which is higher than the reference cells with a ZnO interlayer (12.6%). More importantly, the protonated PEIE interfacial layer processed from aqueous solution does not require a further thermal annealing treatment (only processing at room temperature). The room-temperature processing and effective WF reduction enable the demonstration of high-performance (12.5%) flexible NF OSCs.

  • 2.
    Amin, Sidra
    et al.
    Lulea Univ Technol, Sweden; Shaheed Benazir Bhutto Univ, Pakistan.
    Tahira, Aneela
    Lulea Univ Technol, Sweden.
    Solangi, Amber
    Univ Sindh, Pakistan.
    Beni, Valerio
    Res Inst Sweden, Sweden.
    Morante, J. R.
    Catalonia Inst Energy Res IREC, Spain.
    Liu, Xianjie
    Linköping University, Department of Physics, Chemistry and Biology, Surface Physics and Chemistry. Linköping University, Faculty of Science & Engineering.
    Fahlman, Mats
    Linköping University, Department of Physics, Chemistry and Biology, Surface Physics and Chemistry. Linköping University, Faculty of Science & Engineering.
    Mazzaro, Raffaello
    Lulea Univ Technol, Sweden.
    Ibupoto, Zafar Hussain
    Lulea Univ Technol, Sweden; Univ Sindh, Pakistan.
    Vomiero, Alberto
    Lulea Univ Technol, Sweden.
    A practical non-enzymatic urea sensor based on NiCo2O4 nanoneedles2019In: RSC Advances, ISSN 2046-2069, E-ISSN 2046-2069, Vol. 9, no 25, p. 14443-14451Article in journal (Refereed)
    Abstract [en]

    We propose a new facile electrochemical sensing platform for determination of urea, based on a glassy carbon electrode (GCE) modified with nickel cobalt oxide (NiCo2O4) nanoneedles. These nanoneedles are used for the first time for highly sensitive determination of urea with the lowest detection limit (1 mu M) ever reported for the non-enzymatic approach. The nanoneedles were grown through a simple and low-temperature aqueous chemical method. We characterized the structural and morphological properties of the NiCo2O4 nanoneedles by TEM, SEM, XPS and XRD. The bimetallic nickel cobalt oxide exhibits nanoneedle morphology, which results from the self-assembly of nanoparticles. The NiCo2O4 nanoneedles are exclusively composed of Ni, Co, and O and exhibit a cubic crystalline phase. Cyclic voltammetry was used to study the enhanced electrochemical properties of a NiCo2O4 nanoneedle-modified GCE by overcoming the typical poor conductivity of bare NiO and Co3O4. The GCE-modified electrode is highly sensitive towards urea, with a linear response (R-2 = 0.99) over the concentration range 0.01-5 mM and with a detection limit of 1.0 mu M. The proposed non-enzymatic urea sensor is highly selective even in the presence of common interferents such as glucose, uric acid, and ascorbic acid. This new urea sensor has good viability for urea analysis in urine samples and can represent a significant advancement in the field, owing to the simple and cost-effective fabrication of electrodes, which can be used as a promising analytical tool for urea estimation.

  • 3.
    Battocchio, Chiara
    et al.
    Roma Tre Univ, Italy.
    Concolato, Sofia
    Roma Tre Univ, Italy.
    De Santis, Serena
    Roma Tre Univ, Italy.
    Fahlman, Mats
    Linköping University, Department of Physics, Chemistry and Biology, Surface Physics and Chemistry. Linköping University, Faculty of Science & Engineering.
    Iucci, Giovanna
    Roma Tre Univ, Italy.
    Santi, Marta
    Roma Tre Univ, Italy.
    Sotgiu, Giovanni
    Roma Tre Univ, Italy.
    Orsini, Monica
    Roma Tre Univ, Italy.
    Chitosan functionalization of titanium and Ti6Al4V alloy with chloroacetic acid as linker agent2019In: Materials science & engineering. C, biomimetic materials, sensors and systems, ISSN 0928-4931, E-ISSN 1873-0191, Vol. 99, p. 1133-1140Article in journal (Refereed)
    Abstract [en]

    In this work, a new covalent grafting of chitosan on titanium and Ti6Al4V alloy surfaces is reported using chloroacetic acid as linker agent. Good results were obtained both on titanium and on Ti6Al4V alloy. The effect of the surface acid pretreatments on the subsequent functionalization with chitosan is evaluated. The morphological aspect of acid etched metal surfaces before chitosan grafting has been characterized by scanning electron microscopy (SEM). The presence of carboxylic groups on metal surfaces and then the efficiency of chitosan covalent immobilization were detected by Fourier transformed infrared-Attenuated Total Reflectance (FTIR-ATR) and X-Ray photoelectron spectroscopy (XPS). Cyclic voltammetry tests, using the functionalized titanium and Ti6Al4V samples as electrodes, were conducted in different aqueous solutions, to detect the presence of the homogeneous overlayer of chitosan on the surface, and to evaluate the importance of the carboxyl groups as linker agent.

  • 4.
    Kiefer, David
    et al.
    Chalmers Univ Technol, Sweden.
    Kroon, Renee
    Chalmers Univ Technol, Sweden.
    Hofmann, Anna I.
    Chalmers Univ Technol, Sweden.
    Sun, Hengda
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, Faculty of Science & Engineering.
    Liu, Xianjie
    Linköping University, Department of Physics, Chemistry and Biology, Surface Physics and Chemistry. Linköping University, Faculty of Science & Engineering.
    Giovannitti, Alexander
    Imperial Coll London, England; Imperial Coll London, England.
    Stegerer, Dominik
    Chalmers Univ Technol, Sweden; Tech Univ Chemnitz, Germany.
    Cano, Alexander
    Chalmers Univ Technol, Sweden.
    Hynynen, Jonna
    Chalmers Univ Technol, Sweden.
    Yu, Liyang
    Chalmers Univ Technol, Sweden.
    Zhang, Yadong
    Georgia Inst Technol, GA 30332 USA; Georgia Inst Technol, GA 30332 USA.
    Nai, Dingqi
    Univ Calif Davis, CA 95616 USA.
    Harrelson, Thomas F.
    Univ Calif Davis, CA 95616 USA.
    Sommer, Michael
    Tech Univ Chemnitz, Germany.
    Moule, Adam J.
    Univ Calif Davis, CA 95616 USA.
    Kemerink, Martijn
    Linköping University, Department of Physics, Chemistry and Biology, Complex Materials and Devices. Linköping University, Faculty of Science & Engineering.
    Marder, Seth R.
    Georgia Inst Technol, GA 30332 USA; Georgia Inst Technol, GA 30332 USA.
    McCulloch, Iain
    Imperial Coll London, England; Imperial Coll London, England; King Abdullah Univ Sci and Technol, Saudi Arabia.
    Fahlman, Mats
    Linköping University, Department of Physics, Chemistry and Biology, Surface Physics and Chemistry. Linköping University, Faculty of Science & Engineering.
    Fabiano, Simone
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, Faculty of Science & Engineering.
    Mueller, Christian
    Chalmers Univ Technol, Sweden.
    Double doping of conjugated polymers with monomer molecular dopants2019In: Nature Materials, ISSN 1476-1122, E-ISSN 1476-4660, Vol. 18, no 2, p. 149-+Article in journal (Refereed)
    Abstract [en]

    Molecular doping is a crucial tool for controlling the charge-carrier concentration in organic semiconductors. Each dopant molecule is commonly thought to give rise to only one polaron, leading to a maximum of one donor: acceptor charge-transfer complex and hence an ionization efficiency of 100%. However, this theoretical limit is rarely achieved because of incomplete charge transfer and the presence of unreacted dopant. Here, we establish that common p-dopants can in fact accept two electrons per molecule from conjugated polymers with a low ionization energy. Each dopant molecule participates in two charge-transfer events, leading to the formation of dopant dianions and an ionization efficiency of up to 200%. Furthermore, we show that the resulting integer charge-transfer complex can dissociate with an efficiency of up to 170%. The concept of double doping introduced here may allow the dopant fraction required to optimize charge conduction to be halved.

  • 5.
    Wang, Chuanfei
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Surface Physics and Chemistry. Linköping University, Faculty of Science & Engineering.
    Ni, Shaofei
    Department of Chemistry, South University of Science and Technology, Shenzhen, China.
    Braun, Slawomir
    Linköping University, Department of Physics, Chemistry and Biology, Surface Physics and Chemistry. Linköping University, Faculty of Science & Engineering.
    Fahlman, Mats
    Linköping University, Department of Physics, Chemistry and Biology, Surface Physics and Chemistry. Linköping University, Faculty of Science & Engineering.
    Liu, Xianjie
    Linköping University, Department of Physics, Chemistry and Biology, Surface Physics and Chemistry. Linköping University, Faculty of Science & Engineering.
    Effects of water vapor and oxygen on non-fullerene small molecule acceptors2019In: Journal of Materials Chemistry C, ISSN 2050-7526, E-ISSN 2050-7534, Vol. 7, no 4, p. 879-886Article in journal (Refereed)
    Abstract [en]

    Due to the rapid development of non-fullerene acceptors (NFAs), the efficiency of organic solar cells is steadily being improved. The stability of organic solar cells also is expected to be enhanced with the introduction of the NFAs, yet the stability of NFAs themselves have been less investigated to date. In this paper, the stability of a set of typical NFAs was studied in situ employing photoelectron spectroscopy. The studied molecules show higher resistance to water vapor and thermal stress compared to fullerenes. For water vapor exposure, the highest occupied molecular orbital (HOMO) of NFAs undergoes only minor and reversible changes and the NFAs/substrate work function stays constant. Exposure to oxygen gas significantly modified the electronic structure of the NFAs and the effect was only partially reversible by annealing. However, the presence of water vapor was shown to slow down the degradation caused by oxygen. This is in stark contrast to fullerenes that undergo irreversible degradation upon water vapor exposure.

  • 6.
    Lach, Stefan
    et al.
    Univ Kaiserslautern, Germany.
    Altenhof, Anna
    Univ Kaiserslautern, Germany.
    Shi, Shengwei
    Linköping University, Department of Physics, Chemistry and Biology, Surface Physics and Chemistry. Linköping University, Faculty of Science & Engineering. Wuhan Inst Technol, Peoples R China.
    Fahlman, Mats
    Linköping University, Department of Science and Technology, Laboratory of Organic Electronics. Linköping University, Faculty of Science & Engineering.
    Ziegler, Christiane
    Univ Kaiserslautern, Germany.
    Electronic and magnetic properties of a ferromagnetic cobalt surface by adsorbing ultrathin films of tetracyanoethylene2019In: Physical Chemistry, Chemical Physics - PCCP, ISSN 1463-9076, E-ISSN 1463-9084, Vol. 21, no 28, p. 15833-15844Article in journal (Refereed)
    Abstract [en]

    Ultrathin films of tetracyanoethylene (TCNE) on Co(100) were investigated by means of spin-integrated and spin-resolved photoemission spectroscopy ((sp-)UPS), X-ray photoemission spectroscopy (XPS), near edge X-ray absorption fine-structure spectroscopy (NEXAFS), and X-ray magnetic circular dichroism (XMCD). We found a coverage-dependent modulation of the interface dipole and a switching between a metallic and a resistive spin filtering at the interface triggered by two distinct adsorption geometries of TCNE. The strongest hybridization and spin structure modifications are found at low coverage with a face-on adsorption geometry indicating changes in the distance between the surface Co atoms beneath. TCNE has the potential to manipulate the magnetic moments in the Co surface itself, including the possibility of magnetic hardening effects. In summary, the system TCNE/Co offers an experimentally rather easy and controllable way to build up a stable molecular platform stabilizing the reactive ferromagnetic Co surface and customizing the electronic and magnetic properties of the resulting spinterface simultaneously. This makes this system very attractive for spintronic applications as an alternative, less reactive but highly spin polarized foundation beside graphene-based systems.

  • 7.
    Yang, Jianming
    et al.
    East China Normal Univ, Peoples R China.
    Xiong, Shaobing
    East China Normal Univ, Peoples R China.
    Qu, Tianyi
    Soochow Univ, Peoples R China.
    Zhang, Yuexing
    Soochow Univ, Peoples R China.
    He, Xiaoxiao
    East China Normal Univ, Peoples R China.
    Guo, Xuewen
    East China Normal Univ, Peoples R China.
    Zhao, Qiuhua
    East China Normal Univ, Peoples R China.
    Braun, Slawomir
    Linköping University, Department of Physics, Chemistry and Biology, Surface Physics and Chemistry. Linköping University, Faculty of Science & Engineering.
    Chen, Jinquan
    East China Normal Univ, Peoples R China.
    Xu, Jianhua
    East China Normal Univ, Peoples R China.
    L, Yanqing I
    Soochow Univ, Peoples R China.
    Liu, Xianjie
    Linköping University, Department of Physics, Chemistry and Biology, Surface Physics and Chemistry. Linköping University, Faculty of Science & Engineering.
    Duan, Chungang
    East China Normal Univ, Peoples R China; Shanxi Univ, Peoples R China.
    Tang, Jianxin
    Soochow Univ, Peoples R China.
    Fahlman, Mats
    Linköping University, Department of Physics, Chemistry and Biology, Surface Physics and Chemistry. Linköping University, Faculty of Science & Engineering.
    Bao, Qinye
    Linköping University, Department of Physics, Chemistry and Biology, Surface Physics and Chemistry. Linköping University, Faculty of Science & Engineering. East China Normal Univ, Peoples R China; Shanxi Univ, Peoples R China.
    Extremely Low-Cost and Green Cellulose Passivating Perovskites for Stable and High-Performance Solar Cells2019In: ACS Applied Materials and Interfaces, ISSN 1944-8244, E-ISSN 1944-8252, Vol. 11, no 14, p. 13491-13498Article in journal (Refereed)
    Abstract [en]

    The fast evolution of metal halide perovskite solar cells has opened a new chapter in the field of renewable energy. High-quality perovskite films as the active layers are essential for both high efficiency and long-term stability. Here, the perovskite films with enlarged crystal grain size and decreased defect density are fabricated by introducing the extremely low-cost and green polymer, ethyl cellulose (EC), into the perovskite layer. The addition of EC triggers hydrogen bonding interactions between EC and the perovskite, passivating the charge defect traps at the grain boundaries. The long chain of EC further acts as a scaffold for the perovskite structure, eliminating the annealing-induced lattice strain during the film fabrication process. The resulting devices with the EC additive exhibit a remarkably enhanced average power conversion efficiency from 17.11 to 19.27% and an improvement of all device parameters. The hysteresis index is found to decrease by three times from 0.081 to 0.027, which is attributed to suppressed ion migration and surface charge trapping. In addition, the defect passivation by EC significantly improves the environmental stability of the perovskite films, yielding devices that retain 80% of their initial efficiency after 30 days in ambient air at 45% relative humidity, whereas the pristine devices without EC fully degrade. This work provides a low-cost and green avenue for passivating defects that improves both the efficiency and operational stability of perovskite solar cells.

  • 8.
    Bao, Qinye
    et al.
    East China Normal Univ, Peoples R China.
    Braun, Slawomir
    Linköping University, Department of Physics, Chemistry and Biology, Surface Physics and Chemistry. Linköping University, Faculty of Science & Engineering.
    Wang, Chuan Fei
    Linköping University, Department of Physics, Chemistry and Biology, Surface Physics and Chemistry. Linköping University, Faculty of Science & Engineering.
    Liu, Xianjie
    Linköping University, Department of Physics, Chemistry and Biology, Surface Physics and Chemistry. Linköping University, Faculty of Science & Engineering.
    Fahlman, Mats
    Linköping University, Department of Physics, Chemistry and Biology, Surface Physics and Chemistry. Linköping University, Faculty of Science & Engineering.
    Interfaces of (Ultra)thin Polymer Films in Organic Electronics2019In: Advanced Materials Interfaces, ISSN 2196-7350, Vol. 6, no 1, article id 1800897Article, review/survey (Refereed)
    Abstract [en]

    In this short review the energy level alignment of interfaces involving solution-processed conjugated polymer (and soluble small molecules) films is described. Some general material properties of conjugated polymers and their solution-processed films are introduced, and the basic physics involved in energy level alignment at their interfaces is then discussed. An overview of energy level bending in (ultra)thin conjugated polymer films (often referred to as "band bending") is given and the effects of ion-containing interlayers typically used in organic electronic devices such as polymer light emitting diodes and organic bulk heterojunction solar cells are explored. The review finishes by describing a few of the available computational models useful for predicting and/or modeling energy level alignment at interfaces of solution-processed polymer films and discusses their respective strengths and weaknesses.

  • 9.
    Ibupoto, Zafar Hussain
    et al.
    Division of Material Science, Department of Engineering Sciences and Mathematics, Luleå University of Technology, Luleå, Sweden; Dr. M.A Kazi Institute of Chemistry University of Sindh Jamshoro, Sindh, Pakistan.
    Tahira, Aneela
    Division of Material Science, Department of Engineering Sciences and Mathematics, Luleå University of Technology, Luleå, Sweden.
    Tang, PengYi
    Catalan Institute of Nanoscience and Nanotechnology (ICN2), CSIC and BIST, Campus UAB, Bellaterra, Barcelona, Catalonia, Spain; Catalonia Institute for Energy Research (IREC), Jardins de les Dones de Negre 1, Sant Adrià del Besòs, Barcelona, Catalonia, Spain.
    Liu, Xianjie
    Linköping University, Department of Physics, Chemistry and Biology, Surface Physics and Chemistry. Linköping University, Faculty of Science & Engineering.
    Morante, Joan Ramon
    Catalonia Institute for Energy Research (IREC), Jardins de les Dones de Negre 1, Sant Adrià del Besòs, Barcelona, Catalonia, Spain.
    Fahlman, Mats
    Linköping University, Department of Physics, Chemistry and Biology, Surface Physics and Chemistry. Linköping University, Faculty of Science & Engineering.
    Arbiol, Jordi
    Catalan Institute of Nanoscience and Nanotechnology (ICN2), CSIC and BIST, Campus UAB, Bellaterra, Barcelona, Catalonia, Spain; ICREA, Pg. Lluís Companys 23, Barcelona, Catalonia, Spain.
    Vagin, Mikhail
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, Faculty of Science & Engineering.
    Vomiero, Alberto
    Division of Material Science, Department of Engineering Sciences and Mathematics, Luleå University of Technology, Luleå, Sweden.
    MoSx@NiO Composite Nanostructures: An Advanced Nonprecious Catalyst for Hydrogen Evolution Reaction in Alkaline Media2019In: Advanced Functional Materials, ISSN 1616-301X, E-ISSN 1616-3028, Vol. 29, no 7, article id 1807562Article in journal (Refereed)
    Abstract [en]

    The design of the earth-abundant, nonprecious, efficient, and stable electrocatalysts for efficient hydrogen evolution reaction (HER) in alkaline media is a hot research topic in the field of renewable energies. A heterostructured system composed of MoSx deposited on NiO nanostructures (MoSx@NiO) as a robust catalyst for water splitting is proposed here. NiO nanosponges are applied as cocatalyst for MoS2 in alkaline media. Both NiO and MoS2@NiO composites are prepared by a hydrothermal method. The NiO nanostructures exhibit sponge-like morphology and are completely covered by the sheet-like MoS2. The NiO and MoS2 exhibit cubic and hexagonal phases, respectively. In the MoSx@NiO composite, the HER experiment in 1 m KOH electrolyte results in a low overpotential (406 mV) to produce 10 mA cm(-2) current density. The Tafel slope for that case is 43 mV per decade, which is the lowest ever achieved for MoS2-based electrocatalyst in alkaline media. The catalyst is highly stable for at least 13 h, with no decrease in the current density. This simple, cost-effective, and environmentally friendly methodology can pave the way for exploitation of MoSx@NiO composite catalysts not only for water splitting, but also for other applications such as lithium ion batteries, and fuel cells.

  • 10.
    Bai, Sai
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics. Linköping University, Faculty of Science & Engineering. Univ Oxford, England.
    Da, Peimei
    Univ Oxford, England.
    Li, Cheng
    Univ Bayreuth, Germany; Xiamen Univ, Peoples R China.
    Wang, Zhiping
    Univ Oxford, England.
    Yuan, Zhongcheng
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics. Linköping University, Faculty of Science & Engineering.
    Fu, Fan
    Empa-Swiss Federal Laboratories for Materials Science and Technology, Duebendorf, Switzerland.
    Kawecki, Maciej
    Empa, Switzerland; Univ Basel, Switzerland.
    Liu, Xianjie
    Linköping University, Department of Physics, Chemistry and Biology, Surface Physics and Chemistry. Linköping University, Faculty of Science & Engineering.
    Sakai, Nobuya
    Univ Oxford, England.
    Wang, Jacob Tse-Wei
    CSIRO Energy, Australia.
    Huettner, Sven
    Univ Bayreuth, Germany.
    Buecheler, Stephan
    Empa Swiss Fed Labs Mat Sci and Technol, Switzerland.
    Fahlman, Mats
    Linköping University, Department of Physics, Chemistry and Biology, Surface Physics and Chemistry. Linköping University, Faculty of Science & Engineering.
    Gao, Feng
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics. Linköping University, Faculty of Science & Engineering. Univ Oxford, England.
    Snaith, Henry J.
    Univ Oxford, England.
    Planar perovskite solar cells with long-term stability using ionic liquid additives2019In: Nature, ISSN 0028-0836, E-ISSN 1476-4687, Vol. 571, no 7764, p. 245-+Article in journal (Refereed)
    Abstract [en]

    Solar cells based on metal halide perovskites are one of the most promising photovoltaic technologies(1-4). Over the past few years, the long-term operational stability of such devices has been greatly improved by tuning the composition of the perovskites(5-9), optimizing the interfaces within the device structures(10-13), and using new encapsulation techniques(14,15). However, further improvements are required in order to deliver a longer-lasting technology. Ion migration in the perovskite active layer-especially under illumination and heat-is arguably the most difficult aspect to mitigate(16-18). Here we incorporate ionic liquids into the perovskite film and thence into positive-intrinsic-negative photovoltaic devices, increasing the device efficiency and markedly improving the long-term device stability. Specifically, we observe a degradation in performance of only around five per cent for the most stable encapsulated device under continuous simulated full-spectrum sunlight for more than 1,800 hours at 70 to 75 degrees Celsius, and estimate that the time required for the device to drop to eighty per cent of its peak performance is about 5,200 hours. Our demonstration of long-term operational, stable solar cells under intense conditions is a key step towards a reliable perovskite photovoltaic technology.

  • 11.
    Qin, Leiqian
    et al.
    Linköping University, Department of Physics, Chemistry and Biology. Linköping University, Faculty of Science & Engineering.
    Tao, Quanzheng
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Liu, Xianjie
    Linköping University, Department of Physics, Chemistry and Biology, Surface Physics and Chemistry. Linköping University, Faculty of Science & Engineering.
    Fahlman, Mats
    Linköping University, Department of Physics, Chemistry and Biology, Surface Physics and Chemistry. Linköping University, Faculty of Science & Engineering.
    Halim, Joseph
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Persson, Per O A
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Rosén, Johanna
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Zhang, Fengling
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics. Linköping University, Faculty of Science & Engineering. Jinan Univ, Peoples R China.
    Polymer-MXene composite films formed by MXene-facilitated electrochemical polymerization for flexible solid-state microsupercapacitors2019In: Nano Energy, ISSN 2211-2855, E-ISSN 2211-3282, Vol. 60, p. 734-742Article in journal (Refereed)
    Abstract [en]

    Materials with tailored properties are crucial for high performance electronics applications. Hybrid materials composed of inorganic and organic components can possess unique merits for broad application by synergy between the advantages the respective material type offers. Here we demonstrate a novel electrochemical polymerization (EP) enabled by a 2D transition metal carbide MXene for obtaining conjugated polymer-MXene composite films deposited on conducting substrates without using traditional electrolytes, indispensable compounds for commonly electrochemical polymerization. The universality of the process provides a novel approach for EP allowing fast facile process for obtaining different new polymer/MXene composites with controlled thickness and micro-pattern. Furthermore, high performance microsupercapacitors and asymmetric microsupercapacitors are realized based on the excellent composites benefiting from higher areal capacitance, better rate capabilities and lower contact resistance than conventional electropolymerized polymers. The AMSCs exhibit a maximum areal capacitance of 69.5 mF cm(-2), an ultrahigh volumetric energy density (250.1 mWh cm(-3)) at 1.6 V, and excellent cycling stability up to 10000 cycles. The excellent electrochemical properties of the composite polymerized with MXene suggest a great potential of the method for various energy storage applications.

  • 12.
    Xu, Weidong
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics. Linköping University, Faculty of Science & Engineering. Key Laboratory of Flexible Electronics (KLOFE) and Institute of Advanced Materials (IAM), Jiangsu National Synergetic Innovation Center for Advanced Materials (SICAM), Nanjing Tech University (NanjingTech), Nanjing, China.
    Hu, Qi
    Key Laboratory of Flexible Electronics (KLOFE) and Institute of Advanced Materials (IAM), Jiangsu National Synergetic Innovation Center for Advanced Materials (SICAM), Nanjing Tech University (NanjingTech), Nanjing, China.
    Bai, Sai
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics. Linköping University, Faculty of Science & Engineering.
    Bao, Chunxiong
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics. Linköping University, Faculty of Science & Engineering. International Collaborative Laboratory of 2D Materials for Optoelectronics Science and Technology, Shenzhen University, Shenzhen, China.
    Miao, Yanfeng
    Key Laboratory of Flexible Electronics (KLOFE) and Institute of Advanced Materials (IAM), Jiangsu National Synergetic Innovation Center for Advanced Materials (SICAM), Nanjing Tech University (NanjingTech), Nanjing, China.
    Yuan, Zhongcheng
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics. Linköping University, Faculty of Science & Engineering.
    Borzda, Tetiana
    Center for Nano Science and Technology @Polimi, Istituto Italiano di Tecnologia, Milan, Italy.
    Barker, Alex J.
    Center for Nano Science and Technology @Polimi, Istituto Italiano di Tecnologia, Milan, Italy.
    Tyukalova, Elizaveta
    School of Materials Science and Engineering, Nanyang Technological University (NTU), Singapore, Singapore.
    Hu, Zhang-Jun
    Linköping University, Department of Physics, Chemistry and Biology, Molecular Surface Physics and Nano Science. Linköping University, Faculty of Science & Engineering.
    Kawecki, Maciej
    Laboratory for Nanoscale Materials Science, Empa, Dubendorf, Switzerland / Department of Physics, University of Basel, Basel, Switzerland.
    Wang, Heyong
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics. Linköping University, Faculty of Science & Engineering.
    Yan, Zhibo
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics. Linköping University, Faculty of Science & Engineering. Laboratory of Solid State Microstructures and Innovation Center of Advanced Microstructures, Nanjing University, Nanjing, P. R. China.
    Liu, Xianjie
    Linköping University, Department of Physics, Chemistry and Biology, Surface Physics and Chemistry. Linköping University, Faculty of Science & Engineering.
    Shi, Xiaobo
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics. Linköping University, Faculty of Science & Engineering.
    Uvdal, Kajsa
    Linköping University, Department of Physics, Chemistry and Biology, Molecular Surface Physics and Nano Science. Linköping University, Faculty of Science & Engineering.
    Fahlman, Mats
    Linköping University, Department of Physics, Chemistry and Biology, Surface Physics and Chemistry. Linköping University, Faculty of Science & Engineering.
    Zhang, Wenjing
    International Collaborative Laboratory of 2D Materials for Optoelectronics Science and Technology, Shenzhen University, Shenzhen, China.
    Duchamp, Martial
    School of Materials Science and Engineering, Nanyang Technological University (NTU), Singapore, Singapore.
    Liu, Jun-Ming
    Laboratory of Solid State Microstructures and Innovation Center of Advanced Microstructures, Nanjing University, Nanjing, P. R. China.
    Petrozza, Annamaria
    Center for Nano Science and Technology @Polimi, Istituto Italiano di Tecnologia, Milan, Italy.
    Wang, Jianpu
    Key Laboratory of Flexible Electronics (KLOFE) and Institute of Advanced Materials (IAM), Jiangsu National Synergetic Innovation Center for Advanced Materials (SICAM), Nanjing Tech University (NanjingTech), Nanjing, China.
    Liu, Li-Min
    Beijing Computational Science Research Center, Beijing, China / chool of Physics, Beihang University, Beijing, China .
    Huang, Wei
    ey Laboratory of Flexible Electronics (KLOFE) and Institute of Advanced Materials (IAM), Jiangsu National Synergetic Innovation Center for Advanced Materials (SICAM), Nanjing Tech University (NanjingTech), Nanjing, China / Shaanxi Institute of Flexible Electronics (SIFE), Northwestern Polytechnical University (NPU), Xi’an, China.
    Gao, Feng
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics. Linköping University, Faculty of Science & Engineering.
    Rational molecular passivation for high-performance perovskite light-emitting diodes2019In: Nature Photonics, ISSN 1749-4885, E-ISSN 1749-4893, Vol. 13, no 6, p. 418-424Article in journal (Refereed)
    Abstract [en]

    A major efficiency limit for solution-processed perovskite optoelectronic devices, for example light-emitting diodes, is trap-mediated non-radiative losses. Defect passivation using organic molecules has been identified as an attractive approach to tackle this issue. However, implementation of this approach has been hindered by a lack of deep understanding of how the molecular structures influence the effectiveness of passivation. We show that the so far largely ignored hydrogen bonds play a critical role in affecting the passivation. By weakening the hydrogen bonding between the passivating functional moieties and the organic cation featuring in the perovskite, we significantly enhance the interaction with defect sites and minimize non-radiative recombination losses. Consequently, we achieve exceptionally high-performance near-infrared perovskite light-emitting diodes with a record external quantum efficiency of 21.6%. In addition, our passivated perovskite light-emitting diodes maintain a high external quantum efficiency of 20.1% and a wall-plug efficiency of 11.0% at a high current density of 200 mA cm−2, making them more attractive than the most efficient organic and quantum-dot light-emitting diodes at high excitations.

  • 13.
    Li, Guowei
    et al.
    Max Planck Inst Chem Phys Solids, Germany.
    Fu, Chenguang
    Max Planck Inst Chem Phys Solids, Germany.
    Wu, Jiquan
    Linköping University, Department of Physics, Chemistry and Biology, Surface Physics and Chemistry. Linköping University, Faculty of Science & Engineering.
    Rao, Jiancun
    Univ Maryland, MD 20742 USA.
    Liou, Sz-Chian
    Univ Maryland, MD 20742 USA.
    Xu, Xijin
    Univ Jinan, Peoples R China.
    Shao, Baiqi
    Chinese Acad Sci, Peoples R China.
    Liu, Kai
    Chinese Acad Sci, Peoples R China.
    Liu, Enke
    Chinese Acad Sci, Peoples R China.
    Kumar, Nitesh
    Max Planck Inst Chem Phys Solids, Germany.
    Liu, Xianjie
    Linköping University, Department of Physics, Chemistry and Biology, Surface Physics and Chemistry. Linköping University, Faculty of Science & Engineering.
    Fahlman, Mats
    Linköping University, Department of Physics, Chemistry and Biology, Surface Physics and Chemistry. Linköping University, Faculty of Science & Engineering.
    Gooth, Johannes
    Max Planck Inst Chem Phys Solids, Germany.
    Auffermann, Gudrun
    Max Planck Inst Chem Phys Solids, Germany.
    Sun, Yan
    Max Planck Inst Chem Phys Solids, Germany.
    Felser, Claudia
    Max Planck Inst Chem Phys Solids, Germany.
    Zhang, Baomin
    Univ Jinan, Peoples R China.
    Synergistically creating sulfur vacancies in semimetal-supported amorphous MoS2 for efficient hydrogen evolution2019In: Applied Catalysis B: Environmental, ISSN 0926-3373, E-ISSN 1873-3883, Vol. 254Article in journal (Refereed)
    Abstract [en]

    The presence of elemental vacancies in materials are inevitable according to statistical thermodynamics, which will decide the chemical and physical properties of the investigated system. However, the controlled manipulation of vacancies for specific applications is a challenge. Here we report a facile method for creating large concentrations of S vacancies in the inert basal plane of MoS2 supported on semimetal CoMoP2. With a small applied potential, S atoms can be removed in the form of H2S due to the optimized free energy of formation. The existence of vacancies favors electron injection from the electrode to the active site by decreasing the contact resistance. As a consequence, the catalytic current is increased by 221% with the vacancy-rich MoS2 as electrocatalyst for hydrogen evolution reaction (HER). A small overpotential of 75 mV is needed to deliver a current density of 10 mA cm(-2), which is considered among the best values achieved for MoS2. It is envisaged that this work may provide a new strategy for utilizing the semimetal phase for structuring MoS2 into a multi-functional material.

  • 14.
    Guo, Xuewen
    et al.
    East China Normal Univ, Peoples R China.
    Li, Danqin
    East China Normal Univ, Peoples R China.
    Zhang, Yuexing
    Soochow Univ, Peoples R China.
    Jan, Ming
    Shanghai Jiao Tong Univ, Peoples R China.
    Xu, Jinqiu
    Shanghai Jiao Tong Univ, Peoples R China.
    Wang, Zhiquan
    East China Normal Univ, Peoples R China.
    Li, Bo
    East China Normal Univ, Peoples R China.
    Xiong, Shaobing
    East China Normal Univ, Peoples R China.
    Li, Yanqing
    Soochow Univ, Peoples R China.
    Liu, Feng
    Shanghai Jiao Tong Univ, Peoples R China.
    Tang, Jianxin
    Soochow Univ, Peoples R China.
    Duan, Chungang
    East China Normal Univ, Peoples R China; Shanxi Univ, Peoples R China.
    Fahlman, Mats
    Linköping University, Department of Physics, Chemistry and Biology, Surface Physics and Chemistry. Linköping University, Faculty of Science & Engineering.
    Bao, Qinye
    Linköping University, Department of Physics, Chemistry and Biology, Surface Physics and Chemistry. Linköping University, Faculty of Science & Engineering. East China Normal Univ, Peoples R China; Shanxi Univ, Peoples R China; Soochow Univ, Peoples R China.
    Understanding the effect of N2200 on performance of J71: ITIC bulk heterojunction in ternary non-fullerene solar cells2019In: Organic electronics, ISSN 1566-1199, E-ISSN 1878-5530, Vol. 71, p. 65-71Article in journal (Refereed)
    Abstract [en]

    None-fullerene solar cells with ternary architecture have attracted much attention because it is an effective approach for boosting the device power conversion efficiency. Here, the crystalline polymer N2200 as the third component is integrated into J71: ITIC bulk heterojunction. A series of characterizations indicate that N2200 could increase photo-harvesting, balanced hole and electron mobilities, enhanced exciton dissociation, and suppressed charge recombination, which result in the comprehensive improvement of open circuit voltage, short circuit current and fill factor in the device. Moreover, after introduction of N2200, the morphology of the ternary active layer is optimized, and the film crystallinity is improved. This work demonstrates that adding a small quantity of high crystallization acceptor into non-fullerene donor: acceptor mixture is a promising strategy toward developing high-performance organic solar cells.

  • 15.
    Shi, Shengwei
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Surface Physics and Chemistry. Linköping University, Faculty of Science & Engineering. Wuhan Inst Technol, Peoples R China.
    Sun, Zhengyi
    Nanjing Tech Univ, Peoples R China.
    Liu, Xianjie
    Linköping University, Department of Physics, Chemistry and Biology, Surface Physics and Chemistry. Linköping University, Faculty of Science & Engineering.
    Bedoya-Pinto, Amilcar
    CiC NanoGUNE Consolider, Spain.
    Graziosi, Patrizio
    CNR ISMN, Italy.
    Yu, Huangzhong
    South China Univ Technol, Peoples R China.
    Li, Wenting
    Wuhan Inst Technol, Peoples R China.
    Liu, Gang
    Wuhan Inst Technol, Peoples R China.
    Hueso, Luis
    CiC NanoGUNE Consolider, Spain.
    Dediu, Valentin A.
    CNR ISMN, Italy.
    Fahlman, Mats
    Linköping University, Department of Physics, Chemistry and Biology, Surface Physics and Chemistry. Linköping University, Faculty of Science & Engineering.
    11,11,12,12-Tetracyanonaphtho-2,6-quinodimethane in Contact with Ferromagnetic Electrodes for Organic Spintronics2018In: ADVANCED ELECTRONIC MATERIALS, ISSN 2199-160X, Vol. 4, no 7, article id 1800077Article in journal (Refereed)
    Abstract [en]

    Spinterface engineering has shown quite important roles in organic spintronics as it can improve spin injection or extraction. In this study, 11,11,12,12-tetracyanonaptho-2,6-quinodimethane (TNAP) is introduced as an interfacial layer for a prototype interface of Fe/TNAP. An element-specific investigation of the electronic and magnetic structures of Fe/TNAP system by use of near edge X-Ray absorption fine structure (NEXAFS) and X-ray magnetic circular dichroism (XMCD) is reported. Strong hybridization between TNAP and Fe and induced magnetization of N atoms in TNAP molecule are observed. XMCD sum rule analysis demonstrates that the adsorption of TNAP reduces the spin moment of Fe by 12%. In addition, induced magnetization in N K-edge of TNAP is also found with other commonly used ferromagnets in organic spintronics, such as La0.7Sr0.3MnO3 and permalloy, which makes TNAP a very promising molecule for spinterface engineering in organic spintronics.

  • 16.
    Wijeratne, Kosala
    et al.
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, Faculty of Science & Engineering.
    Ail, Ujwala
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, Faculty of Science & Engineering.
    Brooke, Robert
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, Faculty of Science & Engineering.
    Vagin, Mikhail
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, Faculty of Science & Engineering.
    Liu, Xianjie
    Linköping University, Department of Physics, Chemistry and Biology, Surface Physics and Chemistry. Linköping University, Faculty of Science & Engineering.
    Fahlman, Mats
    Linköping University, Department of Physics, Chemistry and Biology, Surface Physics and Chemistry. Linköping University, Faculty of Science & Engineering.
    Crispin, Xavier
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, Faculty of Science & Engineering.
    Bulk electronic transport impacts on electron transfer at conducting polymer electrode-electrolyte interfaces.2018In: Proceedings of the National Academy of Sciences of the United States of America, ISSN 0027-8424, E-ISSN 1091-6490, no 7, p. 11899-11904Article in journal (Refereed)
    Abstract [en]

    Electrochemistry is an old but still flourishing field of research due to the importance of the efficiency and kinetics of electrochemical reactions in industrial processes and (bio-)electrochemical devices. The heterogeneous electron transfer from an electrode to a reactant in the solution has been well studied for metal, semiconductor, metal oxide, and carbon electrodes. For those electrode materials, there is little correlation between the electronic transport within the electrode material and the electron transfer occurring at the interface between the electrode and the solution. Here, we investigate the heterogeneous electron transfer between a conducting polymer electrode and a redox couple in an electrolyte. As a benchmark system, we use poly(3,4-ethylenedioxythiophene) (PEDOT) and the Ferro/ferricyanide redox couple in an aqueous electrolyte. We discovered a strong correlation between the electronic transport within the PEDOT electrode and the rate of electron transfer to the organometallic molecules in solution. We attribute this to a percolation-based charge transport within the polymer electrode directly involved in the electron transfer. We show the impact of this finding by optimizing an electrochemical thermogalvanic cell that transforms a heat flux into electrical power. The power generated by the cell increased by four orders of magnitude on changing the morphology and conductivity of the polymer electrode. As all conducting polymers are recognized to have percolation transport, we believe that this is a general phenomenon for this family of conductors.

  • 17.
    Li, Guowei
    et al.
    Max Planck Inst Chem Phys Solids, Germany.
    Sun, Yan
    Max Planck Inst Chem Phys Solids, Germany.
    Rao, Jiancun
    Univ Maryland, MD 20742 USA.
    Wu, Jiquan
    Linköping University, Department of Physics, Chemistry and Biology, Surface Physics and Chemistry. Linköping University, Faculty of Science & Engineering.
    Kumar, Anil
    Univ Groningen, Netherlands.
    Xu, Qiu Nan
    Max Planck Inst Chem Phys Solids, Germany.
    Fu, Chenguang
    Max Planck Inst Chem Phys Solids, Germany.
    Liu, Enke
    Max Planck Inst Chem Phys Solids, Germany.
    Blake, Graeme R.
    Univ Groningen, Netherlands.
    Werner, Peter
    Max Planck Inst Microstruct Phys, Germany.
    Shao, Baiqi
    Chinese Acad Sci, Peoples R China.
    Liu, Kai
    Chinese Acad Sci, Peoples R China.
    Parkin, Stuart
    Max Planck Inst Microstruct Phys, Germany.
    Liu, Xianjie
    Linköping University, Department of Physics, Chemistry and Biology, Surface Physics and Chemistry. Linköping University, Faculty of Science & Engineering.
    Fahlman, Mats
    Linköping University, Department of Physics, Chemistry and Biology, Surface Physics and Chemistry. Linköping University, Faculty of Science & Engineering.
    Liou, Sz-Chian
    Univ Maryland, MD 20742 USA.
    Auffermann, Gudrun
    Max Planck Inst Chem Phys Solids, Germany.
    Zhang, Jian
    Tech Univ Dresden, Germany; Tech Univ Dresden, Germany.
    Felser, Claudia
    Max Planck Inst Chem Phys Solids, Germany.
    Feng, Xinliang
    Tech Univ Dresden, Germany; Tech Univ Dresden, Germany.
    Carbon-Tailored Semimetal MoP as an Efficient Hydrogen Evolution Electrocatalyst in Both Alkaline and Acid Media2018In: ADVANCED ENERGY MATERIALS, ISSN 1614-6832, Vol. 8, no 24, article id 1801258Article in journal (Refereed)
    Abstract [en]

    The electrolysis processes such as hydrogen evolution reaction (HER) require high efficient catalysts with robust surface stability. A high conductivity is also necessary to speed up the charge transport between the catalyst and the electrolyte. Recently, the observation of exceedingly high conductivity in the topological semimetal MoP, has provided a model catalyst to investigate the correlation between the electrical transport and the electrocatalytic activity for the HER. Thus, MoP is encapsulated in a Mo, P codoped carbon layer (MoP@C). This composite material exhibits outstanding HER performance, with an extremely low overpotential of 49 mV at a current density of 10 mA cm(-2) and a Tafel slope of 54 mV dec(-1) in an alkaline medium. In addition, electron transport analysis indicates that MoP exhibits high conductivity and mobility due to the existence of triple-point fermions and a complex Fermi surface. Furthermore, the presence of P-C and Mo-C bonds at the interface between the carbon layer and the MoP particles modulates the band structure of MoP@C and facilitates fast electron transfer, accumulation, and subsequent delocalization, which are in turn responsible for the excellent HER activity.

  • 18.
    Yang, Jianming
    et al.
    East China Normal Univ, Peoples R China.
    Liu, Xianjie
    Linköping University, Department of Physics, Chemistry and Biology, Surface Physics and Chemistry. Linköping University, Faculty of Science & Engineering.
    Zhang, Yuexing
    Soochow Univ, Peoples R China.
    Zheng, Xuerong
    Zhejiang Univ, Peoples R China.
    He, Xiaoxiao
    East China Normal Univ, Peoples R China.
    Wang, Han
    East China Normal Univ, Peoples R China.
    Yue, Fangyu
    East China Normal Univ, Peoples R China.
    Braun, Slawomir
    Linköping University, Department of Physics, Chemistry and Biology, Surface Physics and Chemistry. Linköping University, Faculty of Science & Engineering.
    Chen, Jinquan
    East China Normal Univ, Peoples R China.
    Xu, Jianhua
    East China Normal Univ, Peoples R China.
    Li, Yanqing
    Soochow Univ, Peoples R China.
    Jin, Yizheng
    Zhejiang Univ, Peoples R China.
    Tang, Jianxin
    Soochow Univ, Peoples R China.
    Duan, Chungang
    East China Normal Univ, Peoples R China; Shanxi Univ, Peoples R China.
    Fahlman, Mats
    Linköping University, Department of Physics, Chemistry and Biology, Surface Physics and Chemistry. Linköping University, Faculty of Science & Engineering.
    Bao, Qinye
    Linköping University, Department of Physics, Chemistry and Biology, Surface Physics and Chemistry. Linköping University, Faculty of Science & Engineering. East China Normal Univ, Peoples R China; Shanxi Univ, Peoples R China.
    Comprehensive understanding of heat-induced degradation of triple-cation mixed halide perovskite for a robust solar cell2018In: Nano Energy, ISSN 2211-2855, E-ISSN 2211-3282, Vol. 54, p. 218-226Article in journal (Refereed)
    Abstract [en]

    The triple-cation mixed halide perovskite Cs-0.05(MA(0.17)FA(0.83))(0.95)Pb(I0.83Br0.17)(3) emerges as one of the most promising candidates for photovoltaics due to superior optoelectronic properties, but the thermal stability is still a major challenge for the viability of perovskite solar cells towards commercialization. Herein, we firstly explore the thermal response of the photovoltaic performances to access device physical changes. It is shown that the efficiency loss originates from decreased charge mobility, increased trap density and generation of PbI2 charge recombination centers near the interface. In-depth analysis of evolutions in morphology, chemical composition, dynamic and electronic structure of the perovskite layer at the nanometer scales indicates that it is initial dangling bonds and vacancies on the imperfect surfaces decrease the activation energy and cause the perovskite decomposition in a layer-by-layer pathway sequentially from the film surface to bulk. Based on the results, a strategy of surface passivation to improve the thermal stability is demonstrated and discussed. This work for the first time provides insights into the physical and chemical change of such triple-cation perovskite and indicates that more effort should be invested in surface treatment for enhancing perovskite device stability.

    The full text will be freely available from 2020-10-13 14:30
  • 19.
    Petsagkourakis, Ioannis
    et al.
    University of Bordeaux, France.
    Pavlopoulou, Eleni
    Institute Polytech Bordeaux Bordeaux INP, France.
    Cloutet, Eric
    University of Bordeaux, France.
    Fang Chen, Yan
    University of Bordeaux, France.
    Liu, Xianjie
    Linköping University, Department of Physics, Chemistry and Biology, Surface Physics and Chemistry. Linköping University, Faculty of Science & Engineering.
    Fahlman, Mats
    Linköping University, Department of Physics, Chemistry and Biology, Surface Physics and Chemistry. Linköping University, Faculty of Science & Engineering.
    Berggren, Magnus
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, Faculty of Science & Engineering.
    Crispin, Xavier
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, Faculty of Science & Engineering.
    Dilhaire, Stefan
    University of Bordeaux, France.
    Fleury, Guillaume
    University of Bordeaux, France.
    Hadziioannou, Georges
    University of Bordeaux, France.
    Correlating the Seebeck coefficient of thermoelectric polymer thin films to their charge transport mechanism2018In: Organic electronics, ISSN 1566-1199, E-ISSN 1878-5530, Vol. 52, p. 335-341Article in journal (Refereed)
    Abstract [en]

    Room temperature flexible heat harvesters based on conducting polymers are ideally suited to cover the energy demands of the modern nomadic society. The optimization of their thermoelectric efficiency is usually sought by tuning the oxidation levels of the conducting polymers, even if such methodology is detrimental to the Seebeck coefficient (S) as both the Seebeck coefficient and the electrical conductivity (sigma) are antagonistically related to the carrier concentration. Here we report a concurrent increase of S and sigma and we experimentally derive the dependence of Seebeck coefficient on charge carrier mobility for the first time in organic electronics. Through specific control of the conducting polymer synthesis, we enabled the formation of a denser percolation network that facilitated the charge transport and the thermodiffusion of the charge carriers inside the conducting polymer layer, while the material shifted from a Fermi glass towards a semi-metal, as its crystallinity increased. This work sheds light upon the origin of the thermoelectric properties of conducting polymers, but also underlines the importance of enhanced charge carrier mobility for the design of efficient thermoelectric polymers.

  • 20.
    Wang, Heyong
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics. Linköping University, Faculty of Science & Engineering.
    Yu, Hongling
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics. Linköping University, Faculty of Science & Engineering.
    Xu, Weidong
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics. Linköping University, Faculty of Science & Engineering.
    Yuan, Zhongcheng
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics. Linköping University, Faculty of Science & Engineering.
    Yan, Zhibo
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics. Linköping University, Faculty of Science & Engineering. Nanjing Univ, Peoples R China.
    Wang, Chuan Fei
    Linköping University, Department of Physics, Chemistry and Biology, Surface Physics and Chemistry. Linköping University, Faculty of Science & Engineering.
    Liu, Xianjie
    Linköping University, Department of Physics, Chemistry and Biology, Surface Physics and Chemistry. Linköping University, Faculty of Science & Engineering.
    Fahlman, Mats
    Linköping University, Department of Physics, Chemistry and Biology, Surface Physics and Chemistry. Linköping University, Faculty of Science & Engineering.
    Liu, Jun-Ming
    Nanjing Univ, Peoples R China.
    Liu, Xiaoke
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics. Linköping University, Faculty of Science & Engineering. South China Univ Technol, Peoples R China; Zhejiang Univ, Peoples R China.
    Gao, Feng
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics. Linköping University, Faculty of Science & Engineering.
    Efficient perovskite light-emitting diodes based on a solution-processed tin dioxide electron transport layer2018In: Journal of Materials Chemistry C, ISSN 2050-7526, E-ISSN 2050-7534, Vol. 6, no 26, p. 6996-7002Article in journal (Refereed)
    Abstract [en]

    To achieve high-performance perovskite light-emitting diodes (PeLEDs), an appropriate functional layer beneath the perovskite emissive layer is significantly important to modulate the morphology of the perovskite film and to facilitate charge injection and transport in the device. Herein, for the first time, we report efficient n-i-p structured PeLEDs using solution-processed SnO2 as an electron transport layer. Three-dimensional perovskites, such as CH(NH2)(2)PbI3 and CH3NH3PbI3, are found to be more chemically compatible with SnO2 than with commonly used ZnO. In addition, SnO2 shows good transparency, excellent morphology and suitable energy levels. These properties make SnO2 a promising candidate in both three-and low-dimensional PeLEDs, among which a high external quantum efficiency of 7.9% has been realized. Furthermore, interfacial materials that are widely used to improve the device performances of ZnO-based PeLEDs are also applied on SnO2-based PeLEDs and their effects have been systematically studied. In contrast to ZnO, SnO2 modified by these interfacial materials shows detrimental effects due to photoluminescence quenching.

  • 21.
    Dimitriev, Oleg
    et al.
    NAS Ukraine, Ukraine.
    Fahlman, Mats
    Linköping University, Department of Physics, Chemistry and Biology, Surface Physics and Chemistry. Linköping University, Faculty of Science & Engineering.
    Braun, Slawomir
    Linköping University, Department of Physics, Chemistry and Biology, Surface Physics and Chemistry. Linköping University, Faculty of Science & Engineering.
    Energy level alignment at the interface of cadmium sulphide single crystal and phthalocyanines: The role of the crystal surface states2018In: Materials Chemistry and Physics, ISSN 0254-0584, E-ISSN 1879-3312, Vol. 205, p. 102-112Article in journal (Refereed)
    Abstract [en]

    Ultraviolet photoelectron spectroscopy was used to study energy levels of (0001) and (000 (1) over bar) surfaces of bare CdS crystal terminated with Cd and S atoms, respectively, as well as energy level alignment at hybrid interfaces of CdS crystal and donor zinc phthalocyanine (PcZn) or acceptor fluoro-substituted zinc phtalocyanine (F-PcZn) layers, respectively. The data allowed us to distinguish a slight difference between ionization potential of the Cd- and S-terminated facets of the crystal and different contribution of these surfaces to formation of the interfacial dipole at the hybrid interfaces. Ionization potential for the 5 terminated surface was slightly higher as compared to the Cd-terminated one for the same crystal, and a more, positive dipole was always created on the S-terminated surface independent of whether the donor or acceptor phthalocyanine was used. The results showed that PcZn and F-PcZn render a dual effect at the CdS surface. First, the molecules created a dipole at the interface, however, the sign of this dipole was opposite for PcZn and F-PcZn, respectively. Second, the both molecules contributed to the formation of a depletion layer near the crystal surface. The role of the surface states of the crystal in the above effects has been elucidated. Interaction of PcZn and CdS surface was associated with the pinning of the upper occupied level of the surface states to the positive charge transfer state corresponding to the oxidized HOMO level of the molecule at the interface, whereas interaction of F-PcZn and CdS surface with the pinning of the upper occupied level of the surface states to the negative charge transfer corresponding to the reduced LUMO level of the molecule at the interface, i.e., similar to what is observed for the metal organic interfaces, where an upper occupied level of semiconductor surface states in our case plays the role of Fermi level in metal. (C) 2017 Elsevier B.V. All rights reserved.

  • 22.
    Fredj, Donia
    et al.
    Univ Sfax, Tunisia.
    Pourcin, Florent
    Aix Marseille Univ, France.
    Alkarsifi, Riva
    Aix Marseille Univ, France.
    Kilinc, Volkan
    Aix Marseille Univ, France.
    Liu, Xianjie
    Linköping University, Department of Physics, Chemistry and Biology, Surface Physics and Chemistry. Linköping University, Faculty of Science & Engineering.
    Ben Dkhil, Sadok
    Aix Marseille Univ, France.
    Boudjada, Nassira Chniba
    CNRS, France.
    Fahlman, Mats
    Linköping University, Department of Physics, Chemistry and Biology, Surface Physics and Chemistry. Linköping University, Faculty of Science & Engineering.
    Videlot-Ackermann, Christine
    Aix Marseille Univ, France.
    Margeat, Olivier
    Aix Marseille Univ, France.
    Ackermann, Joerg
    Aix Marseille Univ, France.
    Boujelbene, Mohamed
    Univ Sfax, Tunisia.
    Fabrication and Characterization of Hybrid Organic-Inorganic Electron Extraction Layers for Polymer Solar Cells toward Improved Processing Robustness and Air Stability2018In: ACS Applied Materials and Interfaces, ISSN 1944-8244, E-ISSN 1944-8252, Vol. 10, no 20, p. 17309-17317Article in journal (Refereed)
    Abstract [en]

    Organic-inorganic hybrid materials composed of bismuth and diaminopyridine are studied as novel materials for electron extraction layers in polymer solar cells using regular device structures. The hybrid materials are solution processed on top of two different low band gap polymers (PTB7 or PTB7-Th) as donor materials mixed with fullerene PC70BM as the acceptor. The intercalation of the hybrid layer between the photoactive layer and the aluminum cathode leads to solar cells with a power conversion efficiency of 7.8% because of significant improvements in all photovoltaic parameters, that is, short-circuit current density, fill factor, and open-circuit voltage, similar to the reference devices using ZnO as the interfacial layer. However when using thick layers of such hybrid materials for electron extraction, only small losses in photocurrent density are observed in contrast to the reference material ZnO of pronounced losses because of optical spacer effects. Importantly, these hybrid electron extraction layers also strongly improve the device stability in air compared with solar cells processed with ZnO interlayers. Both results underline the high potential of this new class of hybrid materials as electron extraction materials toward robust processing of air stable organic solar cells.

  • 23.
    Xing, Xing
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics. Linköping University, Faculty of Science & Engineering.
    Zeng, Qi
    Linköping University, Department of Physics, Chemistry and Biology, Surface Physics and Chemistry. Linköping University, Faculty of Science & Engineering.
    Vagin, Mikhail
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, Faculty of Science & Engineering.
    Fahlman, Mats
    Linköping University, Department of Physics, Chemistry and Biology, Surface Physics and Chemistry. Linköping University, Faculty of Science & Engineering.
    Zhang, Fengling
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics. Linköping University, Faculty of Science & Engineering.
    Fast switching polymeric electrochromics with facile processed water dispersed nanoparticles2018In: Nano Energy, ISSN 2211-2855, E-ISSN 2211-3282, Vol. 47, p. 123-129Article in journal (Refereed)
    Abstract [en]

    In this work, water dispersed electrochromic polymer nanoparticles (WDENs) prepared with miniemulsion process are introduced into electrochromic polymer (ECP) electrode for the first time. The poly [2, 3-bis-(3-octyloxyphenyl) quinoxaline-5,8-diyl-alt-thiophene-2,5-diyl]) nanoparticle (NP) electrode shows much faster switching speed than the compacted electrode (e.g. 2.10 s vs. 24.15 s for coloring, 8.65 s vs. 25.95 s for bleaching @ 0.4 V; 1.30 s vs. 9.20 s coloring and 1.7 s vs. 2.90 s for bleaching @ 1.0 V). Moreover, the potentiality of WDENs for universal ECPs is demonstrated. The microelectrochemical measurement indicates much more efficient counter-ion diffusion between the electrolyte and the NP films than the compacted films, which results in much faster electrochromic switching. Besides the facile and eco-friendly processing of the WDENs, all solution and low cost fabrication of ECP NP films suggest their broad applications in commercial production of polymer electrochromic display and great potential for other polymer electrochemical electronics.

  • 24.
    Zuo, Guangzheng
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Complex Materials and Devices. Linköping University, Faculty of Science & Engineering.
    Liu, Xianjie
    Linköping University, Department of Physics, Chemistry and Biology, Surface Physics and Chemistry. Linköping University, Faculty of Science & Engineering.
    Fahlman, Mats
    Linköping University, Department of Physics, Chemistry and Biology, Surface Physics and Chemistry. Linköping University, Faculty of Science & Engineering.
    Kemerink, Martijn
    Linköping University, Department of Physics, Chemistry and Biology, Complex Materials and Devices. Linköping University, Faculty of Science & Engineering.
    High Seebeck Coefficient in Mixtures of Conjugated Polymers2018In: Advanced Functional Materials, ISSN 1616-301X, E-ISSN 1616-3028, Vol. 28, no 15, article id 1703280Article in journal (Refereed)
    Abstract [en]

    A universal method to obtain record?high electronic Seebeck coefficients is demonstrated while preserving reasonable conductivities in doped blends of organic semiconductors through rational design of the density of states (DOSs). A polymer semiconductor with a shallow highest occupied molecular orbital (HOMO) level?poly(3?hexylthiophene) (P3HT) is mixed with materials with a deeper HOMO (PTB7, TQ1) to form binary blends of the type P3HTx:B1?x (0 ≤ x ≤ 1) that is p?type doped by F4TCNQ. For B = PTB7, a Seebeck coefficient S = 1100 µV K?1 with conductivity σ = 0.3 S m?1 at x = 0.10 is achieved, while for B = TQ1, S = 2000 µV K?1 and σ = 0.03 S m?1 at x = 0.05 is found. Kinetic Monte Carlo simulations with parameters based on experiments show good agreement with the experimental results, confirming the intended mechanism. The simulations are used to derive a design rule for parameter tuning. These results can become relevant for low?power, low?cost applications like (providing power to) autonomous sensors, in which a high Seebeck coefficient translates directly to a proportionally reduced number of legs in the thermogenerator, and hence in reduced fabrication cost and complexity.

  • 25.
    Ning, Weihua
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics. Linköping University, Faculty of Science & Engineering. Nanjing Tech Univ, Peoples R China.
    Wang, Feng
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics. Linköping University, Faculty of Science & Engineering.
    Wu, Bo
    Nanyang Technol Univ, Singapore.
    Lu, Jun
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Yan, Zhibo
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics. Linköping University, Faculty of Science & Engineering. Nanjing Univ, Peoples R China.
    Liu, Xianjie
    Linköping University, Department of Physics, Chemistry and Biology, Surface Physics and Chemistry. Linköping University, Faculty of Science & Engineering.
    Tao, Youtian
    Nanjing Tech Univ, Peoples R China.
    Liu, Jun-Ming
    Nanjing Univ, Peoples R China.
    Huang, Wei
    Nanjing Tech Univ, Peoples R China.
    Fahlman, Mats
    Linköping University, Department of Physics, Chemistry and Biology, Surface Physics and Chemistry. Linköping University, Faculty of Science & Engineering.
    Hultman, Lars
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Sum, Tze Chien
    Nanyang Technol Univ, Singapore.
    Gao, Feng
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics. Linköping University, Faculty of Science & Engineering.
    Long Electron-Hole Diffusion Length in High-Quality Lead-Free Double Perovskite Films2018In: Advanced Materials, ISSN 0935-9648, E-ISSN 1521-4095, Vol. 30, no 20, article id 1706246Article in journal (Refereed)
    Abstract [en]

    Developing environmentally friendly perovskites has become important in solving the toxicity issue of lead-based perovskite solar cells. Here, the first double perovskite (Cs2AgBiBr6) solar cells using the planar structure are demonstrated. The prepared Cs2AgBiBr6 films are composed of high-crystal-quality grains with diameters equal to the film thickness, thus minimizing the grain boundary length and the carrier recombination. These high-quality double perovskite films show long electron-hole diffusion lengths greater than 100 nm, enabling the fabrication of planar structure double perovskite solar cells. The resulting solar cells based on planar TiO2 exhibit an average power conversion efficiency over 1%. This work represents an important step forward toward the realization of environmentally friendly solar cells and also has important implications for the applications of double perovskites in other optoelectronic devices.

  • 26.
    Zuo, Guangzheng
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Complex Materials and Devices. Linköping University, Faculty of Science & Engineering.
    Liu, Xianjie
    Linköping University, Department of Physics, Chemistry and Biology, Surface Physics and Chemistry. Linköping University, Faculty of Science & Engineering.
    Fahlman, Mats
    Linköping University, Department of Physics, Chemistry and Biology, Surface Physics and Chemistry. Linköping University, Faculty of Science & Engineering.
    Kemerink, Martijn
    Linköping University, Department of Physics, Chemistry and Biology, Complex Materials and Devices. Linköping University, Faculty of Science & Engineering.
    Morphology Determines Conductivity and Seebeck Coefficient in Conjugated Polymer Blends2018In: ACS Applied Materials and Interfaces, ISSN 1944-8244, E-ISSN 1944-8252, Vol. 10, no 11, p. 9638-9644Article in journal (Refereed)
    Abstract [en]

    The impact of nanoscale morphology on conductivity and Seebeck coefficient in p-type doped all-polymer blend systems is investigated. For a strongly phase separated system (P3HT:PTB7), we achieve a Seebeck coefficient that peaks at S similar to 1100 mu V/K with conductivity sigma similar to 3 x 10(-3) S/cm for 90% PTB7. In marked contrast, for well-mixed systems (P3HT:PTB7 with 5% diiodooctane (DIO), P3HT:PCPDTBT), we find an almost constant S similar to 140 mu V/K and sigma similar to 1 S/cm despite the energy levels being (virtually) identical in both cases. The results are interpreted in terms of a variable range hopping (VRH) model where a peak in S and a minimum in a arise when the percolation pathway contains both host and guest sites, in which the latter acts as energetic trap. For well-mixed blends of the investigated compositions, VRH enables percolation pathways that only involve isolated guest sites, whereas the large distance between guest clusters in phase separated blends enforces (energetically unfavorable) hops via the host. The experimentally observed trends are in good agreement with the results of atomistic kinetic Monte Carlo simulations accounting for the differences in nanoscale morphology.

  • 27.
    Guo, Xuewen
    et al.
    East China Normal Univ, Peoples R China.
    Zhang, Yuexing
    Soochow Univ, Peoples R China.
    Liu, Xianjie
    Linköping University, Department of Physics, Chemistry and Biology, Surface Physics and Chemistry. Linköping University, Faculty of Science & Engineering.
    Braun, Slawomir
    Linköping University, Department of Physics, Chemistry and Biology, Surface Physics and Chemistry. Linköping University, Faculty of Science & Engineering.
    Wang, Zhiquan
    East China Normal Univ, Peoples R China.
    Li, Bo
    East China Normal Univ, Peoples R China.
    Li, Yanqing
    Soochow Univ, Peoples R China.
    Duan, Chungang
    East China Normal Univ, Peoples R China; Shanxi Univ, Peoples R China.
    Fahlman, Mats
    Linköping University, Department of Physics, Chemistry and Biology, Surface Physics and Chemistry. Linköping University, Faculty of Science & Engineering.
    Tang, Jianxin
    East China Normal Univ, Peoples R China.
    Fang, Junfeng
    Chinese Acad Sci, Peoples R China.
    Bao, Qinye
    Linköping University, Department of Physics, Chemistry and Biology, Surface Physics and Chemistry. Linköping University, Faculty of Science & Engineering. East China Normal Univ, Peoples R China.
    Novel small-molecule zwitterionic electrolyte with ultralow work function as cathode modifier for inverted polymer solar cells2018In: Organic electronics, ISSN 1566-1199, E-ISSN 1878-5530, Vol. 59, p. 15-20Article in journal (Refereed)
    Abstract [en]

    Interfacial compatibility between the electrode and organic semiconductor plays a critical role in controlling the charge transport and hence efficiency of organic solar cell. Here, we introduce a novel small-molecule zwitterionic electrolyte (S1) combined with ZnO as electron transporting interlayer employed for the inverted PTB7:PC71BM bulk heterojunction solar cell. The resulting device with the S1/ZnO stacked interlayer achieves a high PCE of 8.59%, obtaining a 16.2% improvement over the control device performance of 7.4% without the S1 attributed to the significant increased short-circuit current density and fill factor. The interfacial properties are investigated. It is found that the S1/ZnO interlayer possess an ultralow work function of 3.6 eV, which originates from the interfacial double dipole step induced by the zwitterionic side chain electrostatic realignment at interface. The S1/ZnO interlayer exhibits the excellent charge extraction ability, suppresses the charge recombination loss and decreases the series resistance at the active layer/electrode contact.

  • 28.
    Yang, Jianming
    et al.
    East China Normal Univ, Peoples R China.
    Yuan, Zhongcheng
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics. Linköping University, Faculty of Science & Engineering.
    Liu, Xianjie
    Linköping University, Department of Physics, Chemistry and Biology, Surface Physics and Chemistry. Linköping University, Faculty of Science & Engineering.
    Braun, Slawomir
    Linköping University, Department of Physics, Chemistry and Biology, Surface Physics and Chemistry. Linköping University, Faculty of Science & Engineering.
    Li, Yanqing
    Soochow Univ, Peoples R China.
    Tang, Jianxin
    Soochow Univ, Peoples R China.
    Gao, Feng
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics. Linköping University, Faculty of Science & Engineering.
    Duan, Chungang
    East China Normal Univ, Peoples R China; Shanxi Univ, Peoples R China.
    Fahlman, Mats
    Linköping University, Department of Physics, Chemistry and Biology, Surface Physics and Chemistry. Linköping University, Faculty of Science & Engineering.
    Bao, Qinye
    Linköping University, Department of Physics, Chemistry and Biology, Surface Physics and Chemistry. Linköping University, Faculty of Science & Engineering. East China Normal Univ, Peoples R China.
    Oxygen- and Water-Induced Energetics Degradation in Organometal Halide Perovskites2018In: ACS Applied Materials and Interfaces, ISSN 1944-8244, E-ISSN 1944-8252, Vol. 10, no 18, p. 16225-16230Article in journal (Refereed)
    Abstract [en]

    Organometal halide perovskites are under rapid development, and significant focus has been placed on their stability that currently presents a major obstacle for practical application. Energetics plays a vital role in charge injection/extraction and transport properties in devices. Here, we in situ investigate oxygen and water-induced energetics degradation in organometal halide perovskite films. Oxygen gas induces an upward shift of the vacuum level of the perovskite films because of the formation of an oxygen induced surface dipole, water vapor causes a significant vacuum-level downshift, and the valence band binding energy referenced to the Fermi level simultaneously increases so as to keep the ionization potential of the perovskite films unchanged. Moreover, the chemical compositions, crystalline structures, surface morphologies, and dynamical properties also are monitored and analyzed in detail. These results are indispensable to understand the degradation mechanisms and to perform the optimizations of stable materials and devices in the future.

  • 29.
    Wang, Chuanfei
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Surface Physics and Chemistry. Linköping University, Faculty of Science & Engineering.
    Ouyang, Liangqi
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics. Linköping University, Faculty of Science & Engineering.
    Xu, Xiaofeng
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics. Linköping University, Faculty of Science & Engineering.
    Braun, Slawomir
    Linköping University, Department of Physics, Chemistry and Biology, Surface Physics and Chemistry. Linköping University, Faculty of Science & Engineering.
    Liu, Xianjie
    Linköping University, Department of Physics, Chemistry and Biology, Surface Physics and Chemistry. Linköping University, Faculty of Science & Engineering.
    Fahlman, Mats
    Linköping University, Department of Physics, Chemistry and Biology, Surface Physics and Chemistry. Linköping University, Faculty of Science & Engineering.
    Relationship of Ionization Potential and Oxidation Potential of Organic Semiconductor Films Used in Photovoltaics2018In: Solar RRL, ISSN 2367-198X, Vol. 2, no 9Article in journal (Refereed)
    Abstract [en]

    Ultraviolet photoelectron spectroscopy (UPS) and cyclic voltammetry (CV) are employed to measure energy levels for charge transport in organic semiconductor films. A series of classical molecules/polymers used in organic bulk heterojunction solar cells are deposited on platinum substrates/electrodes to form thin films and a linear relationship of vertical ionization potential (IP) measured by UPS and relative oxidation potential (Eox) obtained by CV is found, with a slope equal to unity. The intercept varies with the different reference redox couples and repeated potential sweep numbers during experiment processes. The relationship provides for an easy conversion of values obtained by the two techniques and correlates well with device parameters. The precision in the CV-derived IP values is not sufficient, however, to enable precise design of energy level alignment at heterojunction and the approach does not improve upon the current ?best practice? for obtaining donor ionization potential?acceptor electron affinity gaps at heterojunctions.

  • 30.
    Bao, Qinye
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Surface Physics and Chemistry. Linköping University, Faculty of Science & Engineering. East China Normal Univ, Peoples R China; Soochow Univ, Peoples R China.
    Liu, Xianjie
    Linköping University, Department of Physics, Chemistry and Biology, Surface Physics and Chemistry. Linköping University, Faculty of Science & Engineering.
    Braun, Slawomir
    Linköping University, Department of Physics, Chemistry and Biology, Surface Physics and Chemistry. Linköping University, Faculty of Science & Engineering.
    Yang, Jianming
    East China Normal Univ, Peoples R China.
    Li, Yanqing
    Soochow Univ, Peoples R China.
    Tang, Jianxin
    Soochow Univ, Peoples R China.
    Duan, Chungang
    East China Normal Univ, Peoples R China.
    Fahlman, Mats
    Linköping University, Department of Physics, Chemistry and Biology, Surface Physics and Chemistry. Linköping University, Faculty of Science & Engineering.
    The Effect of Oxygen Uptake on Charge Injection Barriers in Conjugated Polymer Films2018In: ACS Applied Materials and Interfaces, ISSN 1944-8244, E-ISSN 1944-8252, Vol. 10, no 7, p. 6491-6497Article in journal (Refereed)
    Abstract [en]

    The energy offset between the electrode Fermi level and organic semiconductor transport levels is a key parameter controlling the charge injection barrier and hence efficiency of organic electronic devices. Here, we systematically explore the effect of in situ oxygen exposure on energetics in n-type conjugated polymer P(NDI2OD-T2) films. The analysis reveals that an interfacial potential step is introduced for a series of P(NDI2OD-T2) electrode contacts, causing a nearly constant downshift of the vacuum level, while the ionization energies versus vacuum level remain constant. These findings are attributed to the establishment of a so-called double-dipole step via motion of charged molecules and will modify the charge injection barriers at electrode contact. We further demonstrate that the same behavior occurs when oxygen interacts with p-type polymer TQ1 films, indicating it is possible to be a universal effect for organic semiconductOrs.

  • 31.
    Munoz, William Armando
    et al.
    Linköping University, Department of Science and Technology. Linköping University, Faculty of Science & Engineering.
    Crispin, Xavier
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, Faculty of Science & Engineering.
    Fahlman, Mats
    Linköping University, Department of Physics, Chemistry and Biology, Surface Physics and Chemistry. Linköping University, Faculty of Science & Engineering.
    Zozoulenko, Igor
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, Faculty of Science & Engineering.
    Understanding the Impact of Film Disorder and Local Surface Potential in Ultraviolet Photoelectron Spectroscopy of PEDOT2018In: Macromolecular rapid communications, ISSN 1022-1336, E-ISSN 1521-3927, Vol. 39, no 4, article id 1700533Article in journal (Refereed)
    Abstract [en]

    The spectra of conducting polymers obtained using ultraviolet photoelectron spectroscopy (UPS) exhibit a typical broadening of the tail sigma(UPS) approximate to 1 eV, which by an order of magnitude exceeds a commonly accepted value of the broadening of the tail of the density of states sigma(DOS) approximate to 0.1 eV obtained using transport measurements. In this work, an origin of this anomalous broadening of the tail of the UPS spectra in a doped conducting polymer, PEDOT (poly(3,4-ethylenedioxythiophene)), is discussed. Based on the semiempirical approach and using a realistic morphological model, the density of valence states in PEDOT doped with molecular counterions is computed. It is shown that due to a disordered character of the material with randomly distributed counterions, the localized charge carriers in PEDOT crystallites experience spatially varying electrostatic potential. This leads to spatially varying local vacuum levels and binding energies. Taking this variation into account the UPS spectrum is obtained with the broadening of the tail comparable to the experimentally observed one. The results imply that the observed broadening of the tail of the UPS spectra in PEDOT provides information about a disordered spatially varying potential in the material rather than the broadening of the DOS itself.

  • 32.
    Yang, Jianming
    et al.
    East China Normal Univ, Peoples R China.
    Hong, Qiuming
    Soochow Univ, Peoples R China.
    Yuan, Zhongcheng
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics. Linköping University, Faculty of Science & Engineering.
    Xu, Ruipeng
    Soochow Univ, Peoples R China.
    Guo, Xuewen
    East China Normal Univ, Peoples R China.
    Xiong, Shaobing
    East China Normal Univ, Peoples R China.
    Liu, Xianjie
    Linköping University, Department of Physics, Chemistry and Biology, Surface Physics and Chemistry. Linköping University, Faculty of Science & Engineering.
    Braun, Slawomir
    Linköping University, Department of Physics, Chemistry and Biology, Surface Physics and Chemistry. Linköping University, Faculty of Science & Engineering.
    Li, Yanqing
    Soochow Univ, Peoples R China.
    Tang, Jianxin
    Soochow Univ, Peoples R China.
    Duan, Chungang
    East China Normal Univ, Peoples R China; Shanxi Univ, Peoples R China.
    Fahlman, Mats
    Linköping University, Department of Physics, Chemistry and Biology, Surface Physics and Chemistry. Linköping University, Faculty of Science & Engineering.
    Bao, Qinye
    Linköping University, Department of Physics, Chemistry and Biology, Surface Physics and Chemistry. Linköping University, Faculty of Science & Engineering. East China Normal Univ, Peoples R China; Shanxi Univ, Peoples R China; Soochow Univ, Peoples R China.
    Unraveling Photostability of Mixed Cation Perovskite Films in Extreme Environment2018In: Advanced Optical Materials, ISSN 2162-7568, E-ISSN 2195-1071, Vol. 6, no 20, article id 1800262Article in journal (Refereed)
    Abstract [en]

    Organometal halide perovskites exhibit a bright future for applications in solar cells, as efficiency has achieved over 22%. The long-term stability remains a major obstacle for commercialization. Here, it is found that three cationic compositional engineered perovskites, MAPb(I0.83Br0.17)(3), FA(0.83)MA(0.17)Pb(I0.83Br0.17)(3), and Cs-0.1(FA(0.83)MA(0.17))(0.9)Pb(I0.83Br0.17)(3), undergo severe degradation under white-light illumination in ultrahigh vacuum (UHV) environment, but the rate of degradation is significantly lower for the mixed cation perovskites. This is attributed to the defect-induced trap states that trigger the strong coupling between the photoexcited carriers and the crystal lattice. The observed behavior supports the view of the mixed cations suppressing the photoinduced degradation. It is further demonstrated that UHV environment remarkably accelerates the degradation of the perovskite films under illumination, which delivers a very important message that the current hybrid perovskite materials and their optoelectronic devices are not suitable for application in outer space. Moreover, the applied UHV environment can be an accelerated test method to estimate the photostability of the perovskites.

  • 33.
    Håkansson, Anna
    et al.
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, Faculty of Science & Engineering.
    Han, Shaobo
    Linköping University, Department of Science and Technology. Linköping University, Faculty of Science & Engineering.
    Wang, Suhao
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, Faculty of Science & Engineering.
    Lu, Jun
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Braun, Slawomir
    Linköping University, Department of Physics, Chemistry and Biology, Surface Physics and Chemistry. Linköping University, Faculty of Science & Engineering.
    Fahlman, Mats
    Linköping University, Department of Physics, Chemistry and Biology, Surface Physics and Chemistry. Linköping University, Faculty of Science & Engineering.
    Berggren, Magnus
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, Faculty of Science & Engineering.
    Crispin, Xavier
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, Faculty of Science & Engineering.
    Fabiano, Simone
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, Faculty of Science & Engineering.
    Effect of (3-Glycidyloxypropyl)Trimethoxysilane (GOPS) on the Electrical Properties of PEDOT:PSS Films2017In: Journal of Polymer Science Part B: Polymer Physics, ISSN 0887-6266, E-ISSN 1099-0488, Vol. 55, no 10, p. 814-820Article in journal (Refereed)
    Abstract [en]

    Poly(3,4-ethylenedioxythiophene) doped with poly(styrenesulfonate) (PEDOT:PSS) has been reported as a successful functional material in a broad variety of applications. One of the most important advantages of PEDOT:PSS is its water-solubility, which enables simple and environmental friendly manufacturing processes. Unfortunately, this also implies that pristine PEDOT:PSS films are unsuitable for applications in aqueous environments. To reach stability in polar solvents, (3-glycidyloxypropyl)trimethoxysilane (GOPS) is typically used to cross-link PEDOT:PSS. Although this strategy is widely used, its mechanism and effect on PEDOT:PSS performance have not been articulated yet. Here, we present a broad study that provides a better understanding of the effect of GOPS on the electrical and electronic properties of PEDOT:PSS. We show that the GOPS reacts with the sulfonic acid group of the excess PSS, causing a change in the PEDOT:PSS film morphology, while the oxidation level of PEDOT remains unaffected. This is at the origin of the observed conductivity changes. (c) 2017 Wiley Periodicals, Inc.

  • 34.
    Atxabal, Ainhoa
    et al.
    CIC NanoGUNE, Spain.
    Braun, Slawomir
    Linköping University, Department of Physics, Chemistry and Biology, Surface Physics and Chemistry. Linköping University, Faculty of Science & Engineering.
    Arnold, Thorsten
    Technical University of Dresden, Germany.
    Sun, Xiangnan
    National Centre Nanosci and Technology, Peoples R China.
    Parui, Subir
    CIC NanoGUNE, Spain.
    Liu, Xianjie
    Linköping University, Department of Physics, Chemistry and Biology, Surface Physics and Chemistry. Linköping University, Faculty of Science & Engineering.
    Gozalvez, Cristian
    University of Basque Country UPV EHU, Spain.
    Llopis, Roger
    CIC NanoGUNE, Spain.
    Mateo-Alonso, Aurelio
    University of Basque Country UPV EHU, Spain; Basque Fdn Science, Spain.
    Casanova, Felix
    CIC NanoGUNE, Spain; Basque Fdn Science, Spain.
    Ortmann, Frank
    Technical University of Dresden, Germany.
    Fahlman, Mats
    Linköping University, Department of Physics, Chemistry and Biology, Surface Physics and Chemistry. Linköping University, Faculty of Science & Engineering.
    Hueso, Luis E.
    CIC NanoGUNE, Spain; Basque Fdn Science, Spain.
    Energy Level Alignment at Metal/Solution-Processed Organic Semiconductor Interfaces2017In: Advanced Materials, ISSN 0935-9648, E-ISSN 1521-4095, Vol. 29, no 19, article id 1606901Article in journal (Refereed)
    Abstract [en]

    Energy barriers between the metal Fermi energy and the molecular levels of organic semiconductor devoted to charge transport play a fundamental role in the performance of organic electronic devices. Typically, techniques such as electron photoemission spectroscopy, Kelvin probe measurements, and in-device hot-electron spectroscopy have been applied to study these interfacial energy barriers. However, so far there has not been any direct method available for the determination of energy barriers at metal interfaces with n-type polymeric semiconductors. This study measures and compares metal/solution-processed electron-transporting polymer interface energy barriers by in-device hot-electron spectroscopy and ultraviolet photoemission spectroscopy. It not only demonstrates in-device hot-electron spectroscopy as a direct and reliable technique for these studies but also brings it closer to technological applications by working ex situ under ambient conditions. Moreover, this study determines that the contamination layer coming from air exposure does not play any significant role on the energy barrier alignment for charge transport. The theoretical model developed for this work confirms all the experimental observations.

  • 35.
    Bao, Qinye
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Surface Physics and Chemistry. Linköping University, Faculty of Science & Engineering. East China Normal University, Peoples R China.
    Liu, Xianjie
    Linköping University, Department of Physics, Chemistry and Biology, Surface Physics and Chemistry. Linköping University, Faculty of Science & Engineering.
    Braun, Slawomir
    Linköping University, Department of Physics, Chemistry and Biology, Surface Physics and Chemistry. Linköping University, Faculty of Science & Engineering.
    Li, Yanqing
    Soochow University, Peoples R China.
    Tang, Jianxin
    Soochow University, Peoples R China.
    Duan, Chungang
    East China Normal University, Peoples R China.
    Fahlman, Mats
    Linköping University, Department of Physics, Chemistry and Biology, Surface Physics and Chemistry. Linköping University, Faculty of Science & Engineering.
    Energy Level Alignment of N-Doping Fullerenes and Fullerene Derivatives Using Air-Stable Dopant2017In: ACS Applied Materials and Interfaces, ISSN 1944-8244, E-ISSN 1944-8252, Vol. 9, no 40, p. 35476-35482Article in journal (Refereed)
    Abstract [en]

    Doping has been proved to be one of the powerful technologies to achieve significant improvement in the performance of organic electronic devices. Herein, we systematically map out the interface properties of solution-processed air-stable n-type (4(1,3-dimethyl-2,3-dihydro-1H-benzoimidazol-2-yl)phenyl) doping fullerenes and fullerene derivatives and establish a universal energy level alignment scheme for this class of n-doped system. At low doping levels at which the charge-transfer doping induces mainly bound charges, the energy level alignment of the n-doping organic semiconductor can be described by combining integer charger transfer-induced shifts with a so-called double-dipole step. At high doping levels, significant densities of free charges are generated and the charge flows between the organic film and the conducting electrodes equilibrating the Fermi level in a classic "depletion layer" scheme. Moreover, we demonstrate that the model holds for both n- and p-doping of pi-backbone molecules and polymers. With the results, we provide wide guidance for identifying the application of the current organic n-type doping technology in organic electronics.

  • 36.
    Zhang, Qian
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Surface Physics and Chemistry. Linköping University, Faculty of Science & Engineering.
    Liu, Xianjie
    Linköping University, Department of Physics, Chemistry and Biology, Surface Physics and Chemistry. Linköping University, Faculty of Science & Engineering.
    Jiao, Fei
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, Faculty of Science & Engineering.
    Braun, Slawomir
    Linköping University, Department of Physics, Chemistry and Biology, Surface Physics and Chemistry. Linköping University, Faculty of Science & Engineering.
    Jafari, Mohammad Javad
    Linköping University, Department of Physics, Chemistry and Biology, Molecular Physics. Linköping University, Faculty of Science & Engineering.
    Crispin, Xavier
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, Faculty of Science & Engineering.
    Ederth, Thomas
    Linköping University, Department of Physics, Chemistry and Biology, Molecular Physics. Linköping University, Faculty of Science & Engineering.
    Fahlman, Mats
    Linköping University, Department of Physics, Chemistry and Biology, Surface Physics and Chemistry. Linköping University, Faculty of Science & Engineering.
    Ground-state charge transfer for NIR absorption with donor/acceptor molecules: interactions mediated via energetics and orbital symmetries2017In: Journal of Materials Chemistry C, ISSN 2050-7526, E-ISSN 2050-7534, Vol. 5, no 2, p. 275-281Article in journal (Refereed)
    Abstract [en]

    The interactions between electron donors (D) and acceptors (A) of organic semiconducting molecules are of great interest to organic electronics, e.g. electrical doping of organic semiconductors (OSCs), photo-generation of charges in organic solar cells, and light-emitting/detecting devices based on OSCs. A blend of D/A OSC is typically characterized by weak van der Waals interactions or integer charge transfer (ICT) between neighboring D/A molecules. In between these two scenarios of physical blends and ICT complexes, orbital hybridization between adjacent D/A molecules serves as a third alternative, characterized by an in situ formation of a ground state complex featuring partial charge transfer between participating donor and acceptor molecules. In this work is presented a comprehensive experimental study on partial charge-transfer complex (CPX) formed via orbital hybridization. Thiophenes and phthalocyanines are used as electron donors, while acceptor molecules of different geometries and electron affinities are employed with the aim to clarify how orbital symmetry, energy level alignment and steric hindrance affect orbital hybridization and subsequent tuning of the optical band-gap into the near infrared (NIR) region.

  • 37.
    Bao, Qinye
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Surface Physics and Chemistry. Linköping University, Faculty of Science & Engineering. Key Laboratory of Polar Materials and Devices, Ministry of Education, East China Normal University, Shanghai, P.R. China.
    Liu, Xianjie
    Linköping University, Department of Physics, Chemistry and Biology, Surface Physics and Chemistry. Linköping University, Faculty of Science & Engineering.
    Braun, Slawomir
    Linköping University, Department of Physics, Chemistry and Biology, Surface Physics and Chemistry. Linköping University, Faculty of Science & Engineering.
    Yanqing, Li
    Institute of Functional Nano & Soft Materials (FUNSOM), Soochow University, Suzhou, P.R. China.
    Jianxin, Tang
    Institute of Functional Nano & Soft Materials (FUNSOM), Soochow University, Suzhou, P.R. China.
    Chungang, Duan
    Key Laboratory of Polar Materials and Devices, Ministry of Education, East China Normal University, Shanghai, P.R. China.
    Fahlman, Mats
    Linköping University, Department of Physics, Chemistry and Biology, Surface Physics and Chemistry. Linköping University, Faculty of Science & Engineering.
    Intermixing Effect on Electronic Structures of TQ1:PC71BM Bulk Heterojunction in Organic Photovoltaics2017In: Solar RRL, ISSN 2367-198X, Vol. 1, no 10, article id 1700142Article in journal (Refereed)
    Abstract [en]

    The interface energetics and intermixing effects of the donor/acceptor bulk heterojunction (BHJ) blends of poly[2,3‐bis‐(3‐octyloxyphenyl) quinoxaline‐5, 8‐dilyl‐alt‐thiophene‐2, 5‐diyl]: [6,6]‐phenyl C71butyric acid methyl ester (TQ1:PC71BM) have been investigated using ultraviolet photoemission spectroscopy (UPS) in combination with the integer charge transfer model. The TQ1:PC71BM represents the useful model system for BHJ organic photovoltaics featuring effective charge generation and transport. It finds out that the positive integer charge state of TQ1 are equal in energy to the negative integer charge state of PC71BM, leading to a negligible potential step at TQ1:PC71BM interface and thus the vacuum level alignment. It is observed that the TQ1 accumulates on the top of TQ1:PC71BM BHJ and UPS spectra as function of various blend ratios suggest that the TQ1 mixes finely with PC71BM with the little work function modification in a wide range. In addition, no significant influence of the long‐range Coulomb interactions or the intermolecular hybridization on the occupied electronic structures is present for the well‐intermixed TQ1:PC71BM BHJs. These findings provide deep insights into the properties of BHJ blends and are beneficial for the performance optimization in organic photovoltaics.

  • 38.
    Mitraka, Evangelia
    et al.
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, Faculty of Science & Engineering.
    Jafari, Mohammad Javad
    Linköping University, Department of Physics, Chemistry and Biology, Molecular Physics. Linköping University, Faculty of Science & Engineering.
    Vagin, Mikhail
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, Faculty of Science & Engineering.
    Liu, Xianjie
    Linköping University, Department of Physics, Chemistry and Biology, Surface Physics and Chemistry. Linköping University, Faculty of Science & Engineering.
    Fahlman, Mats
    Linköping University, Department of Physics, Chemistry and Biology, Surface Physics and Chemistry. Linköping University, Faculty of Science & Engineering.
    Ederth, Thomas
    Linköping University, Department of Physics, Chemistry and Biology, Molecular Physics. Linköping University, Faculty of Science & Engineering.
    Berggren, Magnus
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, Faculty of Science & Engineering.
    Jonsson, Magnus
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, Faculty of Science & Engineering.
    Crispin, Xavier
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, Faculty of Science & Engineering.
    Oxygen-induced doping on reduced PEDOT2017In: Journal of Materials Chemistry A, ISSN 2050-7488, Vol. 5, no 9, p. 4404-4412Article in journal (Refereed)
    Abstract [en]

    The conducting polymer poly(3,4-ethylenedioxythiophene) (PEDOT) has shown promise as air electrode in renewable energy technologies like metal-air batteries and fuel cells. PEDOT is based on atomic elements of high abundance and is synthesized at low temperature from solution. The mechanism of oxygen reduction reaction (ORR) over chemically polymerized PEDOT: Cl still remains controversial with eventual role of transition metal impurities. However, regardless of the mechanistic route, we here demonstrate yet another key active role of PEDOT in the ORR mechanism. Our study demonstrates the decoupling of conductivity (intrinsic property) from electrocatalysis (as an extrinsic phenomenon) yielding the evidence of doping of the polymer by oxygen during ORR. Hence, the PEDOT electrode is electrochemically reduced (undoped) in the voltage range of ORR regime, but O-2 keeps it conducting; ensuring PEDOT to act as an electrode for the ORR. The interaction of oxygen with the polymer electrode is investigated with a battery of spectroscopic techniques.

  • 39.
    Ben Dkhil, Sadok
    et al.
    Aix Marseille University, France.
    Gaceur, Meriem
    Aix Marseille University, France.
    Karim Diallo, Abdou
    Aix Marseille University, France.
    Didane, Yahia
    Aix Marseille University, France.
    Liu, Xianjie
    Linköping University, Department of Physics, Chemistry and Biology, Surface Physics and Chemistry. Linköping University, Faculty of Science & Engineering.
    Fahlman, Mats
    Linköping University, Department of Physics, Chemistry and Biology, Surface Physics and Chemistry. Linköping University, Faculty of Science & Engineering.
    Margeat, Olivier
    Aix Marseille University, France.
    Ackermann, Jorg
    Aix Marseille University, France.
    Videlot-Ackermann, Christine
    Aix Marseille University, France.
    Reduction of Charge-Carrier Recombination at ZnO Polymer Blend Interfaces in PTB7-Based Bulk Heterojunction Solar Cells Using Regular Device Structure: Impact of ZnO Nanoparticle Size and Surfactant2017In: ACS Applied Materials and Interfaces, ISSN 1944-8244, E-ISSN 1944-8252, Vol. 9, no 20, p. 17257-17265Article in journal (Refereed)
    Abstract [en]

    Cathode interfacial layers, also called electron extraction layers (EELs), based on zinc oxide (ZnO) have been studied in polymer-blend solar cells toward optimization of the opto-electric properties. Bulk heterojunction solar cells based on poly( {4, 8-bis [(2- ethylhexyl) oxy]b enzo [1,2- b :4,5-b dithiophene-2,6-diyl}{3-fluoro-2-[(2-ethylhexyl)carbonyl]- thieno[3,4-b]thiophenediy1}) (PTB7) and [6,6]-phenyl-C71-butyric acid methyl ester (PC70BM) were realized in regular structure with all-solution-processed interlayers. A pair of commercially available surfactants, ethanolamine (EA) and ethylene glycol (EG), were used to modify the surface of ZnO nanoparticles (NPs) in alcohol-based dispersion. The influence of ZnO particle size was also studied by preparing dispersions of two NP diameters (6 versus 11 nm). Here, we show that performance improvement can be obtained in polymer solar cells via the use of solution-processed ZnO EELs based on surface-modified nanoparticles. By the optimizing of the ZnO dispersion, surfactant ratio, and the resulting morphology of EELs, PTB7/PC70BM solar cells with a power-conversion efficiency of 8.2% could be obtained using small sized EG-modified ZnO NPs that allow the clear enhancement of the performance of solution processed photovoltaic devices compared to state-of-the-art ZnO-based cathode layers.

  • 40.
    Wang, Chuan Fei
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Surface Physics and Chemistry. Linköping University, Faculty of Science & Engineering.
    Xu, Xiaofeng
    Chalmers, Sweden.
    Zhang, Wei
    Lund University, Sweden.
    Ben Dkhil, Sadok
    Aix Marseille University, France.
    Meng, Xiangyi
    Xi An Jiao Tong University, Peoples R China.
    Liu, Xianjie
    Linköping University, Department of Physics, Chemistry and Biology, Surface Physics and Chemistry. Linköping University, Faculty of Science & Engineering.
    Margeat, Olivier
    Aix Marseille University, France.
    Yartsev, Arkady
    Lund University, Sweden.
    Ma, Wei
    Xi An Jiao Tong University, Peoples R China.
    Ackermann, Jorg
    Aix Marseille University, France.
    Wang, Ergang
    Chalmers, Sweden.
    Fahlman, Mats
    Linköping University, Department of Physics, Chemistry and Biology, Surface Physics and Chemistry. Linköping University, Faculty of Science & Engineering.
    Ternary organic solar cells with enhanced open circuit voltage2017In: Nano Energy, ISSN 2211-2855, E-ISSN 2211-3282, Vol. 37, p. 24-31Article in journal (Refereed)
    Abstract [en]

    By introducing a non-fullerene small molecule acceptor as a third component to typical polymer donor: fullerene acceptor binary solar cells, we demonstrate that the short circuit current density (J(sc)), open circuit voltage (V-oc), power conversion efficiency (PCE) and thermal stability can be enhanced simultaneously. The different surface energy of each component causes most of the non-fullerene acceptor molecules to self-organize at the polymer/fullerene interface, while the appropriately selected oxidation/reduction potential of the non-fullerene acceptor enables the resulting ternary junction to work through a cascade mechanism. The cascade ternary junction enhances charge generation through complementary absorption between the non-fullerene and fullerene acceptors and aids the efficient charge extraction from fullerene domains. The bimolecular recombination in the ternary blend layer is reduced as the ternary cascade junction increases the separation of holes and electrons during charge transportation and the trap assistant recombination induced by integer charge transfer (ICT) state potentially reduced due to the smaller pinning energy of inserted non-fullerene acceptor, leading to an unprecedented increase in the open circuit voltage beyond the binary reference values.

  • 41.
    Wang, Chuanfei
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Surface Physics and Chemistry. Linköping University, Faculty of Science & Engineering.
    Zhang, Wei
    Division of Chemical Physics, Lund University, Lund, Sweden.
    Meng, Xiangyi
    State Key Laboratory for Mechanical Behavior of Materials, Xi'an Jiaotong University, Xi'an, China.
    Bergqvist, Jonas
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics. Linköping University, Faculty of Science & Engineering.
    Liu, Xianjie
    Linköping University, Department of Physics, Chemistry and Biology, Surface Physics and Chemistry. Linköping University, Faculty of Science & Engineering.
    Genene, Zewdneh
    Department of Chemistry, Addis Ababa University, Addis Ababa, Ethiopia; Department of Chemistry and Chemical Engineering, Chalmers University of Technology, Göteborg, Sweden.
    Xu, Xiaofeng
    Department of Chemistry and Chemical Engineering, Chalmers University of Technology, Göteborg, Sweden.
    Yartsev, Arkady
    Division of Chemical Physics, Lund University, Lund, Sweden.
    Inganäs, Olle
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics. Linköping University, Faculty of Science & Engineering.
    Ma, Wei
    State Key Laboratory for Mechanical Behavior of Materials, Xi'an Jiaotong University, Xi'an, China.
    Wang, Ergang
    Department of Chemistry and Chemical Engineering, Chalmers University of Technology, Göteborg, Sweden.
    Fahlman, Mats
    Linköping University, Department of Physics, Chemistry and Biology, Surface Physics and Chemistry. Linköping University, Faculty of Science & Engineering.
    Ternary Organic Solar Cells with Minimum Voltage Losses2017In: Advanced Energy Materials, ISSN 1614-6840, Vol. 7, no 21, article id 1700390Article in journal (Refereed)
    Abstract [en]

    A new strategy for designing ternary solar cells is reported in this paper. A low-bandgap polymer named PTB7-Th and a high-bandgap polymer named PBDTTS-FTAZ sharing the same bulk ionization potential and interface positive integer charge transfer energy while featuring complementary absorption spectra are selected. They are used to fabricate efficient ternary solar cells, where the hole can be transported freely between the two donor polymers and collected by the electrode as in one broadband low bandgap polymer. Furthermore, the fullerene acceptor is chosen so that the energy of the positive integer charge transfer state of the two donor polymers is equal to the energy of negative integer charge transfer state of the fullerene, enabling enhanced dissociation of all polymer donor and fullerene acceptor excitons and suppressed bimolecular and trap assistant recombination. The two donor polymers feature good miscibility and energy transfer from high-bandgap polymer of PBDTTS-FTAZ to low-bandgap polymer of PTB7-Th, which contribute to enhanced performance of the ternary solar cell.

  • 42.
    Malti, Abdellah
    et al.
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, Faculty of Science & Engineering.
    Edberg, Jesper
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, Faculty of Science & Engineering.
    Granberg, Hjalmar
    Innventia AB, Stockholm.
    Ullah Khan, Zia
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, Faculty of Science & Engineering.
    Andreasen, Jens W
    Technical University of Denmark, Roskilde.
    Liu, Xianjie
    Linköping University, Department of Physics, Chemistry and Biology, Surface Physics and Chemistry. Linköping University, Faculty of Science & Engineering.
    Zhao, Dan
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, Faculty of Science & Engineering.
    Zhang, Hao
    University of Kentucky, Lexington.
    Yao, Yulong
    University of Kentucky, Lexington.
    Brill, Joseph W
    University of Kentucky, Lexington.
    Engquist, Isak
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, Faculty of Science & Engineering.
    Fahlman, Mats
    Linköping University, Department of Physics, Chemistry and Biology, Surface Physics and Chemistry. Linköping University, Faculty of Science & Engineering.
    Wågberg, Lars
    KTH Royal Institute of Technology, Stockholm.
    Crispin, Xavier
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, Faculty of Science & Engineering.
    Berggren, Magnus
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, Faculty of Science & Engineering.
    An Organic Mixed Ion–Electron Conductor for Power Electronics2016In: Advanced Science, ISSN 2198-3844, article id 1500305Article in journal (Refereed)
    Abstract [en]

    A mixed ionic–electronic conductor based on nanofibrillated cellulose composited with poly(3,4-ethylene-dioxythio­phene):­poly(styrene-sulfonate) along with high boiling point solvents is demonstrated in bulky electrochemical devices. The high electronic and ionic conductivities of the resulting nanopaper are exploited in devices which exhibit record values for the charge storage capacitance (1F) in supercapacitors and transconductance (1S) in electrochemical transistors.

  • 43.
    Bao, Qinye
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Surface Physics and Chemistry. Linköping University, Faculty of Science & Engineering.
    Fabiano, Simone
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, Faculty of Science & Engineering.
    Andersson, Mattias
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics. Linköping University, The Institute of Technology.
    Braun, Slawomir
    Linköping University, Department of Physics, Chemistry and Biology, Surface Physics and Chemistry. Linköping University, Faculty of Science & Engineering.
    Sun, Zhengyi
    Linköping University, Department of Physics, Chemistry and Biology, Surface Physics and Chemistry. Linköping University, The Institute of Technology.
    Crispin, Xavier
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, Faculty of Science & Engineering.
    Berggren, Magnus
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, Faculty of Science & Engineering.
    Liu, Xianjie
    Linköping University, Department of Physics, Chemistry and Biology, Surface Physics and Chemistry. Linköping University, Faculty of Science & Engineering.
    Fahlman, Mats
    Linköping University, Department of Physics, Chemistry and Biology, Surface Physics and Chemistry. Linköping University, Faculty of Science & Engineering.
    Energy Level Bending in Ultrathin Polymer Layers Obtained through Langmuir-Shafer Deposition2016In: Advanced Functional Materials, ISSN 1616-301X, E-ISSN 1616-3028, Vol. 26, no 7, p. 1077-1084Article in journal (Refereed)
    Abstract [en]

    The semiconductor-electrode interface impacts the function and the performance of (opto) electronic devices. For printed organic electronics the electrode surface is not atomically clean leading to weakly interacting interfaces. As a result, solution-processed organic ultrathin films on electrodes typically form islands due to dewetting. It has therefore been utterly difficult to achieve homogenous ultrathin conjugated polymer films. This has made the investigation of the correct energetics of the conjugated polymer-electrode interface impossible. Also, this has hampered the development of devices including ultrathin conjugated polymer layers. Here, LangmuirShafer-manufactured homogenous mono-and multilayers of semiconducting polymers on metal electrodes are reported and the energy level bending using photoelectron spectroscopy is tracked. The amorphous films display an abrupt energy level bending that does not extend beyond the first monolayer. These findings provide new insights of the energetics of the polymer-electrode interface and opens up for new high-performing devices based on ultrathin semiconducting polymers.

  • 44.
    Malti, Abdellah
    et al.
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, Faculty of Science & Engineering.
    Brooke, Robert
    Linköping University, Department of Science and Technology. Linköping University, Faculty of Science & Engineering.
    Liu, Xianjie
    Linköping University, Department of Physics, Chemistry and Biology, Surface Physics and Chemistry. Linköping University, Faculty of Science & Engineering.
    Zhao, Dan
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, Faculty of Science & Engineering.
    Andersson Ersman, Peter
    Acreo Swedish ICT, Sweden.
    Fahlman, Mats
    Linköping University, Department of Physics, Chemistry and Biology, Surface Physics and Chemistry. Linköping University, Faculty of Science & Engineering.
    Jonsson, Magnus
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, Faculty of Science & Engineering.
    Berggren, Magnus
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, Faculty of Science & Engineering.
    Crispin, Xavier
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, Faculty of Science & Engineering.
    Freestanding electrochromic paper2016In: Journal of Materials Chemistry C, ISSN 2050-7526, E-ISSN 2050-7534, Vol. 4, no 41, p. 9680-9686Article in journal (Refereed)
    Abstract [en]

    Electrochromic displays based on conducting polymers exhibit higher contrasts and are cheaper, faster, more durable, and easier to synthesize as well as to process than their non-polymeric counterparts. However, current devices are typically based on thin electrochromic layers on top of a reflecting surface, which limits the thickness of the polymer layer to a few hundred nanometers. Here, we embed a light-scattering material within the electrochromic material to achieve a freestanding electrochromic paper-like electrode (50 to 500 mm). The device is based on a cellulose composite combining PEDOT:PSS as the electrochromic material and TiO2 nanoparticles as the reflecting material. Owing to the excellent refractive properties of TiO2, this nanocomposite is white in the neutral state and, when reduced, turns blue resulting in a color contrast around 30. The composite has a granular morphology and, as shown by AFM, an intermingling of TiO2 and PEDOT: PSS at the surface. Variation of the amount of TiO2 within the composite material is shown to result in a trade-off in optical and electrical properties. A proof-of-concept freestanding electrochromic device was fabricated by casting all layers successively to maximize the interlayer conformation. This freestanding device was found to be stable for over 100 cycles when ramped between 3 and -3 V.

  • 45.
    Kesters, Jurgen
    et al.
    Hasselt University, Belgium.
    Govaerts, Sanne
    Hasselt University, Belgium.
    Pirotte, Geert
    Hasselt University, Belgium.
    Drijkoningen, Jeroen
    Hasselt University, Belgium.
    Chevrier, Michele
    University of Montpellier, France; University of Mons UMONS, Belgium.
    Van den Brande, Niko
    Vrije University of Brussel, Belgium.
    Liu, Xianjie
    Linköping University, Department of Physics, Chemistry and Biology, Surface Physics and Chemistry. Linköping University, Faculty of Science & Engineering.
    Fahlman, Mats
    Linköping University, Department of Physics, Chemistry and Biology, Surface Physics and Chemistry. Linköping University, Faculty of Science & Engineering.
    Van Mele, Bruno
    Vrije University of Brussel, Belgium.
    Lutsen, Laurence
    Hasselt University, Belgium.
    Vanderzande, Dirk
    Hasselt University, Belgium.
    Manca, Jean
    Hasselt University, Belgium.
    Clement, Sebastien
    University of Montpellier, France.
    Von Hauff, Elizabeth
    Vrije University of Amsterdam, Netherlands.
    Maes, Wouter
    Hasselt University, Belgium.
    High-Permittivity Conjugated Polyelectrolyte Interlayers for High-Performance Bulk Heterojunction Organic Solar Cells2016In: ACS Applied Materials and Interfaces, ISSN 1944-8244, E-ISSN 1944-8252, Vol. 8, no 10, p. 6309-6314Article in journal (Refereed)
    Abstract [en]

    Conjugated polyelectrolyte (CPE) interfacial layers present a powerful way to boost the I-V characteristics of organic photovoltaics. Nevertheless, clear guidelines with respect to the structure of high-performance interlayers are still lacking. In this work, impedance spectroscopy is applied to probe the dielectric permittivity of a series of polythiophene-based CPEs. The presence of ionic pendant groups grants the formation of a capacitive double layer, boosting the charge extraction and device efficiency. A counteracting effect is the diminishing affinity with the underlying photoactive layer. To balance these two effects, we found copolymer structures containing nonionic side chains to be beneficial.

  • 46.
    Gaceur, Meriem
    et al.
    Aix Marseille University, France.
    Ben Dkhil, Sadok
    Aix Marseille University, France.
    Duche, David
    Aix Marseille University, France.
    Bencheikh, Fatima
    Aix Marseille University, France.
    Simon, Jean-Jacques
    Aix Marseille University, France.
    Escoubas, Ludovic
    Aix Marseille University, France.
    Mansour, Mahdi
    University of Jaume 1, Spain.
    Guerrero, Antonio
    University of Jaume 1, Spain.
    Garcia-Belmonte, Germa
    University of Jaume 1, Spain.
    Liu, Xianjie
    Linköping University, Department of Physics, Chemistry and Biology, Surface Physics and Chemistry. Linköping University, Faculty of Science & Engineering.
    Fahlman, Mats
    Linköping University, Department of Physics, Chemistry and Biology, Surface Physics and Chemistry. Linköping University, Faculty of Science & Engineering.
    Dachraoui, Walid
    Aix Marseille University, France.
    Karim Diallo, Abdou
    Aix Marseille University, France.
    Videlot-Ackermann, Christine
    Aix Marseille University, France.
    Margeat, Olivier
    Aix Marseille University, France.
    Ackermann, Joerg
    Aix Marseille University, France.
    Ligand-Free Synthesis of Aluminum-Doped Zinc Oxide Nanocrystals and their Use as Optical Spacers in Color-Tuned Highly Efficient Organic Solar Cells2016In: Advanced Functional Materials, ISSN 1616-301X, E-ISSN 1616-3028, Vol. 26, no 2, p. 243-253Article in journal (Refereed)
    Abstract [en]

    The color of polymer solar cells using an opaque electrode is given by the reflected light, which depends on the composition and thickness of each layer of the device. Metal-oxide-based optical spacers are intensively studied in polymer solar cells aiming to optimize the light absorption. However, the low conductivity of materials such as ZnO and TiO2 limits the thickness of such optical spacers to tenths of nanometers. A novel synthesis route of cluster-free Al-doped ZnO (AZO) nanocrystals (NCs) is presented for solution processing of highly conductive layers without the need of temperature annealing, including thick optical spacers on top of polymer blends. The processing of 80 nm thick optical spacers based on AZO nanocrystal solutions on top of 200 nm thick polymer blend layer is demonstrated leading to improved photocurrent density of 17% compared to solar cells using standard active layers of 90 nm in combination with thin ZnO-based optical spacers. These AZO NCs also open new opportunities for the processing of high-efficiency color tuned solar cells. For the first time, it is shown that applying solution-processed thick optical spacer with polymer blends of different thicknesses can process solar cells of similar efficiency over 7% but of different colors.

  • 47.
    Wang, Chuan Fei
    et al.
    Linköping University, Department of Physics, Chemistry and Biology. Linköping University, Faculty of Science & Engineering.
    Xu, Xiaofeng
    Chalmers, Sweden.
    Zhang, Wei
    Lund University, Sweden.
    Bergqvist, Jonas
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics. Linköping University, Faculty of Science & Engineering.
    Xia, Yuxin
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics. Linköping University, Faculty of Science & Engineering.
    Meng, Xiangyi
    Xi An Jiao Tong University, Peoples R China.
    Bini, Kim
    Chalmers, Sweden.
    Ma, Wei
    Xi An Jiao Tong University, Peoples R China.
    Yartsev, Arkady
    Lund University, Sweden.
    Vandewal, Koen
    Technical University of Dresden, Germany.
    Andersson, Mats R.
    University of South Australia, Australia.
    Inganäs, Olle
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics. Linköping University, Faculty of Science & Engineering.
    Fahlman, Mats
    Linköping University, Department of Physics, Chemistry and Biology, Surface Physics and Chemistry. Linköping University, Faculty of Science & Engineering.
    Wang, Ergang
    Chalmers, Sweden.
    Low Band Gap Polymer Solar Cells With Minimal Voltage Losses2016In: ADVANCED ENERGY MATERIALS, ISSN 1614-6832, Vol. 6, no 18, article id 1600148Article in journal (Refereed)
    Abstract [en]

    One of the factors limiting the performance of organic solar cells (OSCs) is their large energy losses (E-loss) in the conversion from photons to electrons, typically believed to be around 0.6 eV and often higher than those of inorganic solar cells. In this work, a novel low band gap polymer PIDTT-TID with a optical gap of 1.49 eV is synthesized and used as the donor combined with PC 71 BM in solar cells. These solar cells attain a good power conversion efficiency of 6.7% with a high open-circuit voltage of 1.0 V, leading to the E-loss as low as 0.49 eV. A systematic study indicates that the driving force in this donor and acceptor system is sufficient for charge generation with the low E-loss. This work pushes the minimal E-loss of OSCs down to 0.49 eV, approaching the values of some inorganic and hybrid solar cells. It indicates the potential for further enhancement of the performance of OSCs by improving their V-oc since the E-loss can be minimized.

  • 48.
    del Pozo, Freddy G.
    et al.
    Institute Ciencia Mat Barcelona ICMAB CSIC, Spain; Networking Research Centre Bioengn Biomat and Nanomed CIBER, Spain.
    Fabiano, Simone
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, Faculty of Science & Engineering.
    Pfattner, Raphael
    Institute Ciencia Mat Barcelona ICMAB CSIC, Spain; Networking Research Centre Bioengn Biomat and Nanomed CIBER, Spain.
    Georgakopoulos, Stamatis
    Institute Ciencia Mat Barcelona ICMAB CSIC, Spain; Networking Research Centre Bioengn Biomat and Nanomed CIBER, Spain.
    Galindo, Sergi
    Institute Ciencia Mat Barcelona ICMAB CSIC, Spain; Networking Research Centre Bioengn Biomat and Nanomed CIBER, Spain.
    Liu, Xianjie
    Linköping University, Department of Physics, Chemistry and Biology, Surface Physics and Chemistry. Linköping University, Faculty of Science & Engineering.
    Braun, Slawomir
    Linköping University, Department of Physics, Chemistry and Biology, Surface Physics and Chemistry. Linköping University, Faculty of Science & Engineering.
    Fahlman, Mats
    Linköping University, Department of Physics, Chemistry and Biology, Surface Physics and Chemistry. Linköping University, Faculty of Science & Engineering.
    Veciana, Jaume
    Institute Ciencia Mat Barcelona ICMAB CSIC, Spain; Networking Research Centre Bioengn Biomat and Nanomed CIBER, Spain.
    Rovira, Concepcio
    Institute Ciencia Mat Barcelona ICMAB CSIC, Spain; Networking Research Centre Bioengn Biomat and Nanomed CIBER, Spain.
    Crispin, Xavier
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, Faculty of Science & Engineering.
    Berggren, Magnus
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, Faculty of Science & Engineering.
    Mas-Torrent, Marta
    Institute Ciencia Mat Barcelona ICMAB CSIC, Spain; Networking Research Centre Bioengn Biomat and Nanomed CIBER, Spain.
    Single Crystal-Like Performance in Solution-Coated Thin-Film Organic Field-Effect Transistors2016In: Advanced Functional Materials, ISSN 1616-301X, E-ISSN 1616-3028, Vol. 26, no 14, p. 2379-2386Article in journal (Refereed)
    Abstract [en]

    In electronics, the field-effect transistor (FET) is a crucial cornerstone and successful integration of this semiconductor device into circuit applications requires stable and ideal electrical characteristics over a wide range of temperatures and environments. Solution processing, using printing or coating techniques, has been explored to manufacture organic field-effect transistors (OFET) on flexible carriers, enabling radically novel electronics applications. Ideal electrical characteristics, in organic materials, are typically only found in single crystals. Tiresome growth and manipulation of these hamper practical production of flexible OFETs circuits. To date, neither devices nor any circuits, based on solution-processed OFETs, has exhibited an ideal set of characteristics similar or better than todays FET technology based on amorphous silicon. Here, bar-assisted meniscus shearing of dibenzo-tetrathiafulvalene to coat-process self-organized crystalline organic semiconducting domains with high reproducibility is reported. Including these coatings as the channel in OFETs, electric field and temperature-independent charge carrier mobility and no bias stress effects are observed. Furthermore, record-high gain in OFET inverters and exceptional operational stability in both air and water are measured.

  • 49.
    Malti, Abdellah
    et al.
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, Faculty of Science & Engineering.
    Brooke, Robert
    University of S Australia, Australia.
    Liu, Xianjie
    Linköping University, Department of Physics, Chemistry and Biology, Surface Physics and Chemistry. Linköping University, Faculty of Science & Engineering.
    Zhao, Dan
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, Faculty of Science & Engineering.
    Andersson Ersman, Peter
    AcreoSwedish ICT, Sweden.
    Fahlman, Mats
    Linköping University, Department of Physics, Chemistry and Biology, Surface Physics and Chemistry. Linköping University, Faculty of Science & Engineering.
    Berggren, Magnus
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, Faculty of Science & Engineering.
    Crispin, Xavier
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, Faculty of Science & Engineering.
    A substrate-free electrochromic device2015Manuscript (preprint) (Other academic)
    Abstract [en]

    Electrochromic displays based on conducting polymers offer higher contrast, are cheaper, faster, more durable, and easier to synthesize as well as to process than their non-polymeric counterparts. The field of organic electrochromics has made considerable strides in the last decade with the development of new materials and methods. Here, we present a cellulose composite combining PEDOT:PSS and TiO2 that is a free-standing electrochromic material. Owing to the excellent refractive properties of TiO2, this nanocomposite is white in the neutral state and, when reduced, turns blue resulting in a color contrast exceeding 30. The composite has a granular morphology and, as shown by AFM, an intermingling of TiO2 and PEDOT:PSS at the surface. Variation of TiO2 within the material led to a trade-off in optical and electrical properties. A proof of concept free-standing electrochromic device was fabricated by casting several layers, which was found to be stable over 100 cycles.

  • 50.
    Ullah Khan, Zia
    et al.
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, Faculty of Science & Engineering.
    Bubnova, Olga
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, Faculty of Science & Engineering. Optoelectronics Group, Cavendish Laboratory, University of Cambridge, Cambridge, UK.
    Jafari, Mohammad Javad
    Linköping University, Department of Physics, Chemistry and Biology, Molecular Physics. Linköping University, Faculty of Science & Engineering.
    Brooke, Robert
    Linköping University, Faculty of Science & Engineering. Linköping University, Department of Science and Technology, Physics and Electronics. University of South Australia, Mawson Institute, Mawson Lakes 5095, Australia.
    Liu, Xianjie
    Linköping University, Department of Physics, Chemistry and Biology. Linköping University, Faculty of Science & Engineering.
    Gabrielsson, Roger
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, Faculty of Science & Engineering.
    Ederth, Thomas
    Linköping University, Department of Physics, Chemistry and Biology, Molecular Physics. Linköping University, Faculty of Science & Engineering.
    Evans, Drew R.
    University of South Australia, Mawson Institute, Australia.
    Andreasen, Jens W.
    Technical University of Denmark, Department of Energy Conversion and Storage, Roskilde, Denmark.
    Fahlman, Mats
    Linköping University, Department of Physics, Chemistry and Biology. Linköping University, Faculty of Science & Engineering.
    Crispin, Xavier
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, Faculty of Science & Engineering.
    Acido-basic control of the thermoelectric properties of poly(3,4-ethylenedioxythiophene)tosylate (PEDOT-Tos) thin films2015In: Journal of Materials Chemistry C, ISSN 2050-7526, E-ISSN 2050-7534, Vol. 3, p. 10616-10623Article in journal (Refereed)
    Abstract [en]

    PEDOT-Tos is one of the conducting polymers that displays the most promising thermoelectric properties. Until now, it has been utterly difficult to control all the synthesis parameters and the morphology governing the thermoelectric properties. To improve our understanding of this material, we study the variation in the thermoelectric properties by a simple acido-basic treatment. The emphasis of this study is to elucidate the chemical changes induced by acid (HCl) or base (NaOH) treatment in PEDOT-Tos thin films using various spectroscopic and structural techniques. We could identify changes in the nanoscale morphology due to anion exchange between tosylate and Cl- or OH-. But, we identified that changing the pH leads to a tuning of the oxidation level of the polymer, which can explain the changes in thermoelectric properties. Hence, a simple acid-base treatment allows finding the optimum for the power factor in PEDOT-Tos thin films.

1234 1 - 50 of 191
CiteExportLink to result list
Permanent link
Cite
Citation style
  • apa
  • harvard1
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • oxford
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf