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  • 151.
    Felekidis, Nikolaos
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Komplexa material och system. Linköpings universitet, Tekniska fakulteten.
    Melianas, Armantas
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Biomolekylär och Organisk Elektronik. Linköpings universitet, Tekniska fakulteten.
    Kemerink, Martijn
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Komplexa material och system. Linköpings universitet, Tekniska fakulteten.
    Nonequilibrium drift-diffusion model for organic semiconductor devices2016Ingår i: PHYSICAL REVIEW B, ISSN 2469-9950, Vol. 94, nr 3, artikel-id 035205Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Two prevailing formalisms are currently used to model charge transport in organic semiconductor devices. Drift-diffusion calculations, on the one hand, are time effective but assume local thermodynamic equilibrium, which is not always realistic. Kinetic Monte Carlo models, on the other hand, do not require this assumption but are computationally expensive. Here, we present a nonequilibrium drift-diffusion model that bridges this gap by fusing the established multiple trap and release formalism with the drift-diffusion transport equation. For a prototypical photovoltaic system the model is shown to quantitatively describe, with a single set of parameters, experiments probing (1) temperature-dependent steady-state charge transport-space-charge limited currents, and (2) time-resolved charge transport and relaxation of nonequilibrated photocreated charges. Moreover, the outputs of the developed kinetic drift-diffusion model are an order of magnitude, or more, faster to compute and in good agreement with kinetic Monte Carlo calculations.

  • 152.
    Feng, Guitao
    et al.
    Chinese Academic Science, Peoples R China; University of Chinese Academic Science, Peoples R China.
    Li, Junyu
    DSM DMSC RandD Solut, Netherlands.
    Colberts, Fallon J. M.
    Eindhoven University of Technology, Netherlands.
    Li, Mengmeng
    Eindhoven University of Technology, Netherlands; Eindhoven University of Technology, Netherlands.
    Zhang, Jianqi
    National Centre Nanosci and Technology, Peoples R China.
    Yang, Fan
    Chinese Academic Science, Peoples R China; University of Chinese Academic Science, Peoples R China.
    Jin, Yingzhi
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Biomolekylär och Organisk Elektronik. Linköpings universitet, Tekniska fakulteten.
    Zhang, Fengling
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Biomolekylär och Organisk Elektronik. Linköpings universitet, Tekniska fakulteten.
    Janssen, Rene A. J.
    Eindhoven University of Technology, Netherlands; Eindhoven University of Technology, Netherlands.
    Li, Cheng
    Chinese Academic Science, Peoples R China.
    Li, Weiwei
    Chinese Academic Science, Peoples R China.
    “Double-Cable” Conjugated Polymers with Linear Backbone toward High Quantum Efficiencies in Single-Component Polymer Solar Cells2017Ingår i: Journal of the American Chemical Society, ISSN 0002-7863, E-ISSN 1520-5126, Vol. 139, nr 51, s. 18647-18656Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    A series of "double-cable" conjugated polymers were developed for application in efficient single-component polymer solar cells, in which high quantum efficiencies could be achieved due to the optimized nanophase separation between donor and acceptor parts. The new double-cable polymers contain electron-donating poly(benzodithiophene) (BDT) as linear conjugated backbone for hole transport and pendant electron-deficient perylene bisimide (PBI) units for electron transport, connected via a dodecyl linker. Sulfur and fluorine substituents were introduced to tune the energy levels and crystallinity of the conjugated polymers. The double-cable polymers adopt a "face-on" orientation in which the conjugated BDT backbone and the pendant PBI units have a preferential pi-pi stacking direction perpendicular to the substrate, favorable for interchain charge transport normal to the plane. The linear conjugated backbone acts as a scaffold for the crystallization of the PBI groups, to provide a double-cable nanophase separation of donor and acceptor phases. The optimized nanophase separation enables efficient exciton dissociation as well as charge transport as evidenced from the high-up to 80%-internal quantum efficiency for photon-to-electron conversion. In single-component organic solar cells, the double-cable polymers provide power conversion efficiency up to 4.18%. This is one of the highest performances in single-component organic solar cells. The nanophase-separated design can likely be used to achieve high-performance single-component organic solar cells.

  • 153.
    Feng, Shizhen
    et al.
    South China University of Technology, Peoples R China.
    Liu, Chang
    South China University of Technology, Peoples R China.
    Xu, Xiaofeng
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Biomolekylär och Organisk Elektronik. Linköpings universitet, Tekniska fakulteten. Chalmers University of Technology, Sweden.
    Liu, Xuncheng
    South China University of Technology, Peoples R China.
    Zhang, Lianjie
    South China University of Technology, Peoples R China.
    Nian, Yaowen
    South China University of Technology, Peoples R China.
    Cao, Yong
    South China University of Technology, Peoples R China.
    Chen, Junwu
    South China University of Technology, Peoples R China.
    Siloxane-Terminated Side Chain Engineering of Acceptor Polymers Leading to Over 7% Power Conversion Efficiencies in All-Polymer Solar Cells2017Ingår i: ACS Macro Letters, E-ISSN 2161-1653, Vol. 6, nr 11, s. 1310-1314Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    To investigate the influence of functional pendent groups on acceptor polymers and photovoltaic properties of all-polymer solar cells (all-PSCs), two novel acceptor polymers containing siloxane-terminated side chains are synthesized and characterized. Increasing the content of siloxane-terminated side chains can reduce pi-pi stacking distance and improve crystalline behavior, yet lead to poorer solubility of the acceptor polymers. By modulating the proper loadings of siloxane-terminated side chains on the acceptor polymers, the PBDB-T:PNDI-Si25 all-PSC attains a maximal power conversion efficiency (PCE) of 7.4% with an outstanding fill factor of 0.68. The results provide, new insights for developing high-performance all-PSCs through functional group engineering on the acceptor polymers, to achieve good solubility, polymer miscibility, and blend morphology.

  • 154.
    Filippini, Daniel
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tillämpad Fysik. Linköpings universitet, Tekniska högskolan.
    Åsberg, Peter
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Biomolekylär och Organisk Elektronik. Linköpings universitet, Tekniska högskolan.
    Nilsson, Peter
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Biomolekylär och Organisk Elektronik. Linköpings universitet, Tekniska högskolan.
    Inganäs, Olle
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Biomolekylär och Organisk Elektronik. Linköpings universitet, Tekniska högskolan.
    Lundström, Ingemar
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tillämpad Fysik. Linköpings universitet, Tekniska högskolan.
    Computer screen photo-assisted spectral fingerprinting of luminescent polythiophene pH reporter2004Ingår i: IEEE Sensors. Proceedings, ISSN 1930-0395, E-ISSN 2168-9229, Vol. 3, s. 1377-1380Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The capability of the computer screen photo-assisted technique (CSPT)for the spectral fingerprinting of a photoactive polythiophene derivative (POWT) used as pH reporter is demonstrated. POWT is part of a family of industrial scalable materials, well established for organic electronics and biomedical applications, which is used here to demonstrate the capability of CSPT for tracing key spectral features. The ability of CSPTfor substance classification, corroborated by principal component analysis (PCA), successfully compares to standard spectroscopy, especially considering the involved equipments: CSPT is only a computer set and a web camera.

  • 155.
    Filippini, Daniel
    et al.
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi, Tillämpad Fysik.
    Åsberg, Peter
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi, Biomolekylär och Organisk Elektronik.
    Nilsson, Peter
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi, Biomolekylär och Organisk Elektronik.
    Inganäs, Olle
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi, Biomolekylär och Organisk Elektronik.
    Lundström, Ingemar
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi, Tillämpad Fysik.
    Computer screen photo-asssited detection of complementary DNA strands using a luminescent zwitterionic polythiophene derivative2006Ingår i: Sensors and actuators. B, Chemical, ISSN 0925-4005, E-ISSN 1873-3077, Vol. 1132006, s. 410-418Artikel i tidskrift (Refereegranskat)
  • 156. Frantz, S.E.A.
    et al.
    Mikael, L.A.
    Nilsson, Peter
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Organisk Kemi. Linköpings universitet, Tekniska högskolan.
    Inganäs, Olle
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi, Biomolekylär och Organisk Elektronik.
    Hammarström, Per
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi, Biokemi.
    Quantum efficiency and two-photon absorption cross-section of conjugated polyelectrolytes used for protein conformation measurements with applications on amyloid structures2007Ingår i: Chemical Physics, ISSN 0301-0104, E-ISSN 1873-4421, Vol. 336, nr 2-3, s. 121-126Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Amyloid diseases such as Alzheimer's and spongiform encephalopathies evolve from aggregation of proteins due to misfolding of the protein structure. Early disease handling require sophisticated but yet simple techniques to follow the complex properties of the aggregation process. Conjugated polyelectrolytes (CPEs) have shown promising capabilities acting as optical biological sensors, since they can specifically bind to polypeptides both in solution and in solid phase. The structural changes in biomolecules can be monitored by changes of the optical spectra of the CPEs, both in absorption and emission modes. Notably, the studied CPEs possess multi-photon excitation capability, making them potential for in vivo imaging using laser scanning microscopy. Aggregation of proteins depends on concentration, temperature and pH. The optical effect on the molecular probe in various environments must also be investigated if applied in these environments. Here we present the results of quantum efficiency and two-photon absorption cross-section of three CPEs: POMT, POWT and PTAA in three different pH buffer systems. The extinction coefficient and quantum efficiency were measured. POMT was found to have the highest quantum efficiency being approximately 0.10 at pH 2.0. The two-photon absorption cross-section was measured for POMT and POWT and was found to be more than 18-25 times and 7-11 times that of Fluorescein, respectively. We also show how POMT fluorescence can be used to distinguish conformational differences between amyloid fibrils formed from reduced and non-reduced insulin in spectrally resolved images recorded with a laser scanning microscope using both one- and two-photon excitation. © 2007 Elsevier B.V. All rights reserved.

  • 157.
    Fu, Huiting
    et al.
    Chinese Acad Sci, Peoples R China; Univ Chinese Acad Sci, Peoples R China.
    Wang, Yuming
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Biomolekylär och Organisk Elektronik. Linköpings universitet, Tekniska fakulteten.
    Meng, Dong
    Chinese Acad Sci, Peoples R China.
    Ma, Zetong
    Chinese Acad Sci, Peoples R China; Univ Chinese Acad Sci, Peoples R China.
    Li, Yan
    Chinese Acad Sci, Peoples R China.
    Gao, Feng
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Biomolekylär och Organisk Elektronik. Linköpings universitet, Tekniska fakulteten.
    Wang, Zhaohui
    Chinese Acad Sci, Peoples R China.
    Sun, Yanming
    Beihang Univ, Peoples R China.
    Suppression of Recombination Energy Losses by Decreasing the Energetic Offsets in Perylene Diimide-Based Nonfullerene Organic Solar Cells2018Ingår i: ACS ENERGY LETTERS, ISSN 2380-8195, Vol. 3, nr 11, s. 2729-2735Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    In this work, a range of nonfullerene organic solar cells comprising two perylene diimide (PDI)-based small molecule acceptors in combination with four representative polymer donors have been investigated and compared. In addition to significant differences in the power conversion efficiency, the energy losses of photovoltaic devices vary widely for these two PDI-based acceptors when paired with different donors. The sensitive Fourier-transform photocurrent spectroscopy (FTPS) and electroluminescence (EL) measurements have been performed to quantify their respective energetic offsets (Delta(Eoffiet)) and energy losses, with the aim of understanding the distinct energy losses in the studied organic blends. By comparing these results, we find that with decreasing Delta(Eoffset), recombination loss due to the charge-transfer state absorption A both nonradiative recombination loss and radiative are suppressed; as a result, the total energy loss is decreased. These observations offer a deep understanding of how the energetic offset affects the energy losses from the viewpoint of the Shockey-Queisser limit.

  • 158.
    Fullagar, Wilfred K.
    et al.
    Lund University, Sweden; Australian National University, Australia.
    Uhlig, Jens
    Lund University, Sweden.
    Mandal, Ujjwal
    Lund University, Sweden; University of Burdwan, India.
    Kurunthu, Dharmalingam
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Biomolekylär och Organisk Elektronik. Linköpings universitet, Tekniska fakulteten. Lund University, Sweden.
    El Nahhas, Amal
    Lund University, Sweden.
    Tatsuno, Hideyuki
    Lund University, Sweden.
    Honarfar, Alireza
    Lund University, Sweden.
    Parnefjord Gustafsson, Fredrik
    Lund University, Sweden.
    Sundstrom, Villy
    Lund University, Sweden.
    Palosaari, Mikko R. J.
    University of Jyvaskyla, Finland.
    Kinnunen, Kimmo M.
    University of Jyvaskyla, Finland.
    Maasilta, Ilari J.
    University of Jyvaskyla, Finland.
    Miaja-Avila, Luis
    NIST, CO 80305 USA.
    ONeil, Galen C.
    NIST, CO 80305 USA.
    Il Joe, Young
    NIST, CO 80305 USA.
    Swetz, Daniel S.
    NIST, CO 80305 USA.
    Ullom, Joel N.
    NIST, CO 80305 USA.
    Beating Darwin-Bragg losses in lab-based ultrafast x-ray experiments2017Ingår i: STRUCTURAL DYNAMICS, ISSN 2329-7778, Vol. 4, nr 4, artikel-id 044011Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The use of low temperature thermal detectors for avoiding Darwin-Bragg losses in lab-based ultrafast experiments has begun. An outline of the background of this new development is offered, showing the relevant history and initiative taken by this work. (C) 2017 Author(s).

  • 159.
    Gabrielsson, Roger H
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Organisk Kemi. Linköpings universitet, Tekniska högskolan.
    Milczarewic, Grzegorz
    Institute of Chemistry and Technical Electrochemistry, Poznan University of Technology, Poland.
    Nagarajuc, D. H
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Biomolekylär och Organisk Elektronik. Linköpings universitet, Tekniska högskolan.
    Konradsson, Peter
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Organisk Kemi. Linköpings universitet, Tekniska högskolan.
    Inganäs, Olle
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Biomolekylär och Organisk Elektronik. Linköpings universitet, Tekniska högskolan.
    Hydrogels of polypyrrole and self doped PEDOT for porous electrodes and supercapacitors2012Manuskript (preprint) (Övrigt vetenskapligt)
    Abstract [en]

    The aim of this work is to extend the knowledge of the mechanism of electropolymerization of pyrrole and PEDOT-S by means of in situ electrochemical quartz microbalance with dissipation studies (EQCM-D), which allow us to evaluate the chemical and physical processes during electrochemical deposition of these conductive polymer composites. Meanwhile, the relationship between the morphology of the films and the mechanism of the electropolymerization of pyrrole in presence of PEDOT-S will be discussed. The resulting material is electroactive, black and conducting. This material is a polymer composite where doped polypyrrole chains are found in an environment of doped PEDOT-S chains. They can be identified through the cyclic voltammetry studies of the composite, through element composition and through their optical signatures in electrochromism. The composite has properties suitable for a supercapacitor electrode, and capacitance of up to 650 F/g has been obtained.

  • 160.
    Gadisa, Abay
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Biomolekylär och Organisk Elektronik. Linköpings universitet, Tekniska högskolan.
    Studies of Charge Transport and Energy Level in Solar Cells Based on Polymer/Fullerene Bulk Heterojunction2006Doktorsavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [en]

    π-Conjugated polymers have attracted considerable attention since they are potential candidates for various opto-electronic devices such as solar cells, light emitting iodes, photodiodes, and transistors. Electronic de vices based on conjugated polymers can be easily processed at low temperature using inexpensive technologies. This leads to cost reduction, a key-deriving factor for choosing conjugated polymers for various types of applications. In particular, polymer based solar cells are of special interest due to the fact that they can play a major role in generating clean and cheap energy in the future.

    The investigations described in thesis are aimed mainly at understanding charge transport and the role of energy le vels in solar cells based on polymer/acceptor bulk heterojunction (BHJ) active films. Best polymer based solar cells, with efficiency 4 to 5%, rely on polymer/fullerene BHJ active films. These solar cells are in an immature state to be used for energy conversion purposes. In order to enhance their performance, it is quite important to understand the efficiency-limiting factors. Solid films of conjugated polymers compose conjugation segments that are randomly distributed in space and energy. Such distributio n gives rise to the localization of charge carriers and hence broadening of electron density of states. Consequently, electronic wave functions have quite poor overlap resulting into absence of continuous band transport. Charge transport in polymers and organic materials, in general, takes place by hopping among the localized states. This makes a bottleneck to the performance of polymer-based solar cells. In this context, the knowledge of charge transport in the solar cell materials is quite important to develop materials and device architectures that boost the efficiency of such solar cells.

    Most of the transport studies are based on polyfluorene copolymers and fullerene electron acceptor molecules. Fullerenes are blended with polymers to enhance the dissociation of excited state into free carriers and transport free electrons to the respective electrode. The interaction within the polymer-fullerene complex, therefore, plays a major role in the generation and transport of both electrons and holes. In this thesis, we present and discuss the effect of various polymer/fullerene compositions on hole percolation paths. We mainly focus on hole transport since its mobility is quite small as compared to electron mobility in the fullerenes, leading to creation of spa ce charges within the bulk of the solar cell composite. Changing a polymer band gap may necessitate an appropriate acceptor type in order to fulfill the need for sufficient driving force for dissociation of photogenerated electron-hole pairs. We have observed that different acceptor types give rise to completely different hole mobility in BHJ films. The change of hole transport as a function of acceptor type and concentration is mainly attributed to morphological changes. The effect of the acceptors in connection to hole transport is also discussed. The later is supported by studies of bipolar transport in pure electron acceptor layers. Moreover, the link between charge carrier mobility and photovoltaic parameters has also been studied and presented in this thesis.

    The efficiency of polymer/fullerene-based solar cells is also significantly limited by its open-circuit voltage (Voc), a parameter that does not obey the metal-insulator-metal principle due to its complicated characteristics. In this thesis, we address the effect of varying polymer oxidation potential on Voc of the polymer/fullerene BHJ based solar cells. Systematic investigations have been performed on solar cells that comprise several polythiophene polymers blended with a fullerene derivative electron acceptor molecule. The Voc of such solar cells was found to have a strong correlation with the oxidation potential of the polymers. The upper limit to Voc of the aforementioned solar cells is thermodynamically limited by the net internal electric filed generated by the difference in energy levels of the two materials in the blend.

    The cost of polymer-based solar cells can be reduced to a great extent through realization of all-plastic and flexible solar cells. This demands the replacement of the metallic components (electrodes) by highly conducting polymer films. While hole conductor polymers are available, low work function polymer electron conductors are rare. In this thesis, prototype solar cells that utilizes a highly conducting polymer, which has a work function of ~ 4.3 eV, as a cathode are demonstrated. Development of this material may eventually lead to fabrication of large area, flexible and cheap solar cells. The transparent nature of the polymer cathode may also facilitate fabrication of multi-layer and tandem solar cells.

    In the last chapter of this thesis, we demonstrate generation of red and near infrared polarized light by employing thermally converted thin films of polyfluorene copolymers in light emitting diodes. This study, in particular, aims at fabricating polarized infrared light emitting devices.

    Delarbeten
    1. Correlation between oxidation potential and open-circuit voltage of composite solar cells based on blends of polythiophenes/fullerene derivative
    Öppna denna publikation i ny flik eller fönster >>Correlation between oxidation potential and open-circuit voltage of composite solar cells based on blends of polythiophenes/fullerene derivative
    2004 (Engelska)Ingår i: Applied Physics Letters, ISSN 0003-6951, Vol. 84, nr 9, s. 1609-1611Artikel i tidskrift (Refereegranskat) Published
    Abstract [en]

    The photovoltaic parameters of donor/acceptor blend organic solar cells are highly influenced by several parameters, such as the strength of the acceptor species, the morphology of the film due to the solvent, and the mobility of the free charge carriers. In this work, the open-circuit voltage (Voc) of solar cells based on series of conjugated polythiophene polymers were measured and compared. In every cell, the donor polymer was blended with an electron acceptor fullerene molecule. The devices were constructed in a sandwich structure with indium tin oxide (ITO)/metallic polymer (PEDOT:PSS) acting as an anode and Al or LiF/Al acting as a cathode. Comparing the Voc of all the cells shows that this important photovoltaic parameter is systematically varying with the polymer. The variation of photovoltage is attributed to the variation of the oxidation potential of the donor conjugated polymers after due consideration of the different injection conditions in the varying polymers.

    Nationell ämneskategori
    Naturvetenskap
    Identifikatorer
    urn:nbn:se:liu:diva-14219 (URN)10.1063/1.1650878 (DOI)
    Tillgänglig från: 2007-01-15 Skapad: 2007-01-15
    2. Stoichiometry dependence of charge transport in polymer/methanofullerene and polymer/C70 derivative based solar cells
    Öppna denna publikation i ny flik eller fönster >>Stoichiometry dependence of charge transport in polymer/methanofullerene and polymer/C70 derivative based solar cells
    Visa övriga...
    2006 (Engelska)Ingår i: Organic electronics, ISSN 1566-1199, Vol. 7, nr 4, s. 195-204Artikel i tidskrift (Refereegranskat) Published
    Abstract [en]

    Charge transport in a near infrared absorbing polyfluorene copolymer (APFO-Green1) and its blends with methanofullerene [6,6]-phenyl C61-butyric acid methyl ester (PCBM), and 3′-(3,5-bis-trifluoromethylphenyl)-1′-(4-nitrophenyl)pyrazolino[70]fullerene (BTPF70) is reported. PCBM and BTPF70 are electron acceptor and transporting molecules in polymer based solar cells. The BTPF70 has emerged as a new electron acceptor molecule that provides adequate exciton dissociation when blended with the low band gap polyfluorene copolymer APFO-Green1. Electron transport in both net PCBM and BTPF70 films are subjected to positional and energetic disorder, with the degree of disorder being more pronounced in BTPF70. On the other hand, mixing PCBM with conjugated polymers usually leads to increased hole mobility. We have investigated and compared the acceptor concentration dependence of charge transport in APFO-Green1/PCBM and APFO-Green1/BTPF70 blend films. For better understanding of the charge transport in the heterojunction films, the field and temperature dependence of hole transport in pure APFO-Green1 films has also been studied. It is observed that the behavior of hole mobility in the blend layer is sensitive to the acceptor type. For APFO-Green1/PCBM hole only devices, the hole mobility attains a local maximum at 67 wt.% of PCBM, while on the contrary mixing any amount of BTPF70 with APFO-Green1 results into degradation of hole transport. Electron transport in both blends, however, increases monotonically as a function of acceptor loading.

    Nyckelord
    Solar cells; Acceptor concentration; Charge transport; Space charge limited current
    Nationell ämneskategori
    Teknik och teknologier
    Identifikatorer
    urn:nbn:se:liu:diva-14220 (URN)10.1016/j.orgel.2006.01.003 (DOI)
    Tillgänglig från: 2007-01-15 Skapad: 2007-01-15 Senast uppdaterad: 2018-10-08
    3. Improvements of fill factor in solar cells based on blends of polyfluorene copolymers as electron donors
    Öppna denna publikation i ny flik eller fönster >>Improvements of fill factor in solar cells based on blends of polyfluorene copolymers as electron donors
    Visa övriga...
    2007 (Engelska)Ingår i: Thin Solid Films, ISSN 0040-6090, E-ISSN 1879-2731, Vol. 515, nr 5, s. 3126-3131Artikel i tidskrift (Refereegranskat) Published
    Abstract [en]

    The photovoltaic characteristics of solar cells based on alternating polyfluorene copolymers, poly(2,7-(9,9-dioctyl-fluorene)-alt-5,5-(4′,7′-di-2-thienyl-2′,1′,3′-benzothiadiazole)) (APFO-3), and poly(2,7-(9,9-didodecyl-fluorene)-alt-5,5-(4′,7′-di-2-thienyl-2′,1′,3′-benzothiadiazole)) (APFO-4), blended with an electron acceptor fullerene molecule [6,6]-phenyl-C61-butyric acid methyl ester (PCBM), have been investigated and compared. The two copolymers have the same aromatic backbone structure but differ by the length of their alkyl side chain. The overall photovoltaic performance of the solar cells is comparable irrespective of the copolymer used in the active layer. However, the fill factor (FF) values of the devices are strongly affected by the copolymer type. Higher FF values were realized in solar cells with APFO-4 (with longer alkyl side chain)/PCBM bulk heterojunction active layer. On the other hand, devices with blends of APFO-3/APFO-4/PCBM were found to render fill factor values that are intermediate between the values obtained in solar cells with APFO-3/PCBM and APFO-4/PCBM active film. Upon using APFO-3/APFO-4 blends as electron donors, the cell efficiency can be enhanced by about 16% as compared to cells with either APFO-3 or APFO-4. The transport of holes in each polymer obeys the model of hopping transport in disordered media. However, the degree of energetic barrier against hopping was found to be larger in APFO-3. The tuning of the photovoltaic parameters will be discussed based on studies of hole transport in the pure polymer films, and morphology of blend layers. The effect of bipolar transport in PCBM will also be discussed.

    Nyckelord
    Solar cells, Photovoltaic characteristics, Charge transport
    Nationell ämneskategori
    Fysik
    Identifikatorer
    urn:nbn:se:liu:diva-14221 (URN)10.1016/j.tsf.2006.08.043 (DOI)
    Tillgänglig från: 2007-01-15 Skapad: 2007-01-15 Senast uppdaterad: 2017-12-13
    4. Bipolar transport and infrared light emission in C60 and C70 derivative electron acceptors
    Öppna denna publikation i ny flik eller fönster >>Bipolar transport and infrared light emission in C60 and C70 derivative electron acceptors
    Visa övriga...
    2006 (Engelska)Ingår i: Applied Physics Letters, ISSN 0003-6951Artikel i tidskrift (Refereegranskat) Submitted
    Nationell ämneskategori
    Naturvetenskap
    Identifikatorer
    urn:nbn:se:liu:diva-14222 (URN)
    Tillgänglig från: 2007-01-15 Skapad: 2007-01-15
    5. Transparent polymer cathode for organic photovoltaic devices
    Öppna denna publikation i ny flik eller fönster >>Transparent polymer cathode for organic photovoltaic devices
    Visa övriga...
    2006 (Engelska)Ingår i: Synthetic metals, ISSN 0379-6779, E-ISSN 1879-3290, Vol. 156, nr 16-17, s. 1102-1107Artikel i tidskrift (Refereegranskat) Published
    Abstract [en]

    We demonstrate a prototype solar cell with a transparent polymer cathode, and indium-tin-oxide (ITO)/poly (3, 4-ethylene dioxythiophene)-poly (styrene sulphonate) (PEDOT:PSS) anode. As an active layer, thin film of a bulk heterojunction of polyfluorene copolymer poly[2,7-(9,9-dioctyl-fluorene)-alt-5,5-(4′,7′-di-2thienyl-2′,1′3′-benzothiadiazole)] (APFO-3) and an electron acceptor molecule [6] and [6]-phenyl-C61-butyric acid methyl ester (PCBM) (1:4 wt.) was sandwiched between the two transparent polymer electrodes. The cathode is another form of PEDOT formed by vapor phase polymerised PEDOT (VPP PEDOT) of conductivity 102–103 S/cm. The cathode is supported on an elastomeric substrate, and forms a conformal contact to the APFO-3/PCBM blend. Transparent solar cells are useful for building multilayer and tandem solar cells.

    Nyckelord
    PEDOT; Vapor phase polymerization; VPP–PEDOT; Soft contact lamination; All-plastic solar cell; Ultraviolet photoelectron spectroscopy
    Nationell ämneskategori
    Naturvetenskap
    Identifikatorer
    urn:nbn:se:liu:diva-14223 (URN)10.1016/j.synthmet.2006.07.006 (DOI)
    Tillgänglig från: 2007-01-15 Skapad: 2007-01-15 Senast uppdaterad: 2017-12-13Bibliografiskt granskad
    6. Red and near infrared polarized light emission from polyfluorene copolymer based light emitting diodes
    Öppna denna publikation i ny flik eller fönster >>Red and near infrared polarized light emission from polyfluorene copolymer based light emitting diodes
    2007 (Engelska)Ingår i: Applied Physics Letters, ISSN 0003-6951, E-ISSN 1077-3118, Vol. 90, nr 11, s. 113510-Artikel i tidskrift (Refereegranskat) Published
    Abstract [en]

    The authors report polarized red, electroluminescence peak at 705  nm and near infrared, electroluminescence peak at 950  nm, light emission from light emitting diodes based on two polyfluorene copolymers. The copolymers are synthesized from a fluorene monomer combined with donor-acceptor-donor comonomers and designed to have a low band gap and form birefringent liquid crystalline phases. Emission occurs from aligned thin films of polymer layers. The emissive layers are aligned by spin coating on a layer of rubbed conducting polymer poly(3,4-ethylene dioxythiophene)-poly(styrene sulphonate) and thermally converted into glassy nematic liquid crystalline state.

    Nationell ämneskategori
    Fysik
    Identifikatorer
    urn:nbn:se:liu:diva-14224 (URN)10.1063/1.2713139 (DOI)
    Tillgänglig från: 2007-01-15 Skapad: 2007-01-15 Senast uppdaterad: 2017-12-13
  • 161.
    Gadisa, Abay
    et al.
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi, Biomolekylär och Organisk Elektronik.
    Mammo, W.
    Addis Ababa University.
    Andersson, Mattias
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi, Biomolekylär och Organisk Elektronik.
    Admassie, S.
    Addis Ababa University.
    Zhang, Fengling
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi, Biomolekylär och Organisk Elektronik.
    Andersson, M.R.
    Chalmers University of Technology.
    Inganäs, Olle
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi, Biomolekylär och Organisk Elektronik.
    A New Donor-Acceptor-Donor Polyfluorence Copolymer with Balanced Electron and Hole Mobility2007Ingår i: Advanced Functional Materials, ISSN 1616-301X, E-ISSN 1616-3028, Vol. 0000, nr 00Artikel i tidskrift (Refereegranskat)
  • 162.
    Gadisa, Abay
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Biomolekylär och Organisk Elektronik. Linköpings universitet, Tekniska högskolan.
    Perzon, Erik
    Department of Chemical and Biological Engineering, Chalmers University of Technology, Göteborg, Sweden.
    Andersson, M. R.
    Inganäs, Olle
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Biomolekylär och Organisk Elektronik. Linköpings universitet, Tekniska högskolan.
    Red and near infrared polarized light emission from polyfluorene copolymer based light emitting diodes2007Ingår i: Applied Physics Letters, ISSN 0003-6951, E-ISSN 1077-3118, Vol. 90, nr 11, s. 113510-Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The authors report polarized red, electroluminescence peak at 705  nm and near infrared, electroluminescence peak at 950  nm, light emission from light emitting diodes based on two polyfluorene copolymers. The copolymers are synthesized from a fluorene monomer combined with donor-acceptor-donor comonomers and designed to have a low band gap and form birefringent liquid crystalline phases. Emission occurs from aligned thin films of polymer layers. The emissive layers are aligned by spin coating on a layer of rubbed conducting polymer poly(3,4-ethylene dioxythiophene)-poly(styrene sulphonate) and thermally converted into glassy nematic liquid crystalline state.

  • 163.
    Gadisa, Abay
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Biomolekylär och Organisk Elektronik. Linköpings universitet, Tekniska högskolan.
    Svensson, Mattias
    Department of Organic Chemistry and Polymer Technology, Chalmers University of Technology, Göteborg, Sweden.
    Andersson, Mats R.
    Department of Organic Chemistry and Polymer Technology, Chalmers University of Technology, Göteborg, Sweden.
    Inganäs, Olle
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Biomolekylär och Organisk Elektronik. Linköpings universitet, Tekniska högskolan.
    Correlation between oxidation potential and open-circuit voltage of composite solar cells based on blends of polythiophenes/fullerene derivative2004Ingår i: Applied Physics Letters, ISSN 0003-6951, Vol. 84, nr 9, s. 1609-1611Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The photovoltaic parameters of donor/acceptor blend organic solar cells are highly influenced by several parameters, such as the strength of the acceptor species, the morphology of the film due to the solvent, and the mobility of the free charge carriers. In this work, the open-circuit voltage (Voc) of solar cells based on series of conjugated polythiophene polymers were measured and compared. In every cell, the donor polymer was blended with an electron acceptor fullerene molecule. The devices were constructed in a sandwich structure with indium tin oxide (ITO)/metallic polymer (PEDOT:PSS) acting as an anode and Al or LiF/Al acting as a cathode. Comparing the Voc of all the cells shows that this important photovoltaic parameter is systematically varying with the polymer. The variation of photovoltage is attributed to the variation of the oxidation potential of the donor conjugated polymers after due consideration of the different injection conditions in the varying polymers.

  • 164.
    Gadisa, Abay
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Biomolekylär och Organisk Elektronik. Linköpings universitet, Tekniska högskolan.
    Tvingstedt, Kristofer
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Biomolekylär och Organisk Elektronik. Linköpings universitet, Tekniska högskolan.
    Admassie, Shimelis
    Linköpings universitet, Institutionen för fysik, kemi och biologi. Linköpings universitet, Tekniska högskolan.
    Lindell, Linda
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Ytors Fysik och Kemi. Linköpings universitet, Tekniska högskolan.
    Crispin, Xavier
    Linköpings universitet, Institutionen för teknik och naturvetenskap. Linköpings universitet, Tekniska högskolan.
    Andersson, Mats R.
    Department of Organic Chemistry and Polymer Technology, Chalmers University of Technology, Göteborg, Sweden.
    Salaneck, William R.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Ytors Fysik och Kemi. Linköpings universitet, Tekniska högskolan.
    Inganäs, Olle
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Biomolekylär och Organisk Elektronik. Linköpings universitet, Tekniska högskolan.
    Transparent polymer cathode for organic photovoltaic devices2006Ingår i: Synthetic metals, ISSN 0379-6779, E-ISSN 1879-3290, Vol. 156, nr 16-17, s. 1102-1107Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    We demonstrate a prototype solar cell with a transparent polymer cathode, and indium-tin-oxide (ITO)/poly (3, 4-ethylene dioxythiophene)-poly (styrene sulphonate) (PEDOT:PSS) anode. As an active layer, thin film of a bulk heterojunction of polyfluorene copolymer poly[2,7-(9,9-dioctyl-fluorene)-alt-5,5-(4′,7′-di-2thienyl-2′,1′3′-benzothiadiazole)] (APFO-3) and an electron acceptor molecule [6] and [6]-phenyl-C61-butyric acid methyl ester (PCBM) (1:4 wt.) was sandwiched between the two transparent polymer electrodes. The cathode is another form of PEDOT formed by vapor phase polymerised PEDOT (VPP PEDOT) of conductivity 102–103 S/cm. The cathode is supported on an elastomeric substrate, and forms a conformal contact to the APFO-3/PCBM blend. Transparent solar cells are useful for building multilayer and tandem solar cells.

  • 165.
    Gadisa, Abay
    et al.
    Hasselt University.
    Tvingstedt, Kristofer
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Biomolekylär och Organisk Elektronik. Linköpings universitet, Tekniska högskolan.
    Vandewal, Koen
    Hasselt University.
    Zhang, Fengling
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Biomolekylär och Organisk Elektronik. Linköpings universitet, Tekniska högskolan.
    V Manca, Jean
    Hasselt University.
    Inganäs, Olle
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Biomolekylär och Organisk Elektronik. Linköpings universitet, Tekniska högskolan.
    Bipolar Charge Transport in Fullerene Molecules in a Bilayer and Blend of Polyfluorene Copolymer and Fullerene2010Ingår i: ADVANCED MATERIALS, ISSN 0935-9648, Vol. 22, nr 9, s. 1008-Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Efficient polymer solar cells typically contain the fullerene derivative [6,6]-phenyl-C61-butyric acid methyl ester (PCBM), which promotes dissociation of excited states and enhances charge transport. The ability of PCBM to transport holes in solar cell bulk heterojunction films is monitored via the electroluminescence emission of a bulk heterojunction blend of PCBM and a polyfluorene copolymer. In polymer/fullerene bilayer diodes, fullerene emission is also observed.

  • 166.
    Gadisa, Abay
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Biomolekylär och Organisk Elektronik. Linköpings universitet, Tekniska högskolan.
    Wang, X.
    Tvingstedt, Kristofer
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Biomolekylär och Organisk Elektronik. Linköpings universitet, Tekniska högskolan.
    Oswald, F.
    Langa, F.
    Inganäs, Olle
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Biomolekylär och Organisk Elektronik. Linköpings universitet, Tekniska högskolan.
    Bipolar transport and infrared light emission in C60 and C70 derivative electron acceptors2006Ingår i: Applied Physics Letters, ISSN 0003-6951Artikel i tidskrift (Refereegranskat)
  • 167.
    Gadisa, Abay
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Biomolekylär och Organisk Elektronik. Linköpings universitet, Tekniska högskolan.
    Wang, Xiangjun
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Biomolekylär och Organisk Elektronik. Linköpings universitet, Tekniska högskolan.
    Admassie, Shimelis
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Biomolekylär och Organisk Elektronik. Linköpings universitet, Tekniska högskolan.
    Perzon, Erik
    Department of Organic Chemistry and Polymer Technology, Chalmers University of Technology, Göteborg, Sweden.
    Oswald, Frédéric
    Facultad de Ciencias del Medio Ambiente, Universidad de Castilla-La Mancha, Toledo, Spain.
    Langa, Fernando
    Facultad de Ciencias del Medio Ambiente, Universidad de Castilla-La Mancha, Toledo, Spain.
    Andersson, Mats R.
    Department of Organic Chemistry and Polymer Technology, Chalmers University of Technology, Göteborg, Sweden.
    Inganäs, Olle
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Biomolekylär och Organisk Elektronik. Linköpings universitet, Tekniska högskolan.
    Stoichiometry dependence of charge transport in polymer/methanofullerene and polymer/C70 derivative based solar cells2006Ingår i: Organic electronics, ISSN 1566-1199, Vol. 7, nr 4, s. 195-204Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Charge transport in a near infrared absorbing polyfluorene copolymer (APFO-Green1) and its blends with methanofullerene [6,6]-phenyl C61-butyric acid methyl ester (PCBM), and 3′-(3,5-bis-trifluoromethylphenyl)-1′-(4-nitrophenyl)pyrazolino[70]fullerene (BTPF70) is reported. PCBM and BTPF70 are electron acceptor and transporting molecules in polymer based solar cells. The BTPF70 has emerged as a new electron acceptor molecule that provides adequate exciton dissociation when blended with the low band gap polyfluorene copolymer APFO-Green1. Electron transport in both net PCBM and BTPF70 films are subjected to positional and energetic disorder, with the degree of disorder being more pronounced in BTPF70. On the other hand, mixing PCBM with conjugated polymers usually leads to increased hole mobility. We have investigated and compared the acceptor concentration dependence of charge transport in APFO-Green1/PCBM and APFO-Green1/BTPF70 blend films. For better understanding of the charge transport in the heterojunction films, the field and temperature dependence of hole transport in pure APFO-Green1 films has also been studied. It is observed that the behavior of hole mobility in the blend layer is sensitive to the acceptor type. For APFO-Green1/PCBM hole only devices, the hole mobility attains a local maximum at 67 wt.% of PCBM, while on the contrary mixing any amount of BTPF70 with APFO-Green1 results into degradation of hole transport. Electron transport in both blends, however, increases monotonically as a function of acceptor loading.

  • 168.
    Gadisa, Abay
    et al.
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi, Biomolekylär och Organisk Elektronik.
    Wang, Xiangjun
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi, Biomolekylär och Organisk Elektronik.
    Perzon, Erik
    Chalmers Tekniska högskola.
    Oswald, Frederic
    Universidad de castilla-La Mancha.
    Langa, F
    Universidad de Castilla -la mancha.
    Andersson, M R
    Chalmers Tekniska Högskola.
    Inganäs, Olle
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi, Biomolekylär och Organisk Elektronik.
    Effect of acceptor type on hole transport in polymer/acceptor bulk heterojunction films2006Ingår i: European Conference on Hybrid and Organic Cells, ECHOS 06,2006, 2006Konferensbidrag (Övrigt vetenskapligt)
  • 169.
    Gadisa, Abay
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Biomolekylär och Organisk Elektronik. Linköpings universitet, Tekniska högskolan.
    Zhang, Fengling
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Biomolekylär och Organisk Elektronik. Linköpings universitet, Tekniska högskolan.
    Sharma, Deepak
    Department of Electrical Engineering, Indian Institute of Technology Kanpur, Kanpur, India.
    Svensson, Mattias
    Department of Organic Chemistry and Polymer Technology, Chalmers University of Technology, Göteborg, Sweden.
    Andersson, Mats R.
    Inganäs, Olle
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Biomolekylär och Organisk Elektronik. Linköpings universitet, Tekniska högskolan.
    Improvements of fill factor in solar cells based on blends of polyfluorene copolymers as electron donors2007Ingår i: Thin Solid Films, ISSN 0040-6090, E-ISSN 1879-2731, Vol. 515, nr 5, s. 3126-3131Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The photovoltaic characteristics of solar cells based on alternating polyfluorene copolymers, poly(2,7-(9,9-dioctyl-fluorene)-alt-5,5-(4′,7′-di-2-thienyl-2′,1′,3′-benzothiadiazole)) (APFO-3), and poly(2,7-(9,9-didodecyl-fluorene)-alt-5,5-(4′,7′-di-2-thienyl-2′,1′,3′-benzothiadiazole)) (APFO-4), blended with an electron acceptor fullerene molecule [6,6]-phenyl-C61-butyric acid methyl ester (PCBM), have been investigated and compared. The two copolymers have the same aromatic backbone structure but differ by the length of their alkyl side chain. The overall photovoltaic performance of the solar cells is comparable irrespective of the copolymer used in the active layer. However, the fill factor (FF) values of the devices are strongly affected by the copolymer type. Higher FF values were realized in solar cells with APFO-4 (with longer alkyl side chain)/PCBM bulk heterojunction active layer. On the other hand, devices with blends of APFO-3/APFO-4/PCBM were found to render fill factor values that are intermediate between the values obtained in solar cells with APFO-3/PCBM and APFO-4/PCBM active film. Upon using APFO-3/APFO-4 blends as electron donors, the cell efficiency can be enhanced by about 16% as compared to cells with either APFO-3 or APFO-4. The transport of holes in each polymer obeys the model of hopping transport in disordered media. However, the degree of energetic barrier against hopping was found to be larger in APFO-3. The tuning of the photovoltaic parameters will be discussed based on studies of hole transport in the pure polymer films, and morphology of blend layers. The effect of bipolar transport in PCBM will also be discussed.

  • 170.
    Gao, Feng
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Biomolekylär och Organisk Elektronik. Linköpings universitet, Tekniska fakulteten.
    A New Acceptor for Highly Efficient Organic Solar Cells2019Ingår i: JOULE, ISSN 2542-4351, Vol. 3, nr 4, s. 908-909Artikel i tidskrift (Övrigt vetenskapligt)
    Abstract [en]

    Research into organic solar cells has gone from pure scientific curiosity to a topic of commercial relevance in the past few years, as a result of rapid development of non-fullerene acceptors. This transition is mainly driven by the development of new materials. Recently in Joule, Zou and co-workers developed a new acceptor material and reached a record efficiency for single-junction organic solar cells.

  • 171.
    Gao, Feng
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Biomolekylär och Organisk Elektronik. Linköpings universitet, Tekniska högskolan.
    Cai, C.
    Nanjing University, Peoples R China.
    Wang, Y.
    Nanjing University, Peoples R China.
    Dong, S.
    Nanjing University, Peoples R China.
    Qiu, X. Y.
    Nanjing University, Peoples R China.
    Yuan, G. L.
    Nanjing University, Peoples R China.
    Liu, Z. G.
    Nanjing University, Peoples R China.
    Liu, J. -M.
    Nanjing University, Peoples R China.
    Preparation of la-doped BiFeO3 thin films with Fe2+ ions on Si substrates2006Ingår i: Journal of Applied Physics, ISSN 0021-8979, E-ISSN 1089-7550, Vol. 99, nr 9, s. 094105-Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    La-doped BiFeO3 thin films with Fe2+ ions have been prepared on Pt/TiO2/SiO2/Si substrates by pulsed laser deposition in order to enhance the ferroelectric and magnetic properties. The targets for the film deposition were synthesized using a rapid liquid phase sintering technique to ensure the low leakage. The dielectric properties at room temperature and above were investigated. It was observed that the La doping greatly enhances the ferroelectric polarization at room temperature by modifying the film structure from rhombohedral to monoclinic. The saturation magnetization was enhanced about two times due to the Fe2+ ions in the thin films. (C) 2006 American Institute of Physics.

  • 172.
    Gao, Feng
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Biomolekylär och Organisk Elektronik. Linköpings universitet, Tekniska högskolan.
    Chen, Xinyi
    Nanjing University, China.
    Yin, Kuibo
    Nanjing University, China.
    Dong, Shuai
    Nanjing University, China.
    Ren, Zhifeng
    Boston College, USA.
    Yuan, Fang
    Nanjing University, China.
    Yu, Tao
    Nanjing University, China.
    Zou, Zhigang
    Nanjing University, China.
    Liu, Jun-Ming
    Nanjing University, China.
    Visible-light photocatalytic properties of weak magnetic BiFeO3 nanoparticles2007Ingår i: Advanced Materials, ISSN 0935-9648, E-ISSN 1521-4095, Vol. 19, nr 19, s. 2889-2892Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Polycrystalline BiFeO3 nanoparticles (size 80-120 nm) are prepared by a simple sol-gel technique. Such nanoparticles are very efficient for photocatalytic decomposition of organic contaminants under irradiation from ultraviolet to visible frequencies. The BiFeO3 nanoparticles also demonstrate weak ferromagnetism of about 0.06 mu(B)/Fe at room temperature, in good agreement with theoretical calculations.

  • 173.
    Gao, Feng
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Biomolekylär och Organisk Elektronik. Linköpings universitet, Tekniska fakulteten.
    Himmelberger, Scott
    Stanford University, CA 94305 USA.
    Andersson, Mattias
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Biomolekylär och Organisk Elektronik. Linköpings universitet, Tekniska högskolan.
    Hanifi, David
    Stanford University, CA 94305 USA.
    Xia, Yuxin
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Biomolekylär och Organisk Elektronik. Linköpings universitet, Tekniska fakulteten.
    Zhang, Shaoqing
    Chinese Academic Science, Peoples R China.
    Wang, Jianpu
    Nanjing Technical University, Peoples R China; Nanjing Technical University, Peoples R China.
    Hou, Jianhui
    Chinese Academic Science, Peoples R China.
    Salleo, Alberto
    Stanford University, CA 94305 USA.
    Inganäs, Olle
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Biomolekylär och Organisk Elektronik. Linköpings universitet, Tekniska fakulteten.
    The Effect of Processing Additives on Energetic Disorder in Highly Efficient Organic Photovoltaics: A Case Study on PBDTTT-C-T:PC71BM2015Ingår i: Advanced Materials, ISSN 0935-9648, E-ISSN 1521-4095, Vol. 27, nr 26, s. 3868-3873Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Energetic disorder, an important parameter affecting the performance of organic photovoltaics, is significantly decreased upon the addition of processing additives in a highly efficient benzodithiophene-based copolymer blend (PBDTTT-C-T:PC71BM). Wide-angle and small-angle X-ray scattering measurements suggest that the origin of this reduced energetic disorder is due to increased aggregation and a larger average fullerene domain size together with purer phases.

  • 174.
    Gao, Feng
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Biomolekylär och Organisk Elektronik. Linköpings universitet, Tekniska högskolan.
    Inganäs, Olle
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Biomolekylär och Organisk Elektronik. Linköpings universitet, Tekniska högskolan.
    Charge generation in polymer-fullerene bulk-heterojunction solar cells2014Ingår i: Physical Chemistry, Chemical Physics - PCCP, ISSN 1463-9076, E-ISSN 1463-9084, Vol. 16, nr 38, s. 20291-20304Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Charge generation in organic solar cells is a fundamental yet heavily debated issue. This article gives a balanced review of different mechanisms proposed to explain efficient charge generation in polymer-fullerene bulk-heterojunction solar cells. We discuss the effect of charge-transfer states, excess energy, external electric field, temperature, disorder of the materials, and delocalisation of the charge carriers on charge generation. Although a general consensus has not been reached yet, recent findings, based on both steady-state and transient measurements, have significantly advanced our understanding of this process.

  • 175.
    Gao, Feng
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Biomolekylär och Organisk Elektronik. Linköpings universitet, Tekniska fakulteten.
    Koster, L. Jan Anton
    Univ Groningen, Netherlands.
    Nguyen, Thuc-Quyen
    Univ Calif Santa Barbara, CA 93106 USA.
    Stingelin, Natalie
    Georgia Tech, GA 30313 USA.
    Organic Photovoltaics2018Ingår i: ADVANCED ENERGY MATERIALS, ISSN 1614-6832, Vol. 8, nr 28, artikel-id 1802706Artikel i tidskrift (Övrigt vetenskapligt)
    Abstract [en]

    n/a

  • 176.
    Gao, Feng
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Biomolekylär och Organisk Elektronik. Linköpings universitet, Tekniska högskolan.
    Li, P. L.
    Nanjing University, China.
    Weng, Y. Y.
    Nanjing University, China.
    Dong, S.
    Nanjing University, China.
    Wang, L. F.
    Nanjing University, China.
    Lv, L. Y.
    Nanjing University, China.
    Wang, K. F.
    Nanjing University, China.
    Liu, J.-M.
    Nanjing University, China.
    Ren, Z. F.
    Nanjing University, MA 02467 USA.
    Charge order suppression and weak ferromagnetism in La1/3Sr2/3FeO3 nanoparticles2007Ingår i: Applied Physics Letters, ISSN 0003-6951, E-ISSN 1077-3118, Vol. 91, nr 7, s. 072504-Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Perovskite-type polycrystalline La1/3Sr2/3FeO3 particles with different sizes (80-2000 nm) were prepared using a simple sol-gel technique. In samples of nanoparticles with a diameter of less than 300 nm, weak ferromagnetism was observed at room temperature, which was attributed to the lattice distortion. The magnetic and specific heat measurements suggest that the charge ordering state was largely suppressed due to the lowering of the particle size, but the charge ordering temperature remained unaffected. (C) 2007 American Institute of Physics.

  • 177.
    Gao, Feng
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Biomolekylär och Organisk Elektronik. Linköpings universitet, Tekniska högskolan.
    Li, Zhe
    University of Cambridge, England.
    Wang, Jianpu
    University of Cambridge, England.
    Rao, Akshay
    University of Cambridge, England.
    Howard, Ian A.
    University of Cambridge, England.
    Abrusci, Agnese
    University of Cambridge, England.
    Massip, Sylvain
    University of Cambridge, England.
    McNeill, Christopher R.
    University of Cambridge, England.
    Greenham, Neil C.
    University of Cambridge, England.
    Trap-Induced Losses in Hybrid Photovoltaics2014Ingår i: ACS Nano, ISSN 1936-0851, E-ISSN 1936-086X, Vol. 8, nr 4, s. 3213-3221Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    We investigate the loss mechanisms in hybrid photovoltaics based on blends of poly(3-hexylthiophene) with CdSe nanocrystals of various sizes. By combining the spectroscopic and electrical measurements on working devices as well as films, we identify that high trap-mediated recombination is responsible for the loss of photogenerated charge carriers in devices with small nanocrystals. In addition, we demonstrate that the reduced open-circuit voltage for devices with small nanocrystals is also caused by the traps.

  • 178.
    Gao, Feng
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Biomolekylär och Organisk Elektronik. Linköpings universitet, Tekniska högskolan.
    Qiu, X. Y.
    Nanjing University, Peoples R China.
    Yuan, Y.
    Nanjing University, Peoples R China.
    Xu, B.
    Nanjing University, Peoples R China.
    Wen, Y. Y.
    Nanjing University, Peoples R China.
    Yuan, F.
    Nanjing University, Peoples R China.
    Lv, L. Y.
    Nanjing University, Peoples R China.
    Liu, J.-M.
    Nanjing University, Peoples R China.
    Effects of substrate temperature on Bi0.8La0.2FeO3 thin films prepared by pulsed laser deposition2007Ingår i: Thin Solid Films, ISSN 0040-6090, E-ISSN 1879-2731, Vol. 515, nr 13, s. 5366-5373Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Bi0.8La0.2FeO3 thin films on Pt/TiO2/SiO2/Si substrates at various substrate temperatures from 500 degrees C to 750 degrees C are prepared by pulsed laser deposition, and their microstructures and ferroelectric/magnetic properties are carefully investigated using various techniques. It is observed that the crystallographic orientation and Fe-ion valence state depend significantly on the substrate temperature, which consequently influences considerably on the ferroelectric and magnetic properties of the thin films. A considerable improvement of the ferroelectric and magnetic properties of the thin films can be achieved by optimizing the substrate temperature for deposition. (C) 2007 Elsevier B.V. All rights reserved.

  • 179.
    Gao, Feng
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Biomolekylär och Organisk Elektronik. Linköpings universitet, Tekniska högskolan.
    Ren, Shenqiang
    University of Kansas, USA.
    Wang, Jianpu
    University of Cambridge, England.
    The renaissance of hybrid solar cells: progresses, challenges, and perspectives2013Ingår i: Energy & Environmental Science, ISSN 1754-5692, E-ISSN 1754-5706, Vol. 6, nr 7, s. 2020-2040Artikel, forskningsöversikt (Refereegranskat)
    Abstract [en]

    Solution-processed hybrid solar cells, a blend of conjugated polymers and semiconducting nanocrystals, are a promising candidate for next-generation energy-conversion devices. The renaissance of this field in recent years has yielded a much deeper understanding of optoelectronic interactions in organic–inorganic hybrid systems. In this article, we review the state-of-the-art progress in hybrid bulk heterojunction solar cells, covering new materials design, interfacial interaction, and processing control. Furthermore, critical challenges that determine photovoltaic performance and prospects for future directions are discussed.

  • 180.
    Gao, Feng
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Biomolekylär och Organisk Elektronik. Linköpings universitet, Tekniska högskolan. University of Cambridge, England.
    Tress, Wolfgang
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Biomolekylär och Organisk Elektronik. Linköpings universitet, Tekniska högskolan.
    Wang, Jianpu
    University of Cambridge, England; Nanjing Technical University, Peoples R China; Nanjing Technical University, Peoples R China.
    Inganäs, Olle
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Biomolekylär och Organisk Elektronik. Linköpings universitet, Tekniska högskolan.
    Temperature Dependence of Charge Carrier Generation in Organic Photovoltaics2015Ingår i: Physical Review Letters, ISSN 0031-9007, E-ISSN 1079-7114, Vol. 114, nr 12, s. 128701-Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The charge generation mechanism in organic photovoltaics is a fundamental yet heavily debated issue. All the generated charges recombine at the open-circuit voltage (VOC), so that investigation of recombined charges at VOC provides a unique approach to understanding charge generation. At low temperatures, we observe a decrease of VOC, which is attributed to reduced charge separation. Comparison between benchmark polymer: fullerene and polymer: polymer blends highlights the critical role of charge delocalization in charge separation and emphasizes the importance of entropy in charge generation.

  • 181.
    Gao, Feng
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Biomolekylär och Organisk Elektronik. Linköpings universitet, Tekniska högskolan.
    Yuan, Y.
    Nanjing University, 210093 China.
    Wang, K. F.
    Nanjing University, 210093 China.
    Chen, X. Y.
    Nanjing University, 210093 China.
    Chen, F.
    Nanjing University, 210093 China.
    Liu, J. -M.
    Nanjing University, 210093 China.
    Preparation and photoabsorption characterization of BiFeO3 nanowires2006Ingår i: Applied Physics Letters, ISSN 0003-6951, E-ISSN 1077-3118, Vol. 89, nr 10, s. 102506-Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Perovskite-type polycrystalline BiFeO3 (BFO) nanowires (similar to 50 nm in diameter and similar to 5 mu m in length) were synthesized using the anodized alumina template technique. An energy band gap of similar to 2.5 eV was determined from the UV-visible diffuse reflectance spectrum, and its photocatalytic ability to produce O-2 was revealed under UV irradiation. Weak ferromagnetism at room temperature and superparamagnetism at low temperature were observed for the BFO nanowires, different from the antiferromagnetic order in bulk BFO, reflecting the significant size effects on the magnetic ordering of BFO. (c) 2006 American Institute of Physics.

  • 182.
    Gedefaw, Desta A.
    et al.
    Chalmers, Sweden.
    Ma, Zaifei
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Biomolekylär och Organisk Elektronik. Linköpings universitet, Tekniska högskolan.
    Henriksson, Patrik
    Chalmers, Sweden.
    Zhang, Fengling
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Biomolekylär och Organisk Elektronik. Linköpings universitet, Tekniska högskolan.
    Andersson, Mats R.
    Chalmers, Sweden.
    Mammo, Wendimagegn
    University of Addis Ababa, Ethiopia.
    RANDOM POLYFLUORENE CO-POLYMERS DESIGNED FOR A BETTER OPTICAL ABSORPTION COVERAGE OF THE VISIBLE REGION OF THE ELECTROMAGNETIC SPECTRUM2014Ingår i: Bulletin of the Chemical Society of Ethiopia, ISSN 1011-3924, E-ISSN 1726-801X, Vol. 28, nr 1, s. 121-130Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Two alternating polyfluorenes (APFO15-F8BT and APFO3-F8BT) with full absorption of the visible region of the electromagnetic radiation were designed and synthesized for bulk-heterojunction solar cell devices. The optical and electrochemical properties of the two polymers were studied. The two polymers exhibited strong absorption in the visible region with no significant valley over the visible region extending up to 650 nm. Deep HOMO and ideally situated LUMO energy levels were the characteristics of the two polymers as revealed from the square wave voltammogram study: desired properties for extracting high open circuit voltage and for a facile charge transfer to the acceptor component in devices to take place, respectively. Photovoltaic devices were fabricated by blending the two polymers with PCBM[70] and up to similar to 2% power conversion efficiency were obtained.

  • 183.
    Gedefaw, Desta A
    et al.
    Chalmers, Sweden .
    Zhou, Yi
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Biomolekylär och Organisk Elektronik. Linköpings universitet, Tekniska fakulteten.
    Ma, Zaifei
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Biomolekylär och Organisk Elektronik. Linköpings universitet, Tekniska högskolan.
    Genene, Zewdneh
    University of Addis Ababa, Ethiopia .
    Hellstrom, Stefan
    Chalmers, Sweden .
    Zhang, Fengling
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Biomolekylär och Organisk Elektronik. Linköpings universitet, Tekniska högskolan.
    Mammo, Wendimagegn
    University of Addis Ababa, Ethiopia .
    Inganäs, Olle
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Biomolekylär och Organisk Elektronik. Linköpings universitet, Tekniska högskolan.
    Andersson, Mats R
    Chalmers, Sweden .
    Conjugated polymers with polar side chains in bulk heterojunction solar cell devices2014Ingår i: Polymer international, ISSN 0959-8103, E-ISSN 1097-0126, Vol. 63, nr 1, s. 22-30Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Two polymers with polar side chains, namely poly[2,7-(9,9-dioctylfluorene)-alt-5,5-(5,8-di-2-thienyl-(2,3-bis(3-(2-(2-methoxyethoxy)ethoxy)phenyl)quinoxaline))] (P1) and poly[2,7-(9,9-bis(2-(2-methoxyethoxy)ethyl)fluorene)-alt-5,5-(5,8-di-2-thienyl-(2,3-bis(3-(2-(2-methoxyethoxy)-ethoxy)phenyl)quinoxaline))] (P2), were synthesized for solar cell application. A series of bulk heterojunction solar cells were systematically fabricated and characterized by varying the electron-acceptor materials, processing solvents and thickness of the active layer. The results show that P1, with a higher molecular weight and good film-forming properties, performed better. The best device showed an open circuit voltage of 0.87 V, a short circuit current of 6.81 mA cm(-2) and a power conversion efficiency of 2.74% with 1:4 polymer:[6,6]-phenyl-C71-butyric acid methyl ester (PCBM[70]) mixture using o-dichlorobenzene (o-DCB) as processing solvent. P2 on the other hand showed a poorer performance with chlorobenzene as processing solvent, but a much improved performance was obtained using o-DCB instead. Thus, an open circuit voltage of 0.80 V, short circuit current of 6.21 mA cm(-2) and an overall power conversion efficiency of 2.22% were recorded for a polymer:PCBM[70] mixing ratio of 1:4. This is presumably due to the improvement of the morphology of the active layer using o-DCB as processing solvent.

  • 184.
    Gedefaw, Desta
    et al.
    Univ South Pacific, Fiji; Flinders Univ S Australia, Australia.
    Hedstrom, Svante
    Stockholm Univ, Sweden; Lund Univ, Sweden.
    Xia, Yuxin
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Biomolekylär och Organisk Elektronik. Linköpings universitet, Tekniska fakulteten.
    Persson, Petter
    Lund Univ, Sweden.
    Andersson, Mats R.
    Flinders Univ S Australia, Australia.
    Design, Synthesis and Computational Study of Fluorinated Quinoxaline-Oligothiophene-based Conjugated Polymers with Broad Spectral Coverage2018Ingår i: ChemPhysChem, ISSN 1439-4235, E-ISSN 1439-7641, Vol. 19, nr 24, s. 3393-3400Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Donor-acceptor (D-A) copolymers typically show two absorption peaks in the visible region, flanking a valley region of limited absorptivity. One strategy for more panchromatic light harvesting is to incorporate side-groups orthogonal to the polymer backbone, which enable 2D pi conjugation and can give rise to additional absorption peaks. Here we design and synthesize two D-A polymers which both carry a fluorinated quinoxaline acceptor unit, but while P1 includes a benzodithiophene donor moiety with thiophene side-groups (2D-BDT), the P2 polymer lacks 2D conjugation in its simpler pentathiophene donor segment. The P1 polymer consequently shows an atypical absorption profile with more panchromatic absorption with no apparent valley in the spectrum. In order to understand the structure-electronic relations, the optical and electrochemical properties were predicted using a previously developed computational approach. The predicted optical properties show very good agreement with the experimental results. Solar cells made from P1 show a short-circuit current more than twice as large as P2, attributed to its enhanced spectral coverage. However, poor fill factors limit the preliminary power conversion efficiencies to 3.3 % for P1 and 1.0 % for P2 as blended with PCBM[70] in a 1 : 1.5 (w/w) ratio.

  • 185.
    Gedefaw, Desta
    et al.
    Chalmers, Sweden; University of S Australia, Australia.
    Zaifei, Zaifei
    Linköpings universitet, Institutionen för fysik, kemi och biologi. Linköpings universitet, Tekniska fakulteten.
    Mulugeta, Endale
    University of Addis Ababa, Ethiopia.
    Zhao, Yang
    Linköpings universitet, Institutionen för fysik, kemi och biologi. Linköpings universitet, Tekniska fakulteten.
    Zhang, Fengling
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Biomolekylär och Organisk Elektronik. Linköpings universitet, Tekniska fakulteten.
    Andersson, Mats R.
    Chalmers, Sweden; University of S Australia, Australia.
    Mammo, Wendimagegn
    University of Addis Ababa, Ethiopia.
    An alternating copolymer of fluorene donor and quinoxaline acceptor versus a terpolymer consisting of fluorene, quinoxaline and benzothiadiazole building units: synthesis and characterization2016Ingår i: Polymer Bulletin, ISSN 0170-0839, E-ISSN 1436-2449, Vol. 73, nr 4, s. 1167-1183Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    An alternating polyfluorene copolymer based on fluorene donor and quinoxaline acceptor (P1) and an alternating terpolymer (P2) with fluorene (50 %) donor and quinoxaline (25 %) and benzothiadiazole (25 %) acceptor units were designed and synthesized for use as photoactive materials in solar cells. The presence of benzothiadiazole unit in P2 increased the optical absorption coverage in the range of 350-600 nm, which is an interesting property and a big potential for achieving improved photovoltaic performances with judicious optimization of the devices. Solar cells were fabricated from 1:4 blends of polymers-PCBM[70] using o-dichlorobenzene (o-DCB) as processing solvent, and P1 showed a power conversion efficiency (PCE) of 3.18 %, with a short-circuit current density (J (SC)) of 7.78 mA/cm(2), an open-circuit voltage (V (OC)) of 0.82 V, and a fill factor (FF) of 50 % while P2 showed an overall PCE of 2.14 % with corresponding J (SC) of 5.97 mA/cm(2), V (OC) of 0.84 V and FF of 42 %. In general, P2 gave lower J (SC) and FF presumably due to the fine domain sizes of the polymer-PCBM[70] blend as seen from the atomic force microscopy (AFM) image which might have affected the charge carrier transport. Alternating (P1) and ternary (P2) conjugated polymers were designed, synthesized and used for fabrication of photovoltaic devices. [GRAPHICS] .

  • 186.
    Gedefaw, Desta
    et al.
    Gothenburg University.
    Zhou, Yi
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Sensorvetenskap och Molekylfysik. Linköpings universitet, Tekniska högskolan.
    Hellstrom, Stefan
    Chalmers Institute of Technology.
    Lindgren, Lars
    Chalmers Institute of Technology.
    Andersson, L.Mattias
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Biomolekylär och Organisk Elektronik. Linköpings universitet, Tekniska högskolan.
    Zhang, Fengling
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Biomolekylär och Organisk Elektronik. Linköpings universitet, Tekniska högskolan.
    Mammo, Wendimagegn
    Chalmers Institute of Technology.
    Inganäs, Olle
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Biomolekylär och Organisk Elektronik. Linköpings universitet, Tekniska högskolan.
    Andersson, Mats R
    Chalmers Institute of Technology.
    Alternating copolymers of fluorene and donor-acceptor-donor segments designed for miscibility in bulk heterojunction photovoltaics2009Ingår i: JOURNAL OF MATERIALS CHEMISTRY, ISSN 0959-9428, Vol. 19, nr 30, s. 5359-5363Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    A novel copolymer based on alternating fluorene and donor-acceptor-donor segments is reported, together with its photovoltaic properties in blends with fullerene derivatives. The balanced electron and hole mobility of the blends leads to a power-conversion efficiency of 2-3% under solar illumination.

  • 187.
    George, Zandra
    et al.
    Chalmers, Sweden.
    Xia, Yuxin
    Linköpings universitet, Institutionen för fysik, kemi och biologi. Linköpings universitet, Tekniska fakulteten.
    Sharma, Anirudh
    University of S Australia, Australia.
    Lindqvist, Camilla
    Karlstad University, Sweden.
    Andersson, Gunther
    Flinders University of S Australia, Australia.
    Inganäs, Olle
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Biomolekylär och Organisk Elektronik. Linköpings universitet, Tekniska fakulteten.
    Moons, Ellen
    Karlstad University, Sweden.
    Muller, Christian
    Chalmers, Sweden.
    Andersson, Mats R.
    Chalmers, Sweden; University of S Australia, Australia.
    Two-in-one: cathode modification and improved solar cell blend stability through addition of modified fullerenes2016Ingår i: Journal of Materials Chemistry A, ISSN 2050-7488, Vol. 4, nr 7, s. 2663-2669Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The synthesis of dual purpose modified fullerenes with pyridine-as well as amine-functional groups is reported. Addition of these fullerenes to a polymer : fullerene bulk-heterojunction blend based on a thiophene-quinoxaline donor polymer is found to modify the active layer/cathode interface of inverted solar cells (glass/ITO/active layer/MoO3/Al). In particular the open-circuit voltage of devices is increased from 0.1 V to about 0.7 V, which results in a drastic rise in photovoltaic performance with a power conversion efficiency of up to 3%. At the same time, presence of the functionalised fullerene additives prevents the detrimental formation of micrometre-sized fullerene crystals upon annealing at 140 degrees C. As a result, the device performance is retained, which promises significantly increased thermal stability of the bulk-heterojunction blend nanostructure.

  • 188. Ghosh, S.
    et al.
    Inganäs, Olle
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi, Biomolekylär och Organisk Elektronik.
    Electrochemical characterization of poly(3,4-ethylene dioxythiophene) based conducting hydrogel networks2000Ingår i: Journal of the Electrochemical Society, ISSN 0013-4651, E-ISSN 1945-7111, Vol. 147, nr 5, s. 1872-1877Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Poly(3,4-ethylene dioxythiophene), a conjugated polymer, doped with excess of polystyrenesulfonate (PSS), has been assembled into a mesoscopic conducting network in the form of a hydrogel. When used as an electrode, the material shows fast electrochemical kinetics as evident from cyclic voltammetry, chronopotentiometry, and impedance measurements. Due to high ionic mobility in the material, the electrochemical process is not limited by ion diffusion in the electrode, as normally is the case for conducting polymers, but by the resistance in the electronically conducting network. This resistance is decreased by growing another conducting polymer, polypyrrole (PPy), inside the hydrogel. Homogeneous deposition of PPy is confirmed by atomic force microscopy. The composite hydrogel also shows larger capacitance, only slightly affecting the kinetics of the electrode. Since the material can be charged and discharged in a very short time, application of such electrodes in high power density supercapacitors has been envisaged.

  • 189. Ghosh, S.
    et al.
    Inganäs, Olle
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi, Biomolekylär och Organisk Elektronik.
    Nano-structured conducting polymer network based on PEDOT-PSS2001Ingår i: Synthetic metals, ISSN 0379-6779, E-ISSN 1879-3290, Vol. 121, nr 1-3, s. 1321-1322Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Poly(3,4-ethylenedioxythiophene)-polystyrenesulphonate (PEDOT-PSS) has been crosslinked into network morphology. The morphologies of different crosslinked PEDOT-PSS firms have been characterised by atomic force microscopy (AFM). The crosslinked polymer shows highly efficient and fast redox activity, both in aqueous and non-aqueous media.

  • 190. Ghosh, S.
    et al.
    Inganäs, Olle
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi, Biomolekylär och Organisk Elektronik.
    Networks of electron-conducting polymer in matrices of ion-conducting polymers. Applications to fast electrodes2000Ingår i: Electrochemical and solid-state letters, ISSN 1099-0062, E-ISSN 1944-8775, Vol. 3, nr 5, s. 213-215Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Poly(3,4-ethylenedioxythiophene)-polystyrenesulfonate (PEDOT-PSS), an electronically conductive electroactive polymer, has been blended with an ion conducting polymer, polyethylene oxide (PEO), to increase the ionic mobility in the material. A substantial increase in the current density is observed in the cyclic voltammogram of the PEDOT-PSS, when the latter is blended with PEO. As supercapacitor electrodes, the blends give much higher energy densities at high power densities compared to the pure PEDOT-PSS. This enhancement of electrochemical properties has been ascribed to both intrinsic ionic conductivity of the PEO, and the swelling of the latter in liquid electrolyte solution, creating space for ion movement.

  • 191. Gillissen, S
    et al.
    Jonforsen, M
    Kesters, E
    Johansson, Tomas
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi.
    Theander, M
    Andersson, MR
    Inganäs, Olle
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi, Biomolekylär och Organisk Elektronik.
    Lutsen, L
    Vanderzande, D
    Synthesis and characterization of poly(pyridine vinylene) via the sulfinyl precursor route2001Ingår i: Macromolecules, ISSN 0024-9297, E-ISSN 1520-5835, Vol. 34, nr 21, s. 7294-7299Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The synthesis and characterization of poly(pyridine vinylene) (PPyV) via the nonionic sulfinyl precursor route is presented. Starting from an unsymmetrical monomer, precursor polymers were prepared in various solvents, which led to polymers with variable molecular weights. The thermal conversion to the conjugated structure, as well as its stability, was studied with different techniques such as FT-IR, UV-vis, TGA, and direct insertion probe mass spectroscopy (DIP-MS). From these results we were able to derive the most suitable conditions to perform the conversion. The fully conjugated PPyV was further characterized with photoluminescence (PL) and cyclic voltammetry (CV) measurements. The PL efficiency was found to be as high as 14%. The CV measurements showed that the polymer can be reduced (n-doped).

  • 192.
    Giovanni, David
    et al.
    Nanyang Technol Univ, Singapore; Energy Res Inst NTU ERI N, Singapore.
    Lim, Jia Wei Melvin
    Nanyang Technol Univ, Singapore.
    Yuan, Zhongcheng
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Biomolekylär och Organisk Elektronik. Linköpings universitet, Tekniska fakulteten.
    Lim, Swee Sien
    Nanyang Technol Univ, Singapore.
    Righetto, Marcello
    Nanyang Technol Univ, Singapore.
    Qing, Jian
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Biomolekylär och Organisk Elektronik. Linköpings universitet, Tekniska fakulteten.
    Zhang, Qiannan
    Nanyang Technol Univ, Singapore.
    Dewi, Herlina Arianita
    Energy Res Inst NTU ERI N, Singapore.
    Gao, Feng
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Biomolekylär och Organisk Elektronik. Linköpings universitet, Tekniska fakulteten.
    Mhaisalkar, Subodh Gautam
    Energy Res Inst NTU ERI N, Singapore; Nanyang Technol Univ, Singapore.
    Mathews, Nripan
    Energy Res Inst NTU ERI N, Singapore; Nanyang Technol Univ, Singapore.
    Sum, Tze Chien
    Nanyang Technol Univ, Singapore.
    Ultrafast long-range spin-funneling in solution-processed Ruddlesden-Popper halide perovskites2019Ingår i: Nature Communications, ISSN 2041-1723, E-ISSN 2041-1723, Vol. 10, artikel-id 3456Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Room-temperature spin-based electronics is the vision of spintronics. Presently, there are few suitable material systems. Herein, we reveal that solution-processed mixed-phase Ruddlesden-Popper perovskite thin-films transcend the challenges of phonon momentum-scattering that limits spin-transfer in conventional semiconductors. This highly disordered system exhibits a remarkable efficient ultrafast funneling of photoexcited spin-polarized excitons from two-dimensional (2D) to three-dimensional (3D) phases at room temperature. We attribute this efficient exciton relaxation pathway towards the lower energy states to originate from the energy transfer mediated by intermediate states. This process bypasses the omnipresent phonon momentum-scattering in typical semiconductors with stringent band dispersion, which causes the loss of spin information during thermalization. Film engineering using graded 2D/3D perovskites allows unidirectional out-of-plane spin-funneling over a thickness of similar to 600 nm. Our findings reveal an intriguing family of solution-processed perovskites with extraordinary spin-preserving energy transport properties that could reinvigorate the concepts of spin-information transfer.

  • 193.
    Giuri, Antonella
    et al.
    CNR Nanotec, Italy; Univ Salento, Italy.
    Yuan, Zhongcheng
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Biomolekylär och Organisk Elektronik. Linköpings universitet, Tekniska fakulteten.
    Miao, Yanfeng
    Nanjing Tech Univ Nanjing Tech, Peoples R China.
    Wang, Jianpu
    Nanjing Tech Univ Nanjing Tech, Peoples R China.
    Gao, Feng
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Biomolekylär och Organisk Elektronik. Linköpings universitet, Tekniska fakulteten.
    Sestu, Nicola
    Univ Cagliari, Italy.
    Saba, Michele
    Univ Cagliari, Italy.
    Bongiovanni, Giovanni
    Univ Cagliari, Italy.
    Colella, Silvia
    CNR Nanotec, Italy; Univ Salento, Italy.
    Corcione, Carola Esposito
    Univ Salento, Italy.
    Gigli, Giuseppe
    CNR Nanotec, Italy.
    Listorti, Andrea
    CNR Nanotec, Italy; Univ Salento, Italy.
    Rizzo, Aurora
    CNR Nanotec, Italy.
    Ultra-Bright Near-Infrared Perovskite Light-Emitting Diodes with Reduced Efficiency Roll-off2018Ingår i: Scientific Reports, ISSN 2045-2322, E-ISSN 2045-2322, Vol. 8, artikel-id 15496Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Herein, an insulating biopolymer is exploited to guide the controlled formation of micro/nano-structure and physical confinement of alpha-delta mixed phase crystalline grains of formamidinium lead iodide (FAPbI(3)) perovskite, functioning as charge carrier concentrators and ensuring improved radiative recombination and photoluminescence quantum yield (PLQY). This composite material is used to build highly efficient near-infrared (NIR) FAPbI(3) Perovskite light-emitting diodes (PeLEDs) that exhibit a high radiance of 206.7 W/sr*m(2), among the highest reported for NIR-PeLEDs, obtained at a very high current density of 1000 mA/cm(2), while importantly avoiding the efficiency roll-off effect. In depth photophysical characterization allows to identify the possible role of the biopolymer in i) enhancing the radiative recombination coefficient, improving light extraction by reducing the refractive index, or ii) enhancing the effective optical absorption because of dielectric scattering at the polymer-perovskite interfaces. Our study reveals how the use of insulating matrixes for the growth of perovskites represents a step towards high power applications of PeLEDs.

  • 194.
    Godovsky, D
    et al.
    Linkoping Univ, IFM, Dept Phys, S-58183 Linkoping, Sweden Chalmers Univ Technol, Gothenburg, Sweden Univ Groningen, Stratingh Inst & Mat Sci Ctr, NL-9747 AG Groningen, Netherlands.
    Chen, LC
    Pettersson, Lars
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi.
    Inganäs, Olle
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi, Biomolekylär och Organisk Elektronik.
    Andersson, MR
    Hummelen, JC
    Linkoping Univ, IFM, Dept Phys, S-58183 Linkoping, Sweden Chalmers Univ Technol, Gothenburg, Sweden Univ Groningen, Stratingh Inst & Mat Sci Ctr, NL-9747 AG Groningen, Netherlands.
    The use of combinatorial materials development for polymer solar cells2000Ingår i: Advanced Materials for Optics and Electronics, ISSN 1057-9257, E-ISSN 1099-0712, Vol. 10, nr 2, s. 47-54Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Vile use a combinatorial approach to develop molecular plastic solar cells based on soluble fullerene derivatives blended with conjugated polymers. A combinatorial way of sample preparation is well suited to deal with the multitude of possible combinations of the components of such blends. We use high mobility poly(thiophene) and poly(phenylenevinylene) derivatives to be combined with accepters, Gradients of methanofullerene/polymer concentration were formed by diusion of the low molecular weight component in the spin-cast polymer matrix, Likewise the gradients of zinc phthalocyanine/C-60 were prepared by co-evaporation of the two materials from two sources to make a linear array of photodiode devices, Photo- and electrophysical properties, such as absorption, luminescence, short circuit photocurrent and open circuit photovoltage, were measured using a specially designed installation with a resolution of 70-100 mu. Clear evidence was obtained that the photoconversion efficiency increased with the amount of methanofullerene up to very high levels, in the case of methanofullerene/polymer blends, verifying the important role of the acceptor in the photoconversion. By choosing the optimal ratio between C-60 and ZnPc in the evaporated layer it Is possible to obtain high photocurrent in the 600-700 nm range, due to the added contribution from photoinduced electron transfer between the two molecules, Copyright (C) 2000 John Wiley & Sons, Ltd.

  • 195.
    Goransson, D. J. O.
    et al.
    Lund Univ, Sweden.
    Borgstrom, M. T.
    Lund Univ, Sweden.
    Huang, Yuqing
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Biomolekylär och Organisk Elektronik. Linköpings universitet, Tekniska fakulteten.
    Messing, M. E.
    Lund Univ, Sweden.
    Hessman, D.
    Lund Univ, Sweden.
    Buyanova, Irina A
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Biomolekylär och Organisk Elektronik. Linköpings universitet, Tekniska fakulteten.
    Chen, Weimin
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Biomolekylär och Organisk Elektronik. Linköpings universitet, Tekniska fakulteten.
    Xu, H. Q.
    Lund Univ, Sweden; Peking Univ, Peoples R China; Peking Univ, Peoples R China; Beijing Acad Quantum Informat Sci, Peoples R China.
    Measurements of Strain and Bandgap of Coherently Epitaxially Grown Wurtzite InAsP-InP Core-Shell Nanowires2019Ingår i: Nano letters (Print), ISSN 1530-6984, E-ISSN 1530-6992, Vol. 19, nr 4, s. 2674-2681Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    We report on experimental determination of the strain and bandgap of InAsP in epitaxially grown InAsP-InP core-shell nanowires. The core-shell nanowires are grown via metal-organic vapor phase epitaxy. The as-grown nanowires are characterized by transmission electron microscopy, X-ray diffraction, micro-photoluminescence (mu PL) spectroscopy, and micro-Raman (mu-Raman) spectroscopy measurements. We observe that the core-shell nanowires are of wurtzite (WZ) crystal phase and are coherently strained with the core and the shell having the same number of atomic planes in each nanowire. We determine the predominantly uniaxial strains formed in the core-shell nanowires along the nanowire growth axis and demonstrate that the strains can be described using an analytical expression. The bandgap energies in the strained WZ InAsP core materials are extracted from the mu PL measurements of individual core-shell nanowires. The coherently strained core-shell nanowires demonstrated in this work offer the potentials for use in constructing novel optoelectronic devices and for development of piezoelectric photovoltaic devices.

  • 196.
    Grage, M.M.-L.
    et al.
    Department of Chemical Physics, Lund University, PO Box 124, S-221 00, Lund, Sweden.
    Pullerits, T.
    Department of Chemical Physics, Lund University, PO Box 124, S-221 00, Lund, Sweden.
    Ruseckas, A.
    Department of Chemical Physics, Lund University, PO Box 124, S-221 00, Lund, Sweden.
    Theander, M.
    Inganäs, Olle
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi, Biomolekylär och Organisk Elektronik.
    Sundstrom, V.
    Sundström, V., Department of Chemical Physics, Lund University, PO Box 124, S-221 00, Lund, Sweden.
    Conformational disorder of a substituted polythiophene in solution revealed by excitation transfer2001Ingår i: Chemical Physics Letters, ISSN 0009-2614, E-ISSN 1873-4448, Vol. 339, nr 1-2, s. 96-102Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Anisotropy and isotropic transient absorption decays of a polythiophene derivative in dilute solution have been measured and compared to calculated decays on Monte Carlo simulated polymer chains to obtain knowledge about the geometrical conformation of the polymer. The polymer chain conformations are generated by a partially correlated self-avoiding random walk. Excitation migration along the isolated chain is modeled assuming a hopping mechanism. This approach can be used to determine conformational disorder and possible realizations of the polymer chains in solution as well as the trapping time and migration length of the excitation. © 2001 Elsevier Science B.V.

  • 197.
    Granlund, T
    et al.
    Linkoping Univ, Dept Phys & Measurement Technol, Appl Phys Lab, S-58183 Linkoping, Sweden Chalmers Univ Technol, Dept Organ Chem & Polymer Technol, S-41296 Gothenburg, Sweden.
    Nyberg, Tobias
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi.
    Roman, LS
    Linkoping Univ, Dept Phys & Measurement Technol, Appl Phys Lab, S-58183 Linkoping, Sweden Chalmers Univ Technol, Dept Organ Chem & Polymer Technol, S-41296 Gothenburg, Sweden.
    Svensson, M
    Inganäs, Olle
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi, Biomolekylär och Organisk Elektronik.
    Patterning of polymer light-emitting diodes with soft lithography2000Ingår i: Advanced Materials, ISSN 0935-9648, E-ISSN 1521-4095, Vol. 12, nr 4, s. 269-273Artikel i tidskrift (Refereegranskat)
  • 198.
    Granlund, T
    et al.
    Linkoping Univ, Dept Phys & Measurement Technol, Appl Phys Lab, S-58183 Linkoping, Sweden Chalmers Univ Technol, Dept Organ Chem & Polymer Technol, S-41296 Gothenburg, Sweden.
    Pettersson, Lars
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi.
    Andersson, MR
    Inganäs, Olle
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi, Biomolekylär och Organisk Elektronik.
    Luminescence probing of crystallization in a polymer film2000Ingår i: Journal of Applied Physics, ISSN 0021-8979, E-ISSN 1089-7550, Vol. 87, nr 12, s. 8549-8556Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    We report studies of a thin film multilayer stack including a highly emissive substituted polythiophene, poly[3-(2,5-dioctylphenyl)thiophene]. Analysis of the photoluminescence spectra revealed an inhomogeneous polymer film. X-ray diffraction studies attribute the existence of an inhomogeneous film as originating from crystallization of the polymer. We used the interference effect of light to detect the region of crystallization in the film. Photoluminescence and absorption were redshifted upon crystallization and displayed an enhanced vibronic structure. Comparison between calculated and measured photoluminescence shows that the crystallization starts from the top of the film and not from the supporting substrate. (C) 2000 American Institute of Physics. [S0021- 8979(00)08112-3].

  • 199.
    Granlund, T
    et al.
    Linkoping Univ, Dept Phys & Measurement Technol, Appl Phys Lab, S-58183 Linkoping, Sweden.
    Pettersson, Lars
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi.
    Inganäs, Olle
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi, Biomolekylär och Organisk Elektronik.
    Determination of the emission zone in a single-layer polymer light-emitting diode through optical measurements2001Ingår i: Journal of Applied Physics, ISSN 0021-8979, E-ISSN 1089-7550, Vol. 89, nr 11, s. 5897-5902Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    We study the emission zone in a single-layer polymer light-emitting diode. The emission zone is found by studying the angular distribution of the electroluminescence. The emission is modeled by accounting for optical interference. We account for birefringence of the anode layer in our model. The active polymer was, however, found to be isotropic. The anode consists of a single-layer of the conducting polymer complex poly(3,4-ethylenedioxythiophene) and poly(styrene sulfonate) (PEDOT-PSS), with enhanced conductivity. As a cathode we use plain aluminum. By using only PEDOT-PSS we avoid having a thin metal layer or indium-tin-oxide as the anode in the path of the escaping light. The active material is a substituted polythiophene with excellent film forming properties. A comparison between the experimental and calculated angular distribution of light emission from a single-layered polymer light-emitting diode was shown to be in good agreement for the spectral region studied. By assuming a distribution of the emission zone, we deduce the position as well as the width of the zone. (C) 2001 American Institute of Physics.

  • 200.
    Guo, Yiting
    et al.
    Chinese Acad Sci, Peoples R China; Univ Chinese Acad Sci, Peoples R China.
    Liu, Yanfeng
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Biomolekylär och Organisk Elektronik. Linköpings universitet, Tekniska fakulteten.
    Zhu, Qinglian
    Xi An Jiao Tong Univ, Peoples R China.
    Li, Cheng
    Chinese Acad Sci, Peoples R China.
    Jin, Yingzhi
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Biomolekylär och Organisk Elektronik. Linköpings universitet, Tekniska fakulteten.
    Puttisong, Yuttapoom
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Ytors Fysik och Kemi. Linköpings universitet, Tekniska fakulteten.
    Chen, Weimin
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Ytors Fysik och Kemi. Linköpings universitet, Tekniska fakulteten.
    Liu, Feng
    Hebei Univ, Peoples R China.
    Zhang, Fengling
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Biomolekylär och Organisk Elektronik. Linköpings universitet, Tekniska fakulteten.
    Ma, Wei
    Xi An Jiao Tong Univ, Peoples R China.
    Li, Weiwei
    Chinese Acad Sci, Peoples R China.
    Effect of Side Groups on the Photovoltaic Performance Based on Porphyrin-Perylene Bisimide Electron Acceptors2018Ingår i: ACS Applied Materials and Interfaces, ISSN 1944-8244, E-ISSN 1944-8252, Vol. 10, nr 38, s. 32454-32461Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    In this work, we developed four porphyrin-based small molecular electron acceptors for non-fullerene organic solar cells, in which different side groups attached to the porphyrin core were selected in order to achieve optimized performance. The molecules contain porphyrin as the core, perylene bisimides as end groups, and the ethynyl unit as the linker. Four side groups, from 2,6-di(dodecyloxy)phenyl to (2-ethylhexyl)thiophen-2-yl, pentadecan-7-yl, and 3,5-di(dodecyloxy)phenyl unit, were applied into the electron acceptors. The new molecules exhibit broad absorption spectra from 300 to 900 nm and high molar extinction coefficients. The molecules as electron acceptors were applied into organic solar cells, showing increased power conversion efficiencies from 1.84 to 5.34%. We employed several techniques, including photoluminescence spectra, electroluminescence spectra, atomic force microscopy, and grazing-incidence wide-angle X-ray to probe the blends to find the effects of the side groups on the photovoltaic properties. We found that the electron acceptors with 2,6-di(dodecyloxy)phenyl units show high-lying frontier energy levels, good crystalline properties, and low nonradiative recombination loss, resulting in possible large phase separation and low energy loss, which is responsible for the low performance. Our results provide a detailed study about the side groups of non-fullerene materials, demonstrating that porphyrin can be used to design electron acceptors toward near-infrared absorption.

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