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  • 1.
    Ail, Ujwala
    et al.
    Linköping University, Department of Science and Technology, Laboratory of Organic Electronics. Linköping University, Faculty of Science & Engineering.
    Nilsson, Jakob
    Ligna Energy AB, Sweden.
    Jansson, Mattias
    Linköping University, Department of Physics, Chemistry and Biology, Electronic and photonic materials. Linköping University, Faculty of Science & Engineering.
    Buyanova, Irina A
    Linköping University, Department of Physics, Chemistry and Biology, Electronic and photonic materials. Linköping University, Faculty of Science & Engineering.
    Wu, Zhixing
    Linköping University, Department of Physics, Chemistry and Biology, Nanostructured Materials. Linköping University, Faculty of Science & Engineering.
    Björk, Emma
    Linköping University, Department of Physics, Chemistry and Biology, Nanostructured Materials. Linköping University, Faculty of Science & Engineering.
    Berggren, Magnus
    Linköping University, Department of Science and Technology, Laboratory of Organic Electronics. Linköping University, Faculty of Science & Engineering.
    Crispin, Xavier
    Linköping University, Department of Science and Technology, Laboratory of Organic Electronics. Linköping University, Faculty of Science & Engineering.
    Optimization of Non-Pyrolyzed Lignin Electrodes for Sustainable Batteries2023In: ADVANCED SUSTAINABLE SYSTEMS, ISSN 2366-7486, Vol. 7, no 2, article id 2200396Article in journal (Refereed)
    Abstract [en]

    Lignin, a byproduct from the pulp industry, is one of the redox active biopolymers being investigated as a component in the electrodes for sustainable energy storage applications. Due to its insulating nature, it needs to be combined with a conductor such as carbon or conducting polymer for efficient charge storage. Here, the lignin/carbon composite electrodes manufactured via mechanical milling (ball milling) are reported. The composite formation, correlation between performance and morphology is studied by comparison with manual mixing and jet milling. Superior charge storage capacity with approximate to 70% of the total contribution from the Faradaic process involving the redox functionality of lignin is observed in a mechanically milled composite. In comparison, manual mix shows only approximate to 30% from the lignin storage participation while the rest is due to the electric double layer at the carbon-electrolyte interface. The significant participation of lignin in the ball milled composite is attributed to the homogeneous, intimate mixing of the carbon and the lignin leading the electronic carrier transported in the carbon phase to reach most of the redox group of lignin. A maximum capacity of 49 mAh g(-1) is obtained at charge/discharge rate of 0.25 A g(-1) for the sample milled for 60 min.

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  • 2.
    Ail, Ujwala
    et al.
    Linköping University, Department of Science and Technology, Laboratory of Organic Electronics. Linköping University, Faculty of Science & Engineering.
    Phopase, Jaywant
    Linköping University, Department of Science and Technology, Laboratory of Organic Electronics. Linköping University, Faculty of Science & Engineering.
    Nilsson, Jakob
    Ligna Energy AB, Sweden.
    Khan, Zia
    Linköping University, Department of Science and Technology, Laboratory of Organic Electronics. Linköping University, Faculty of Science & Engineering.
    Inganäs, Olle
    Linköping University, Department of Physics, Chemistry and Biology, Electronic and photonic materials. Linköping University, Faculty of Science & Engineering.
    Berggren, Magnus
    Linköping University, Department of Science and Technology, Laboratory of Organic Electronics. Linköping University, Faculty of Science & Engineering.
    Crispin, Xavier
    Linköping University, Department of Science and Technology, Laboratory of Organic Electronics. Linköping University, Faculty of Science & Engineering.
    Effect of Sulfonation Level on Lignin/Carbon Composite Electrodes for Large-Scale Organic Batteries2020In: ACS Sustainable Chemistry and Engineering, E-ISSN 2168-0485, Vol. 8, no 49, p. 17933-17944Article in journal (Refereed)
    Abstract [en]

    The key figure-of-merit for materials in stationary energy storage applications, such as large-scale energy storage for buildings and grids, is the cost per kilo per electrochemical cycle, rather than the energy density. In this regard, forest-based biopolymers such as lignin, are attractive, as they are abundant on Earth. Here, we explored lignin as an electroactive battery material, able to store two electrons per hydroquinone aromatic ring, with the targeted operation in aqueous electrolytes. The impact of the sulfonation level of lignin on the performance of its composite electrode with carbon was investigated by considering three lignin derivatives: lignosulfonate (LS), partially desulfonated lignosulfonate (DSLS), and fully desulfonated lignin (KL, lignin produced by the kraft process). Partial desulfonation helped in better stability of the composite in aqueous media, simultaneously favoring its water processability. In this way, a route to promote ionic conductivity within the lignin/carbon composite electrodes was developed, facilitating the access to the entire bulk of the volumetric electrodes. Electrochemical performance of DSLS/C showed highly dominant Faradaic contribution (66%) towards the total capacity, indicating an efficient mixed ionic-electronic transport within the lignin-carbon phase, displaying a capacity of 38 mAh/g at 0.25 A/g and 69% of capacity retention after 2200 cycles at a rate of 1 A/g.

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  • 3.
    Ajjan, Fátima
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics. Linköping University, Faculty of Science & Engineering.
    Vagin, Mikhail
    Linköping University, Department of Science and Technology, Laboratory of Organic Electronics. Linköping University, Faculty of Science & Engineering.
    Rebis, Tomasz
    Poznan Univ Tech, Poland.
    Ever Aguirre, Luis
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics. Linköping University, Faculty of Science & Engineering.
    Ouyang, Liangqi
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics. Linköping University, Faculty of Science & Engineering.
    Inganäs, Olle
    Linköping University, Department of Physics, Chemistry and Biology, Electronic and photonic materials. Linköping University, Faculty of Science & Engineering.
    Scalable Asymmetric Supercapacitors Based on Hybrid Organic/Biopolymer Electrodes2017In: ADVANCED SUSTAINABLE SYSTEMS, ISSN 2366-7486, Vol. 1, no 8, article id 1700054Article in journal (Refereed)
    Abstract [en]

    A trihybrid bioelectrode composed of lignin, poly(3,4-ethylenedioxythiophene) (PEDOT), and poly(aminoanthraquinone) (PAAQ) is prepared by a two-step galvanostatic electropolymerization, and characterized for supercapacitor applications. Using PEDOT/Lignin as a base layer, followed by the consecutive deposition of PAAQ, the hybrid electrode PEDOT/Lignin/PAAQ shows a high specific capacitance of 418 F g(-1) with small self-discharge. This trihybrid electrode material can be assembled into symmetric and asymmetric super-capacitors. The asymmetric supercapacitor uses PEDOT + Lignin/PAAQ as positive electrode and PEDOT/PAAQ as negative electrode, and exhibits superior electrochemical performance due to the synergistic effect of the two electrodes, which leads to a specific capacitance of 74 F g(-1). It can be reversibly cycled in the voltage range of 0-0.7 V. More than 80% capacitance is retained after 10 000 cycles. These remarkable features reveal the exciting potential of a full organic energy storage device with long cycle life.

  • 4.
    Ali Ahmad, Syed Ossama
    et al.
    Govt Coll Univ, Pakistan.
    Ashfaq, Atif
    Govt Coll Univ, Pakistan.
    Akbar, Muhammad Usama
    Govt Coll Univ, Pakistan.
    Ikram, Mujtaba
    Univ Punjab, Pakistan.
    Khan, Karim
    Dongguan Univ Technol DGUT, Peoples R China.
    Wang, Feng
    Linköping University, Department of Physics, Chemistry and Biology, Electronic and photonic materials. Linköping University, Faculty of Science & Engineering.
    Ikram, Muhammad
    Govt Coll Univ, Pakistan.
    Mahmood, Asif
    Univ Sydney, Australia.
    Application of two-dimensional materials in perovskite solar cells: recent progress, challenges, and prospective solutions2021In: Journal of Materials Chemistry C, ISSN 2050-7526, E-ISSN 2050-7534, Vol. 9, no 40, p. 14065-14092Article, review/survey (Refereed)
    Abstract [en]

    Perovskite solar cells (per-SCs) with high performance and cost-effective solution processing have been the center of interest for researchers in the past decade. Power conversion efficiencies (PCEs) have been gradually improved up to 25.2% with relatively improved stability, which is an unparalleled progress in all generations of solar cell (SC) technology. However, there are still some prevailing challenges regarding the stability and upscaling of these promising devices. Recently, 2D layered materials (LMs) have been extensively explored to overcome the prevailing challenges of poor stability (under moisture, light soaking and high temperature), halide segregation, hysteresis, involvement of toxic materials (i.e., lead), and upscaling of devices. A critical review addressing the recent developments in the use of 2D materials, especially transition metal dichalcogenides (TMDCs), is hence necessary. The development of novel synthesis and deposition techniques including liquid-metal synthesis and ultrasonic assisted spray pyrolysis has offered more efficient fabrication of 2D-LMs with controlled thickness and morphology. Effective functionalization approaches to increase the dispersability of 2D-LMs in non-polar solvents has boosted their potential application in solar cell technology as well. Moreover, compositing 2D TMDCs with suitable organic/inorganic compounds has enabled superior charge kinetics in all functional parts of per-SCs. In addition, newly developed materials such as graphyne and graphdyine along with 2D metal organic frameworks (MOFs) and covalent organic frameworks (COFs) have been employed in per-SCs to achieve PCEs up to 20%. This review summarizes the recent progress and challenges in the application of 2D-LMs in per-SCs and outlines the future pathways to further extend the PCE of per-SCs beyond 25%. This review particularly focuses on 2D-LMs as electrode materials and additives, the underlying charge (electron-hole) transport phenomenon in the functional layers, and their chemical and structural stability.

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  • 5.
    Alsufyani, Maryam
    et al.
    Univ Oxford, England.
    Stoeckel, Marc-Antoine
    Linköping University, Department of Science and Technology, Laboratory of Organic Electronics. Linköping University, Faculty of Science & Engineering.
    Chen, Xingxing
    King Abdullah Univ Sci & Technol KAUST, Saudi Arabia.
    Thorley, Karl
    Univ Kentucky, KY 40506 USA.
    Hallani, Rawad K.
    King Abdullah Univ Sci & Technol KAUST, Saudi Arabia.
    Puttisong, Yuttapoom
    Linköping University, Department of Physics, Chemistry and Biology, Electronic and photonic materials. Linköping University, Faculty of Science & Engineering.
    Ji, Xudong
    Northwestern Univ, IL 60208 USA.
    Meli, Dilara
    Northwestern Univ, IL 60208 USA.
    Paulsen, Bryan D.
    Northwestern Univ, IL 60208 USA.
    Strzalka, Joseph
    Argonne Natl Lab, IL 60439 USA.
    Regeta, Khrystyna
    King Abdullah Univ Sci & Technol KAUST, Saudi Arabia.
    Combe, Craig
    King Abdullah Univ Sci & Technol KAUST, Saudi Arabia.
    Chen, Hu
    King Abdullah Univ Sci & Technol KAUST, Saudi Arabia.
    Tian, Junfu
    Univ Oxford, England.
    Rivnay, Jonathan
    Northwestern Univ, IL 60208 USA; Northwestern Univ, IL 60611 USA.
    Fabiano, Simone
    Linköping University, Department of Science and Technology, Laboratory of Organic Electronics. Linköping University, Faculty of Science & Engineering.
    McCulloch, Iain
    Univ Oxford, England; King Abdullah Univ Sci & Technol KAUST, Saudi Arabia.
    Lactone Backbone Density in Rigid Electron-Deficient Semiconducting Polymers Enabling High n-type Organic Thermoelectric Performance2022In: Angewandte Chemie International Edition, ISSN 1433-7851, E-ISSN 1521-3773, Vol. 61, no 7, article id e202113078Article in journal (Refereed)
    Abstract [en]

    Three lactone-based rigid semiconducting polymers were designed to overcome major limitations in the development of n-type organic thermoelectrics, namely electrical conductivity and air stability. Experimental and theoretical investigations demonstrated that increasing the lactone group density by increasing the benzene content from 0 % benzene (P-0), to 50 % (P-50), and 75 % (P-75) resulted in progressively larger electron affinities (up to 4.37 eV), suggesting a more favorable doping process, when employing (N-DMBI) as the dopant. Larger polaron delocalization was also evident, due to the more planarized conformation, which is proposed to lead to a lower hopping energy barrier. As a consequence, the electrical conductivity increased by three orders of magnitude, to achieve values of up to 12 S cm and Power factors of 13.2 mu Wm(-1) K-2 were thereby enabled. These findings present new insights into material design guidelines for the future development of air stable n-type organic thermoelectrics.

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  • 6.
    An, Xiaoqiang
    et al.
    Tsinghua Univ, Peoples R China.
    Wei, Tingcha
    Tsinghua Univ, Peoples R China; Nanjing Univ Aeronaut & Astronaut, Peoples R China.
    Ding, Peijia
    Beihang Univ, Peoples R China.
    Liu, Li-Min
    Beihang Univ, Peoples R China.
    Xiong, Lunqiao
    UCL, England.
    Tang, Junwang
    UCL, England.
    Ma, Jiani
    Shanxi Normal Univ, Peoples R China.
    Wang, Feng
    Linköping University, Department of Physics, Chemistry and Biology, Electronic and photonic materials. Linköping University, Faculty of Science & Engineering.
    Liu, Huijuan
    Tsinghua Univ, Peoples R China.
    Qu, Jiuhui
    Tsinghua Univ, Peoples R China.
    Sodium-Directed Photon-Induced Assembly Strategy for Preparing Multisite Catalysts with High Atomic Utilization Efficiency2023In: Journal of the American Chemical Society, ISSN 0002-7863, E-ISSN 1520-5126, Vol. 145, no 3, p. 1759-1768Article in journal (Refereed)
    Abstract [en]

    Integrating different reaction sites offers new prospects to address the difficulties in single-atom catalysis, but the precise regulation of active sites at the atomic level remains challenging. Here, we demonstrate a sodium-directed photon-induced assembly (SPA) strategy for boosting the atomic utilization efficiency of single-atom catalysts (SACs) by constructing multifarious Au sites on TiO2 substrate. Na+ was employed as the crucial cement to direct Au single atoms onto TiO2, while the light-induced electron transfer from excited TiO2 to Au(Na+) ensembles contributed to the self-assembly formation of Au nanoclusters. The synergism between plasmonic near-field and Schottky junction enabled the cascade electron transfer for charge separation, which was further enhanced by oxygen vacancies in TiO2. Our dual-site photocatalysts exhibited a nearly 2 orders of magnitude improvement in the hydrogen evolution activity under simulated solar light, with a striking turnover frequency (TOF) value of 1533 h(-1) that exceeded other Au/TiO2-based photocatalysts reported. Our SPA strategy can be easily extended to prepare a wide range of metal-coupled nanostructures with enhanced performance for diverse catalytic reactions. Thus, this study provides a well-defined platform to extend the boundaries of SACs for multisite catalysis through harnessing metal-support interactions.

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  • 7.
    Andersson, Olof
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Electronic and photonic materials. Linköping University, Faculty of Science & Engineering.
    Kemerink, Martijn
    Linköping University, Department of Physics, Chemistry and Biology, Electronic and photonic materials. Linköping University, Faculty of Science & Engineering. Heidelberg Univ, Germany.
    Enhancing Open-Circuit Voltage in Gradient Organic Solar Cells by Rectifying Thermalization Losses2020In: Solar RRL, E-ISSN 2367-198X, Vol. 4, no 12, article id 2000400Article in journal (Refereed)
    Abstract [en]

    In virtually all solar cells, including optimized ones that operate close to the Shockley-Queisser (SQ) limit, thermalization losses are a major, efficiency-limiting factor. In typical bulk heterojunction organic solar cells, the loss of the excess energy of photocreated charge carriers in the disorder-broadened density of states is a relatively slow process that for commonly encountered disorder values takes longer than the charge extraction time. Herein, it is demonstrated by numerical modeling that this slow relaxation can be rectified by means of a linear gradient in the donor:acceptor ratio between anode and cathode. For experimentally relevant parameters, open-circuit voltage (VOC) enhancements up to approximate to 0.2 V in combination with significant enhancements in fill factor as compared to devices without gradient are found. The VOC enhancement can be understood in terms of a simple nonequilibrium effective temperature model. Implications for existing and future organic photovoltaics (OPV) devices are discussed.

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  • 8.
    Argillander, Joakim
    et al.
    Linköping University, Department of Electrical Engineering, Information Coding. Linköping University, Faculty of Science & Engineering.
    Alarcon, Alvaro
    Linköping University, Department of Electrical Engineering, Information Coding. Linköping University, Faculty of Science & Engineering.
    Bao, Chunxiong
    Linköping University, Department of Physics, Chemistry and Biology, Electronic and photonic materials. Linköping University, Faculty of Science & Engineering. Nanjing Univ, Peoples R China.
    Kuang, Chaoyang
    Linköping University, Faculty of Science & Engineering. Linköping University, Department of Science and Technology, Laboratory of Organic Electronics.
    Lima, Gustavo
    Univ Concepcion, Chile.
    Gao, Feng
    Linköping University, Department of Physics, Chemistry and Biology, Electronic and photonic materials. Linköping University, Faculty of Science & Engineering.
    Xavier, Guilherme B.
    Linköping University, Department of Electrical Engineering, Information Coding. Linköping University, Faculty of Science & Engineering.
    Quantum random number generation based on a perovskite light emitting diode2023In: Communications Physics, E-ISSN 2399-3650, Vol. 6, no 1, article id 157Article in journal (Refereed)
    Abstract [en]

    True random number generation is not thought to be possible using a classical approach but by instead exploiting quantum mechanics genuine randomness can be achieved. Here, the authors demonstrate a certified quantum random number generation using a metal-halide perovskite light emitting diode as a source of weak coherent polarisation states randomly producing an output of either 0 or 1. The recent development of perovskite light emitting diodes (PeLEDs) has the potential to revolutionize the fields of optical communication and lighting devices, due to their simplicity of fabrication and outstanding optical properties. Here we demonstrate that PeLEDs can also be used in the field of quantum technologies by implementing a highly-secure quantum random number generator (QRNG). Modern QRNGs that certify their privacy are posed to replace classical random number generators in applications such as encryption and gambling, and therefore need to be cheap, fast and with integration capabilities. Using a compact metal-halide PeLED source, we generate random numbers, which are certified to be secure against an eavesdropper, following the quantum measurement-device-independent scenario. The obtained generation rate of more than 10 Mbit s(-1), which is already comparable to commercial devices, shows that PeLEDs can work as high-quality light sources for quantum information tasks, thus opening up future applications in quantum technologies.

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  • 9.
    Bai, Yang
    et al.
    Beijing Univ Chem Technol, Peoples R China.
    Zhang, Ze
    Beijing Univ Chem Technol, Peoples R China.
    Zhou, Qiuju
    Xinyang Normal Univ, Peoples R China.
    Geng, Hua
    Capital Normal Univ, Peoples R China.
    Chen, Qi
    Beijing Univ Chem Technol, Peoples R China.
    Kim, Seoyoung
    Ulsan Natl Inst Sci & Technol UNIST, South Korea.
    Zhang, Rui
    Linköping University, Department of Physics, Chemistry and Biology, Electronic and photonic materials. Linköping University, Faculty of Science & Engineering.
    Zhang, Cen
    Beijing Univ Chem Technol, Peoples R China.
    Chang, Bowen
    Beijing Univ Chem Technol, Peoples R China.
    Li, Shangyu
    Beijing Univ Chem Technol, Peoples R China.
    Fu, Hongyuan
    Beijing Univ Chem Technol, Peoples R China.
    Xue, Lingwei
    Beijing Univ Chem Technol, Peoples R China.
    Wang, Haiqiao
    Beijing Univ Chem Technol, Peoples R China.
    Li, Wenbin
    Zhengzhou Univ, Peoples R China; Zhengzhou Univ, Peoples R China.
    Chen, Weihua
    Zhengzhou Univ, Peoples R China; Zhengzhou Univ, Peoples R China.
    Gao, Mengyuan
    Tianjin Univ, Peoples R China.
    Ye, Long
    Tianjin Univ, Peoples R China.
    Zhou, Yuanyuan
    Hong Kong Baptist Univ, Peoples R China; Hong Kong Baptist Univ, Peoples R China.
    Ouyang, Yanni
    Hong Kong Baptist Univ, Peoples R China; Hong Kong Baptist Univ, Peoples R China.
    Zhang, Chunfeng
    Nanjing Univ, Peoples R China; Nanjing Univ, Peoples R China.
    Gao, Feng
    Linköping University, Department of Physics, Chemistry and Biology, Electronic and photonic materials. Linköping University, Faculty of Science & Engineering.
    Yang, Changduk
    Ulsan Natl Inst Sci & Technol UNIST, South Korea.
    Li, Yongfang
    Chinese Acad Sci, Peoples R China.
    Zhang, Zhi-Guo
    Beijing Univ Chem Technol, Peoples R China.
    Geometry design of tethered small-molecule acceptor enables highly stable and efficient polymer solar cells2023In: Nature Communications, E-ISSN 2041-1723, Vol. 14, no 1, article id 2926Article in journal (Refereed)
    Abstract [en]

    With the power conversion efficiency of binary polymer solar cells dramatically improved, the thermal stability of the small-molecule acceptors raised the main concerns on the device operating stability. Here, to address this issue, thiophene-dicarboxylate spacer tethered small-molecule acceptors are designed, and their molecular geometries are further regulated via the thiophene-core isomerism engineering, affording dimeric TDY-alpha with a 2, 5-substitution and TDY-beta with 3, 4-substitution on the core. It shows that TDY-alpha processes a higher glass transition temperature, better crystallinity relative to its individual small-molecule acceptor segment and isomeric counterpart of TDY-beta, and amore stablemorphology with the polymer donor. As a result, the TDY-alpha based device delivers a higher device efficiency of 18.1%, and most important, achieves an extrapolated lifetime of about 35000 hours that retaining 80% of their initial efficiency. Our result suggests that with proper geometry design, the tethered small-molecule acceptors can achieve both high device efficiency and operating stability.

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  • 10.
    Bao, Chunxiong
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Electronic and photonic materials. Linköping University, Faculty of Science & Engineering. Nanjing Univ, Peoples R China.
    Gao, Feng
    Linköping University, Department of Physics, Chemistry and Biology, Electronic and photonic materials. Linköping University, Faculty of Science & Engineering.
    Physics of defects in metal halide perovskites2022In: Reports on progress in physics (Print), ISSN 0034-4885, E-ISSN 1361-6633, Vol. 85, no 9, article id 096501Article, review/survey (Refereed)
    Abstract [en]

    Metal halide perovskites are widely used in optoelectronic devices, including solar cells, photodetectors, and light-emitting diodes. Defects in this class of low-temperature solution-processed semiconductors play significant roles in the optoelectronic properties and performance of devices based on these semiconductors. Investigating the defect properties provides not only insight into the origin of the outstanding performance of perovskite optoelectronic devices but also guidance for further improvement of performance. Defects in perovskites have been intensely studied. Here, we review the progress in defect-related physics and techniques for perovskites. We survey the theoretical and computational results of the origin and properties of defects in perovskites. The underlying mechanisms, functions, advantages, and limitations of trap state characterization techniques are discussed. We introduce the effect of defects on the performance of perovskite optoelectronic devices, followed by a discussion of the mechanism of defect treatment. Finally, we summarize and present key challenges and opportunities of defects and their role in the further development of perovskite optoelectronic devices.

  • 11.
    Beket, Gulzada
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Electronic and photonic materials. Linköping University, Faculty of Science & Engineering. Epishine AB, Linkoping, Sweden.
    Zubayer, Anton
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Zhang, Qilun
    Linköping University, Department of Science and Technology, Laboratory of Organic Electronics. Linköping University, Faculty of Science & Engineering.
    Stahn, Jochen
    Paul Scherer Inst PSI, Switzerland.
    Eriksson, Fredrik
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Fahlman, Mats
    Linköping University, Department of Science and Technology, Laboratory of Organic Electronics. Linköping University, Faculty of Science & Engineering.
    Osterberg, Thomas
    Epishine AB, Linkoping, Sweden.
    Bergqvist, Jonas
    Epishine AB, Linkoping, Sweden.
    Gao, Feng
    Linköping University, Department of Physics, Chemistry and Biology, Electronic and photonic materials. Linköping University, Faculty of Science & Engineering.
    Overcoming the voltage losses caused by the acceptor-based interlayer in laminated indoor OPVs2023In: SMARTMAT, ISSN 2766-8525Article in journal (Refereed)
    Abstract [en]

    Harvesting indoor light to power electronic devices for the Internet of Things has become an application scenario for emerging photovoltaics, especially utilizing organic photovoltaics (OPVs). Combined liquid- and solid-state processing, such as printing and lamination used in industry for developing indoor OPVs, also provides a new opportunity to investigate the device structure, which is otherwise hardly possible based on the conventional approach due to solvent orthogonality. This study investigates the impact of fullerene-based acceptor interlayer on the performance of conjugated polymer-fullerene-based laminated OPVs for indoor applications. We observe open-circuit voltage (V-OC) loss across the interface despite this arrangement being presumed to be ideal for optimal device performance. Incorporating insulating organic components such as polyethyleneimine (PEI) or polystyrene (PS) into fullerene interlayers decreases the work function of the cathode, leading to better energy level alignment with the active layer (AL) and reducing the V-OC loss across the interface. Neutron reflectivity studies further uncover two different mechanisms behind the V-OC increase upon the incorporation of these insulating organic components. The self-organized PEI layer could hinder the transfer of holes from the AL to the acceptor interlayer, while the gradient distribution of the PS-incorporated fullerene interlayer eliminates the thermalization losses. This work highlights the importance of structural dynamics near the extraction interfaces in OPVs and provides experimental demonstrations of interface investigation between solution-processed cathodic fullerene layer and bulk heterojunction AL.

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  • 12.
    Bian, Bian
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Electronic and photonic materials. Linköping University, Faculty of Science & Engineering.
    Musumeci, Chiara
    Linköping University, Department of Science and Technology, Laboratory of Organic Electronics. Linköping University, Faculty of Science & Engineering.
    Wang, Chuan Fei
    Linköping University, Department of Science and Technology, Laboratory of Organic Electronics. Linköping University, Faculty of Science & Engineering.
    Skallberg, Andreas
    Linköping University, Department of Physics, Chemistry and Biology, Molecular Surface Physics and Nano Science. Linköping University, Faculty of Science & Engineering.
    Chen, Yongzhen
    Linköping University, Department of Science and Technology, Laboratory of Organic Electronics. Linköping University, Faculty of Science & Engineering.
    Hu, Zhang-Jun
    Linköping University, Department of Physics, Chemistry and Biology, Molecular Surface Physics and Nano Science. Linköping University, Faculty of Science & Engineering.
    Münger, Peter
    Linköping University, Department of Physics, Chemistry and Biology, Theoretical Physics. Linköping University, Faculty of Science & Engineering.
    Uvdal, Kajsa
    Linköping University, Department of Physics, Chemistry and Biology, Molecular Surface Physics and Nano Science. Linköping University, Faculty of Science & Engineering.
    Fahlman, Mats
    Linköping University, Department of Science and Technology, Laboratory of Organic Electronics. Linköping University, Faculty of Science & Engineering.
    Inganäs, Olle
    Linköping University, Department of Physics, Chemistry and Biology, Electronic and photonic materials. Linköping University, Faculty of Science & Engineering.
    Nanocontacts give efficient hole injection in organic electronics2021In: Science Bulletin, ISSN 2095-9273, Vol. 66, no 9, p. 875-879Article in journal (Other academic)
    Abstract [en]

    n/a

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  • 13.
    Buyanova, Irina A
    et al.
    Linköping University, Faculty of Science & Engineering. Linköping University, Department of Physics, Chemistry and Biology, Electronic and photonic materials.
    Ishikawa, Fumitaro
    Ehime university, Japan.
    Chen, Weimin
    Linköping University, Faculty of Science & Engineering. Linköping University, Department of Physics, Chemistry and Biology, Electronic and photonic materials.
    GaNAs-based nanowires for near-infrared optoelectronics2018In: Novel compound semiconductor nanowires: materials, devices, and applications / [ed] Irina A. Buyanova, Fumutaro Ishikawa, Singapore: Pan Stanford Publishing, 2018, Vol. Sidorna 133-159, p. 133-159Chapter in book (Other academic)
    Abstract [en]

    This chapter analyses the impacts of alloying with nitrogen on structural properties and recombination processes in GaNAs nanowires (NW). It discusses possible innovative applications of these structures in advanced nano-emitters, where the incorporation of nitrogen induces the formation of self-assembled quantum dot-like states embedded in the NWs. The structural properties of these NWs were investigated by transmission electron microcopy. An important material parameter that affects performance of the NW-based devices is carrier lifetime. The non-radiative lifetime is largely affected by the material quality both in bulk and within near-surface regions. The contribution of the surface-related recombination is known to be especially severe in GaAs-based NW structures due to a large surface-to-volume ratio and the presence of surface states participating in the non-radiative recombination processes. The revealed optical properties of the GaNAs-based NW structures may be attractive for future optoelectronic applications in advanced nano-sized light emitters which could be integrated with silicon technology.

  • 14.
    Buyanova, Irina A
    et al.
    Linköping University, Faculty of Science & Engineering. Linköping University, Department of Physics, Chemistry and Biology, Electronic and photonic materials.
    Tu, Charles W.
    University of California, LaJolla.
    Chen, Weimin
    Linköping University, Faculty of Science & Engineering. Linköping University, Department of Physics, Chemistry and Biology, Electronic and photonic materials.
    Novel GaNP nanowires for advanced optoelectronics and photonics2018In: Novel compound semiconductor nanowires: materials, devices, and applications / [ed] Irina A. Buyanova, Fumitaro Ischikawa, Singapore: Pan Stanford Publishing, 2018, Vol. Sidorna 107-132, p. 107-132Chapter in book (Other academic)
    Abstract [en]

    This chapter discusses structural and optical properties of novel GaNP nanowires (NW), as well as their potential for future applications in optoelectronics and photonics. It reviews efforts devoted to the optimization of GaNP-based NWs for future applications in light-emitting devices and discusses the impacts of structural polymorphism on the radiative efficiency and band structure of the material. The chapter shows that GaNP NWs can be utilized as a source of linearly polarized light with the polarization direction that is not determined by dielectric mismatch between the NW and its surrounding. GaNP alloys are novel III–V semiconductors, which have a great potential for applications in amber-red light-emitting diodes and also as an active material in innovative intermediate the band solar cells. NWs grown under the non-optimized conditions usually suffer from various point and structural defects, which degrade the radiative efficiency.

  • 15.
    Cai, Weidong
    Linköping University, Department of Physics, Chemistry and Biology, Electronic and photonic materials. Linköping University, Faculty of Science & Engineering.
    Tunning Multicolor Light Emission in Lead-free Materials2023Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Perovskites are a class of compounds with the general formula ABX3 and becoming increasingly attractive recently. Because this kind of material possesses various advantages such as abundant raw materials, easy synthesis, excellent photoelectric properties, and short production process. As one of the applications for lead-based perovskites, the perovskite solar cells have quickly enhanced their PCE from 3.8% in 2009 to over 25% within a short period. However, the problems, such as instability of the ionic crystal nature and toxicity of lead, largely hinder the lead-based perovskites towards commercialization. Therefore, it is necessary to develop new lead-free materials as alternative to lead-based perovskites, where similar structures can be formed to inherit the excellent optoelectronic properties. Moreover, new properties can be achieved due to more abundant metal candidates in lead-free materials. Based on this, we develop different kinds of perovskite-structure-like lead-free materials such as organic inorganic hybrid materials, chiral materials and double perovskites. In addition to physical and chemical properties like photoluminescence, absorption, structure, etc., we further demonstrate their potential applications according to their unique properties such as multicolor light emission.

    We incorporate chiral MBA (methylbenzylamine) in inorganic metal system to obtain chiral lead-free organic inorganic hybrid materials, where significant crystallization difference is observed between rac and chiral halide compounds for the first time. Such difference is confirmed by spectrum and structural results. What’s more, we find that moisture can cause the structural transfer in chiral compounds, attributed to the asymmetric hydrogen bonding of chiral compounds. Our achievements open up new chance to improve our material property and provide new horizon for synthesis of chiral materials in the future.

    Then, we obtained blue emission center in Mn-based organic and inorganic compounds by choosing organic molecule MBA. The method has basic difference with the emissions in Mn based compounds. The coexisting two emission centers of our Mn based samples is verified by spectral results. Because two emission centers can induce different PL excitation responses, so that the excitation wavelengths are capable of manipulating the emission color. Specifically, we achieve CIE coordinates of (0.33, 0.35) with a white emission. The potential of our materials in anti-counterfeiting and multicolor lighting technology are further demonstrated. Our accomplishments explore a new approach for multicolor emission in Mn based materials.

    We finally obtained Sb3+/Cu+ co-doped Cs2NaInCl6 (CNIC) double perovskite by hydrothermal reaction which exhibits tunable dual emissions with PL quantum efficiency (PLQE) of 78%. Depending on different photoluminescence excitation (PLE) spectra between two emissions, multiple emission colors can be got by manipulating excitation wavelength. Interestingly, emission color gamut can be further tuned through manipulating the feeding ratio of CuI dopant, where warm color and cool color can be achieved separately. We further illustrated the application potential of our co-doped materials in the fileds of multicolor lighting devices and anti-counterfeiting. Our achievements open up a brand-new strategy for wider spectral luminescence of double perovskites and pace up the road for a series of new applications.

    List of papers
    1. Chirality Induced Crystal Structural Difference in Metal Halide Composites
    Open this publication in new window or tab >>Chirality Induced Crystal Structural Difference in Metal Halide Composites
    Show others...
    2022 (English)In: Advanced Optical Materials, ISSN 2162-7568, E-ISSN 2195-1071, Vol. 10, no 16, article id 2102140Article in journal (Refereed) Published
    Abstract [en]

    Incorporating chiral organic compounds into metal halide frames is a common and useful method to introduce chirality in metal halide composites. The structures of resulting racemic and chiral composites are usually considered to be nearly identical owing to similar chemical bonding. In this work, by incorporating chiral MBABr (bromide methylbenzylamine) into an inorganic frame, a significant crystallization difference between the resulting racemic and chiral metal halide composites is observed, as confirmed by both structural and spectroscopic measurements. In addition, the structural transformation in the chiral composites can also be induced by moisture, ascribed to the asymmetric hydrogen bonding in chiral materials. These results provide new insights for the future synthesis of chiral materials and open up new possibilities to advance the materials functionalities.

    Place, publisher, year, edition, pages
    Wiley-V C H Verlag GMBH, 2022
    Keywords
    asymmetric hydrogen bonding; chirality; crystal structure difference; lead-free; moisture
    National Category
    Organic Chemistry
    Identifiers
    urn:nbn:se:liu:diva-185587 (URN)10.1002/adom.202102140 (DOI)000800652500001 ()
    Note

    Funding Agencies|Knut and Alice Wallenberg Foundation [KAW 2019.0082]; Swedish Government Strategic Research Area in Materials Science on Functional Materials at Linkoping University [2009-00971]; China Scholarship Council (CSC)

    Available from: 2022-06-08 Created: 2022-06-08 Last updated: 2023-06-02Bibliographically approved
    2. Multicolor light emission in manganese-based metal halide composites
    Open this publication in new window or tab >>Multicolor light emission in manganese-based metal halide composites
    Show others...
    2022 (English)In: Applied Physics Reviews, E-ISSN 1931-9401, Vol. 9, no 4, article id 041409Article in journal (Refereed) Published
    Abstract [en]

    Manganese-based organic-inorganic metal halide composites have been considered as promising candidates for lead-free emitters. However, in spite of their excellent luminescence properties in green and red regions, blue emission-a critical component for white light generation-from pristine manganese-based composites is currently missing. In this work, we successfully achieve blue luminescence center in manganese-based composites through selecting specific organic component methylbenzylamine (MBA). Our approach is fundamentally different from green and red emission in manganese-based composites, which result from manganese-halide frameworks. The coexistence of different luminescence centers in our manganese-based composites is confirmed by photoluminescence (PL) and photoluminescence excitation (PLE) results. As a result of different photoluminescence excitation responses of different emission centers, the resulting emission color can be tuned with selecting different excitation wavelengths. Specifically, a white light emission can be obtained with Commission Internationale de leclairage coordinates of (0.33, 0.35) upon the 330 nm excitation. We further demonstrate the promise of our manganese-based composites in the anti-counterfeiting technology and multicolor lighting. Our results provide a novel strategy for full-spectral emission in manganese-based organic-inorganic metal halide composites and lay a solid foundation for a range of new applications. (C) 2022 Author(s).

    Place, publisher, year, edition, pages
    AIP Publishing, 2022
    National Category
    Atom and Molecular Physics and Optics
    Identifiers
    urn:nbn:se:liu:diva-190471 (URN)10.1063/5.0108010 (DOI)000890953700001 ()
    Note

    Funding Agencies|Knut and Alice Wallenberg Foundation [Dnr KAW 2019.0082]; Swedish Government Strategic Research Area in Materials Science on Functional Materials at Linkoeping University [2009-00971]; China Scholarship Council (CSC)

    Available from: 2022-12-12 Created: 2022-12-12 Last updated: 2024-02-21
  • 16.
    Cai, Weidong
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Electronic and photonic materials. Linköping University, Faculty of Science & Engineering.
    Kuang, Chaoyang
    Linköping University, Department of Science and Technology, Laboratory of Organic Electronics. Linköping University, Faculty of Science & Engineering.
    Liu, Tianjun
    Linköping University, Department of Physics, Chemistry and Biology, Electronic and photonic materials. Linköping University, Faculty of Science & Engineering.
    Shang, Yuequn
    Linköping University, Department of Physics, Chemistry and Biology, Electronic and photonic materials. Linköping University, Faculty of Science & Engineering.
    Zhang, Jia
    Linköping University, Department of Physics, Chemistry and Biology, Electronic and photonic materials. Linköping University, Faculty of Science & Engineering.
    Qin, Jiajun
    Linköping University, Department of Physics, Chemistry and Biology, Electronic and photonic materials. Linköping University, Faculty of Science & Engineering.
    Gao, Feng
    Linköping University, Department of Physics, Chemistry and Biology, Electronic and photonic materials. Linköping University, Faculty of Science & Engineering.
    Multicolor light emission in manganese-based metal halide composites2022In: Applied Physics Reviews, E-ISSN 1931-9401, Vol. 9, no 4, article id 041409Article in journal (Refereed)
    Abstract [en]

    Manganese-based organic-inorganic metal halide composites have been considered as promising candidates for lead-free emitters. However, in spite of their excellent luminescence properties in green and red regions, blue emission-a critical component for white light generation-from pristine manganese-based composites is currently missing. In this work, we successfully achieve blue luminescence center in manganese-based composites through selecting specific organic component methylbenzylamine (MBA). Our approach is fundamentally different from green and red emission in manganese-based composites, which result from manganese-halide frameworks. The coexistence of different luminescence centers in our manganese-based composites is confirmed by photoluminescence (PL) and photoluminescence excitation (PLE) results. As a result of different photoluminescence excitation responses of different emission centers, the resulting emission color can be tuned with selecting different excitation wavelengths. Specifically, a white light emission can be obtained with Commission Internationale de leclairage coordinates of (0.33, 0.35) upon the 330 nm excitation. We further demonstrate the promise of our manganese-based composites in the anti-counterfeiting technology and multicolor lighting. Our results provide a novel strategy for full-spectral emission in manganese-based organic-inorganic metal halide composites and lay a solid foundation for a range of new applications. (C) 2022 Author(s).

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    fulltext
  • 17.
    Cai, Weidong
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Electronic and photonic materials. Linköping University, Faculty of Science & Engineering.
    Qin, Jiajun
    Linköping University, Department of Physics, Chemistry and Biology, Electronic and photonic materials. Linköping University, Faculty of Science & Engineering.
    Pang, Tiqiang
    Xidian Univ, Peoples R China.
    Cai, Xinyi
    Linköping University, Department of Physics, Chemistry and Biology, Electronic and photonic materials. Linköping University, Faculty of Science & Engineering.
    Jia, Renxu
    Xidian Univ, Peoples R China.
    Gao, Feng
    Linköping University, Department of Physics, Chemistry and Biology, Electronic and photonic materials. Linköping University, Faculty of Science & Engineering.
    Chirality Induced Crystal Structural Difference in Metal Halide Composites2022In: Advanced Optical Materials, ISSN 2162-7568, E-ISSN 2195-1071, Vol. 10, no 16, article id 2102140Article in journal (Refereed)
    Abstract [en]

    Incorporating chiral organic compounds into metal halide frames is a common and useful method to introduce chirality in metal halide composites. The structures of resulting racemic and chiral composites are usually considered to be nearly identical owing to similar chemical bonding. In this work, by incorporating chiral MBABr (bromide methylbenzylamine) into an inorganic frame, a significant crystallization difference between the resulting racemic and chiral metal halide composites is observed, as confirmed by both structural and spectroscopic measurements. In addition, the structural transformation in the chiral composites can also be induced by moisture, ascribed to the asymmetric hydrogen bonding in chiral materials. These results provide new insights for the future synthesis of chiral materials and open up new possibilities to advance the materials functionalities.

    Download full text (pdf)
    fulltext
  • 18.
    Cai, Xia
    et al.
    Fudan Univ, Peoples R China; Shanghai Normal Univ, Peoples R China; Fudan Univ, Peoples R China.
    Liu, Fengcai
    Fudan Univ, Peoples R China; Fudan Univ, Peoples R China.
    Yu, Anran
    Fudan Univ, Peoples R China; Fudan Univ, Peoples R China.
    Qin, Jiajun
    Linköping University, Department of Physics, Chemistry and Biology, Electronic and photonic materials. Linköping University, Faculty of Science & Engineering.
    Hatamvand, Mohammad
    Fudan Univ, Peoples R China; Fudan Univ, Peoples R China.
    Ahmed, Irfan
    Fudan Univ, Peoples R China; Fudan Univ, Peoples R China.
    Luo, Jiayan
    Fudan Univ, Peoples R China; Fudan Univ, Peoples R China.
    Zhang, Yiming
    Fudan Univ, Peoples R China; Fudan Univ, Peoples R China; Fudan Univ, Peoples R China.
    Zhang, Hao
    Fudan Univ, Peoples R China; Fudan Univ, Peoples R China; Fudan Univ, Peoples R China; Fudan Univ, Peoples R China.
    Zhan, Yiqiang
    Fudan Univ, Peoples R China; Fudan Univ, Peoples R China.
    Data-driven design of high-performance MASn(x)Pb(1-x)I(3) perovskite materials by machine learning and experimental realization2022In: Light: Science & Applications, ISSN 2095-5545, E-ISSN 2047-7538, Vol. 11, no 1, article id 234Article in journal (Refereed)
    Abstract [en]

    The photovoltaic performance of perovskite solar cell is determined by multiple interrelated factors, such as perovskite compositions, electronic properties of each transport layer and fabrication parameters, which makes it rather challenging for optimization of device performances and discovery of underlying mechanisms. Here, we propose and realize a novel machine learning approach based on forward-reverse framework to establish the relationship between key parameters and photovoltaic performance in high-profile MASn(x)Pb(1-x)I(3) perovskite materials. The proposed method establishes the asymmetrically bowing relationship between band gap and Sn composition, which is precisely verified by our experiments. Based on the analysis of structural evolution and SHAP library, the rapid-change region and low-bandgap plateau region for small and large Sn composition are explained, respectively. By establishing the models for photovoltaic parameters of working photovoltaic devices, the deviation of short-circuit current and opencircuit voltage with band gap in defective-zone and low-bandgap-plateau regions from Shockley-Queisser theory is captured by our models, and the former is due to the deep-level traps formed by crystallographic distortion and the latter is due to the enhanced susceptibility by increased Sn (4+ )content. The more difficulty for hole extraction than electron is also concluded in the models and the prediction curve of power conversion efficiency is in a good agreement with Shockley-Queisser limit. With the help of search and optimization algorithms, an optimized Sn:Pb composition ratio near 0.6 is finally obtained for high-performance perovskite solar cells, then verified by our experiments. Our constructive method could also be applicable to other material optimization and efficient device development.

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  • 19.
    Chai, Gaoda
    et al.
    Hong Kong Univ Sci & Technol, Peoples R China.
    Zhang, Jianquan
    Hong Kong Univ Sci & Technol, Peoples R China.
    Pan, Mingao
    Hong Kong Univ Sci & Technol, Peoples R China.
    Wang, Zhen
    North Carolina State Univ, NC 27695 USA; North Carolina State Univ, NC 27695 USA.
    Yu, Jianwei
    Linköping University, Department of Physics, Chemistry and Biology, Electronic and photonic materials. Linköping University, Faculty of Science & Engineering.
    Liang, Jiaen
    Hong Kong Univ Sci & Technol, Peoples R China.
    Yu, Han
    Hong Kong Univ Sci & Technol, Peoples R China.
    Chen, Yuzhong
    Hong Kong Univ Sci & Technol, Peoples R China.
    Shang, Ao
    Hong Kong Univ Sci & Technol, Peoples R China.
    Liu, Xiyuan
    Peking Univ, Peoples R China.
    Bai, Fujin
    Hong Kong Univ Sci & Technol, Peoples R China.
    Ma, Ruijie
    Hong Kong Univ Sci & Technol, Peoples R China.
    Chang, Yuan
    Hong Kong Univ Sci & Technol, Peoples R China.
    Luo, Siwei
    Hong Kong Univ Sci & Technol, Peoples R China.
    Zeng, Anping
    Hong Kong Univ Sci & Technol, Peoples R China.
    Zhou, Hang
    Peking Univ, Peoples R China.
    Chen, Kai
    Xi An Jiao Tong Univ, Peoples R China.
    Gao, Feng
    Linköping University, Department of Physics, Chemistry and Biology, Electronic and photonic materials. Linköping University, Faculty of Science & Engineering.
    Ade, Harald
    North Carolina State Univ, NC 27695 USA; North Carolina State Univ, NC 27695 USA.
    Yan, He
    Hong Kong Univ Sci & Technol, Peoples R China; South China Univ Technol, Peoples R China.
    Deciphering the Role of Chalcogen-Containing Heterocycles in Nonfullerene Acceptors for Organic Solar Cells2020In: ACS Energy Letters, E-ISSN 2380-8195, Vol. 5, no 11, p. 3415-3425Article in journal (Refereed)
    Abstract [en]

    The field of organic solar cells has experienced paradigm-shifting changes in recent years because of the emergence of nonfullerene acceptors (NFAs). It is critically important to gain more insight into the structure-property relationship of the emerging A-DAD-A-type NFAs. In this Letter, a family of NFAs named BPF-4F, BPT-4F, and BPS-4F incorporating various chalcogen-containing heterocycles, i.e., furan, thiophene, and selenophene, respectively, was designed and synthesized. These NFAs exhibited dramatic differences in their photovoltaic performances with device efficiencies of 16.8% achieved by the thiophene-based cells, which was much higher than the furan-based ones (12.6%). In addition, the selenophene-based NFA showed a red-shifted absorption relative to the furan- and thiophene-based ones and obtained a decent efficiency of 16.3% owing to an improved J(SC). The reasons why these NFAs performed differently are systematically studied by comparing their optoelectronic properties and film morphology, which provides new understandings of the molecular design of high-performance NFAs.

  • 20.
    Chen, Haiyang
    et al.
    Soochow Univ, Peoples R China.
    Zhang, Rui
    Linköping University, Department of Physics, Chemistry and Biology, Electronic and photonic materials. Linköping University, Faculty of Science & Engineering.
    Chen, Xiaobin
    Soochow Univ, Peoples R China.
    Zeng, Guang
    Soochow Univ, Peoples R China.
    Kobera, Libor
    Czech Acad Sci, Czech Republic.
    Abbrent, Sabina
    Czech Acad Sci, Czech Republic.
    Zhang, Ben
    Soochow Univ, Peoples R China.
    Chen, Weijie
    Soochow Univ, Peoples R China.
    Xu, Guiying
    Soochow Univ, Peoples R China.
    Oh, Jiyeon
    Ulsan Natl Inst Sci & Technol, South Korea.
    Kang, So-Huei
    Ulsan Natl Inst Sci & Technol, South Korea.
    Chen, Shanshan
    Chongqing Univ, Peoples R China.
    Yang, Changduk
    Ulsan Natl Inst Sci & Technol, South Korea.
    Brus, Jiri
    Czech Acad Sci, Czech Republic.
    Hou, Jianhui
    Chinese Acad Sci, Peoples R China.
    Gao, Feng
    Linköping University, Department of Physics, Chemistry and Biology, Electronic and photonic materials. Linköping University, Faculty of Science & Engineering.
    Li, Yaowen
    Soochow Univ, Peoples R China.
    Li, Yongfang
    Soochow Univ, Peoples R China; Chinese Acad Sci, Peoples R China.
    A guest-assisted molecular-organization approach for >17% efficiency organic solar cells using environmentally friendly solvents2021In: Nature Energy, E-ISSN 2058-7546, Vol. 6, no 11, p. 1045-1053Article in journal (Refereed)
    Abstract [en]

    The power conversion efficiencies (PCEs) of laboratory-sized organic solar cells (OSCs), usually processed from low-boiling-point and toxic solvents, have reached high values of over 18%. However, there is usually a notable drop of the PCEs when green solvents are used, limiting practical development of OSCs. Herein, we obtain certificated PCEs over 17% in OSCs processed from a green solvent paraxylene (PX) by a guest-assisted assembly strategy, where a third component (guest) is employed to manipulate the molecular interaction of the binary blend. In addition, the high-boiling-point green solvent PX also enables us to deposit a uniform large-area module (36 cm(2)) with a high efficiency of over 14%. The strong molecular interaction between the host and guest molecules also enhances the operational stability of the devices. Our guest-assisted assembly strategy provides a unique approach to develop large-area and high-efficiency OSCs processed from green solvents, paving the way for industrial development of OSCs. Organic solar cells processed from green solvents are easier to implement in manufacturing yet their efficiency is low. Chen et al. devise a guest molecule to improve the molecular packing, enabling devices with over 17% efficiency.

  • 21.
    Chen, Haoran
    et al.
    Shanghai Jiao Tong Univ, Peoples R China.
    Wang, Yong
    Linköping University, Department of Physics, Chemistry and Biology, Electronic and photonic materials. Linköping University, Faculty of Science & Engineering.
    Fan, Yingping
    Shanghai Jiao Tong Univ, Peoples R China.
    Chen, Yuetian
    Shanghai Jiao Tong Univ, Peoples R China.
    Miao, Yanfeng
    Shanghai Jiao Tong Univ, Peoples R China.
    Qin, Zhixiao
    Shanghai Jiao Tong Univ, Peoples R China.
    Wang, Xingtao
    Shanghai Jiao Tong Univ, Peoples R China.
    Liu, Xiaomin
    Shanghai Jiao Tong Univ, Peoples R China.
    Zhu, Kaicheng
    Shanghai Jiao Tong Univ, Peoples R China.
    Gao, Feng
    Linköping University, Department of Physics, Chemistry and Biology, Electronic and photonic materials. Linköping University, Faculty of Science & Engineering.
    Zhao, Yixin
    Shanghai Jiao Tong Univ, Peoples R China; Shanghai Inst Pollut Control & Ecol Secur, Peoples R China.
    Decoupling engineering of formamidinium-cesium perovskites for efficient photovoltaics2022In: National Science Review, ISSN 2095-5138, Vol. 9, no 10, article id nwac127Article in journal (Refereed)
    Abstract [en]

    Sequential Cs incorporation strategy is developed to decouple crystallization of FACs perovskite with reduced electron-phonon coupling, resulting in highly stable FACs tri-iodide perovskite photovoltaics with record efficiency. Although pure formamidinium iodide perovskite (FAPbI(3)) possesses an optimal gap for photovoltaics, their poor phase stability limits the long-term operational stability of the devices. A promising approach to enhance their phase stability is to incorporate cesium into FAPbI(3). However, state-of-the-art formamidinium-cesium (FA-Cs) iodide perovskites demonstrate much worse efficiency compared with FAPbI(3), limited by the different crystallization dynamics of formamidinium and cesium, which result in poor composition homogeneity and high trap densities. We develop a novel strategy of crystallization decoupling processes of formamidinium and cesium via a sequential cesium incorporation approach. As such, we obtain highly reproducible, highly efficient and stable solar cells based on FA(1)(-)(x)Cs(x)PbI(3) (x = 0.05-0.16) films with uniform composition distribution in the nanoscale and low defect densities. We also revealed a new stabilization mechanism for Cs doping to stabilize FAPbI(3), i.e. the incorporation of Cs into FAPbI(3) significantly reduces the electron-phonon coupling strength to suppress ionic migration, thereby improving the stability of FA-Cs-based devices.

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  • 22.
    Chen, Hongru
    et al.
    Beijing Univ Chem Technol, Peoples R China.
    Zhang, Zhi-Guo
    Beijing Univ Chem Technol, Peoples R China.
    Gao, Feng
    Linköping University, Department of Physics, Chemistry and Biology, Electronic and photonic materials. Linköping University, Faculty of Science & Engineering.
    Solidification of solvent additive for stable binary polymer solar cells with similar to 19% efficiency2023In: SCIENCE CHINA-MATERIALS, ISSN 2095-8226, Vol. 66, no 6, p. 2523-2524Article in journal (Other academic)
  • 23.
    Chen, Mengyun
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Electronic and photonic materials. Linköping University, Faculty of Science & Engineering.
    Zhang, Tiankai
    Linköping University, Department of Physics, Chemistry and Biology, Electronic and photonic materials. Linköping University, Faculty of Science & Engineering.
    Elsukova, Anna
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Hu, Zhang-Jun
    Linköping University, Department of Physics, Chemistry and Biology, Molecular Surface Physics and Nano Science. Linköping University, Faculty of Science & Engineering.
    Zhang, Rui
    Linköping University, Department of Physics, Chemistry and Biology, Electronic and photonic materials. Linköping University, Faculty of Science & Engineering.
    Wang, Yonghong
    Linköping University, Department of Physics, Chemistry and Biology, Electronic and photonic materials. Linköping University, Faculty of Science & Engineering.
    Liu, Xianjie
    Linköping University, Department of Science and Technology, Laboratory of Organic Electronics. Linköping University, Faculty of Science & Engineering.
    Liu, Xiaoke
    Linköping University, Department of Physics, Chemistry and Biology, Electronic and photonic materials. Linköping University, Faculty of Science & Engineering.
    Gao, Feng
    Linköping University, Department of Physics, Chemistry and Biology, Electronic and photonic materials. Linköping University, Faculty of Science & Engineering.
    Kinetically Controlled Synthesis of Quasi-Square CsPbI<sub>3</sub> Nanoplatelets with Excellent Stability2023In: Small, ISSN 1613-6810, E-ISSN 1613-6829Article in journal (Refereed)
    Abstract [en]

    Nanoplatelets (NPLs) share excellent luminescent properties with their symmetric quantum dots counterparts and entail special characters benefiting from the shape, like the thickness-dependent bandgap and anisotropic luminescence. However, perovskite NPLs, especially those based on iodide, suffer from poor spectral and phase stability. Here, stable CsPbI3 NPLs obtained by accelerating the crystallization process in ambient-condition synthesis are reported. By this kinetic control, the rectangular NPLs into quasi-square NPLs are tuned, where enlarged width endows the NPLs with a lower surface-area-to-volume ratio (S/V ratio), leading to lower surficial energy and thus improved endurance against NPL fusion (cause for spectral shift or phase transformation). The accelerated crystallization, denoting the fast nucleation and short period of growth in this report, is enabled by preparing a precursor with complete transformation of PbI2 into intermediates (PbI3-), through an additional iodide supplier (e.g., zinc iodide). The excellent color stability of the materials remains in the light-emitting diodes under various bias stresses.

  • 24.
    Chen, Shangzhi
    et al.
    Linköping University, Department of Science and Technology, Laboratory of Organic Electronics. Linköping University, Faculty of Science & Engineering.
    Petsagkourakis, Ioannis
    Linköping University, Department of Science and Technology, Laboratory of Organic Electronics. Linköping University, Faculty of Science & Engineering.
    Spampinato, Nicoletta
    Univ. Bordeaux, CNRS, Bordeaux INP, LCPO, Pessac, France.
    Kuang, Chaoyang
    Linköping University, Department of Physics, Chemistry and Biology, Electronic and photonic materials. Linköping University, Faculty of Science & Engineering.
    Liu, Xianjie
    Linköping University, Department of Science and Technology, Laboratory of Organic Electronics. Linköping University, Faculty of Science & Engineering.
    Brooke, Robert
    RISE Research Institutes of Sweden, Bio- and Organic Electronics, Norrköping, Sweden.
    Kang, Evan S. H.
    Linköping University, Department of Science and Technology, Laboratory of Organic Electronics. Linköping University, Faculty of Science & Engineering.
    Fahlman, Mats
    Linköping University, Department of Science and Technology, Laboratory of Organic Electronics. Linköping University, Faculty of Science & Engineering.
    Crispin, Xavier
    Linköping University, Department of Science and Technology, Laboratory of Organic Electronics. Linköping University, Faculty of Science & Engineering.
    Pavlopoulou, Eleni
    Univ. Bordeaux, CNRS, Bordeaux INP, LCPO, Pessac, France.
    Jonsson, Magnus
    Linköping University, Department of Science and Technology, Laboratory of Organic Electronics. Linköping University, Faculty of Science & Engineering.
    Unraveling vertical inhomogeneity in vapour phase polymerized PEDOT:Tos films2020In: Journal of Materials Chemistry A, ISSN 2050-7488, Vol. 8, p. 18726-18734Article in journal (Refereed)
    Abstract [en]

    The conducting polymer poly(3,4-ethylenedioxythiophene) (PEDOT) forms a promising alternative to conventional inorganic conductors, where deposition of thin films via vapour phase polymerization (VPP) has gained particular interest owing to high electrical conductivity within the plane of the film. The conductivity perpendicular to the film is typically much lower, which may be related not only to preferential alignment of PEDOT crystallites but also to vertical stratification across the film. In this study, we reveal non-linear vertical microstructural variations across VPP PEDOT:Tos thin films, as well as significant differences in doping level between the top and bottom surfaces. The results are consistent with a VPP mechanism based on diffusion-limited transport of polymerization precursors. Conducting polymer films with vertical inhomogeneity may find applications in gradient-index optics, functionally graded thermoelectrics, and optoelectronic devices requiring gradient doping.

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  • 25.
    Chen, Xian-Kai
    et al.
    Univ Arizona, AZ 85721 USA.
    Qian, Deping
    Linköping University, Department of Physics, Chemistry and Biology, Electronic and photonic materials. Linköping University, Faculty of Science & Engineering.
    Wang, Yuming
    Linköping University, Department of Physics, Chemistry and Biology, Electronic and photonic materials. Linköping University, Faculty of Science & Engineering.
    Kirchartz, Thomas
    Forschungszentrum Julich, Germany; Univ Duisburg Essen, Germany; Univ Duisburg Essen, Germany.
    Tress, Wolfgang
    Zurich Univ Appl Sci, Switzerland.
    Yao, Huifeng
    Chinese Acad Sci, Peoples R China.
    Yuan, Jun
    Linköping University, Department of Physics, Chemistry and Biology, Electronic and photonic materials. Linköping University, Faculty of Science & Engineering. Cent South Univ, Peoples R China.
    Huelsbeck, Markus
    Forschungszentrum Julich, Germany.
    Zhang, Maojie
    Soochow Univ, Peoples R China.
    Zou, Yingping
    Cent South Univ, Peoples R China.
    Sun, Yanming
    Beihang Univ, Peoples R China.
    Li, Yongfang
    Chinese Acad Sci, Peoples R China; Soochow Univ, Peoples R China.
    Hou, Jianhui
    Chinese Acad Sci, Peoples R China.
    Inganäs, Olle
    Linköping University, Department of Physics, Chemistry and Biology, Electronic and photonic materials. Linköping University, Faculty of Science & Engineering.
    Coropceanu, Veaceslav
    Univ Arizona, AZ 85721 USA.
    Bredas, Jean-Luc
    Univ Arizona, AZ 85721 USA.
    Gao, Feng
    Linköping University, Department of Physics, Chemistry and Biology, Electronic and photonic materials. Linköping University, Faculty of Science & Engineering.
    A unified description of non-radiative voltage losses in organic solar cells2021In: Nature Energy, E-ISSN 2058-7546, Vol. 6, no 8, p. 799-806Article in journal (Refereed)
    Abstract [en]

    Organic solar cells based on non-fullerene acceptors have enabled high efficiencies yet their charge dynamics and its impact on the photovoltaic parameters are not fully understood. Now, Chen et al. provide a general description of non-radiative voltage losses in both fullerene and non-fullerene solar cells. Recent advances in organic solar cells based on non-fullerene acceptors (NFAs) come with reduced non-radiative voltage losses (Delta V-nr). Here we show that, in contrast to the energy-gap-law dependence observed in conventional donor:fullerene blends, the Delta V-nr values in state-of-the-art donor:NFA organic solar cells show no correlation with the energies of charge-transfer electronic states at donor:acceptor interfaces. By combining temperature-dependent electroluminescence experiments and dynamic vibronic simulations, we provide a unified description of Delta V-nr for both fullerene- and NFA-based devices. We highlight the critical role that the thermal population of local exciton states plays in low-Delta V-nr systems. An important finding is that the photoluminescence yield of the pristine materials defines the lower limit of Delta V-nr. We also demonstrate that the reduction in Delta V-nr (for example, &lt;0.2 V) can be obtained without sacrificing charge generation efficiency. Our work suggests designing donor and acceptor materials with high luminescence efficiency and complementary optical absorption bands extending into the near-infrared region.

  • 26.
    Chen, Xuehan
    et al.
    Nanjing Univ Sci & Technol, Peoples R China.
    Huang, Jing
    Nanjing Univ Sci & Technol, Peoples R China.
    Gao, Feng
    Linköping University, Department of Physics, Chemistry and Biology, Electronic and photonic materials. Linköping University, Faculty of Science & Engineering.
    Xu, Bo
    Nanjing Univ Sci & Technol, Peoples R China.
    Perspective Phosphine oxide additives for perovskite diodes and solar cells2023In: Chem, ISSN 2451-9308, E-ISSN 2451-9294, Vol. 9, no 3, p. 562-575Article, review/survey (Refereed)
    Abstract [en]

    Lead halide perovskites have been considered promising semicon-ducting materials for next-generation optoelectronic devices due to their solution processability and excellent optoelectronic proper-ties. Device performance of perovskite light-emitting diodes (PeLEDs) and perovskite solar cells (PSCs) has been rapidly devel-oped during the past decade. Very recently, organic molecules containing phosphine oxide groups have emerged as promising ad-ditives and passivators to improve the device performance and sta-bility of both PeLEDs and PSCs. In this perspective, we summarize recent progress in the development of new phosphine-oxide-based additives for PeLEDs and PSCs. The passivation mechanism, molecule design principle, and structure-property relationship of phosphine oxide molecules for PeLEDs and PSCs are systematically discussed and analyzed. Finally, we provide an outlook on the mo-lecular design of novel phosphine oxide compounds for efficient and stable PeLEDs and PSCs in the future.

  • 27.
    Chen, Yang
    et al.
    Natl Univ Singapore, Singapore; Univ Sci & Technol China, Peoples R China.
    Feng, Jiangang
    Nanyang Technol Univ, Singapore; Natl Univ Singapore, Singapore.
    Huang, Yuqing
    Linköping University, Department of Physics, Chemistry and Biology, Electronic and photonic materials. Linköping University, Faculty of Science & Engineering. Nanyang Technol Univ, Singapore.
    Chen, Weijin
    Natl Univ Singapore, Singapore.
    Su, Rui
    Nanyang Technol Univ, Singapore.
    Ghosh, Sanjib
    Beijing Acad Quantum Informat Sci, Peoples R China.
    Hou, Yi
    Natl Univ Singapore, Singapore; Natl Univ Singapore, Singapore.
    Xiong, Qihua
    Beijing Acad Quantum Informat Sci, Peoples R China; Tsinghua Univ, Peoples R China; Frontier Sci Ctr Quantum Informat, Peoples R China.
    Qiu, Cheng-Wei
    Natl Univ Singapore, Singapore.
    Compact spin-valley-locked perovskite emission2023In: Nature Materials, ISSN 1476-1122, E-ISSN 1476-4660Article in journal (Refereed)
    Abstract [en]

    Circularly polarized light sources with free-space directional emission play a key role in chiroptics(1), spintronics(2), valleytronics(3) and asymmetric photocatalysis(4). However, conventional approaches fail to simultaneously realize pure circular polarization, high directionality and large emission angles in a compact emitter. Metal-halide perovskite semiconductors are promising light emitters(5-8), but the absence of an intrinsic spin-locking mechanism results in poor emission chirality. Further, device integration has undermined the efficiency and directionality of perovskite chiral emitters. Here we realize compact spin-valley-locked perovskite emitting metasurfaces where spin-dependent geometric phases are imparted into bound states in the continuum via Brillouin zone folding, and thus, photons with different spins are selectively addressed to opposite valleys. Employing this approach, chiral purity of 0.91 and emission angle of 41.0 degrees are simultaneously achieved, with a beam divergence angle of 1.6 degrees. With this approach, we envisage the realization of chiral light- emitting diodes, as well as the on-chip generation of entangled photon pairs.

  • 28.
    Chen, Yang
    et al.
    Chinese Academy of Sciences Key Laboratory of Mechanical Behavior and Design of Materials, Department of Precision Machinery and Precision Instrumentation, University of Science and Technology of China, Hefei, People’s Republic of China ; Department of Electrical and Computer Engineering, National University of Singapore, Singapore, Singapore.
    Feng, Jiangang
    Department of Electrical and Computer Engineering, National University of Singapore, Singapore, Singapore ; Division of Physics and Applied Physics, School of Physical and Mathematical Sciences, Nanyang Technological University, Singapore, Singapore.
    Huang, Yuqing
    Linköping University, Department of Physics, Chemistry and Biology, Electronic and photonic materials. Linköping University, Faculty of Science & Engineering. Division of Physics and Applied Physics, School of Physical and Mathematical Sciences, Nanyang Technological University, Singapore, Singapore.
    Chen, Weijin
    Department of Electrical and Computer Engineering, National University of Singapore, Singapore, Singapore.
    Su, Rui
    Division of Physics and Applied Physics, School of Physical and Mathematical Sciences, Nanyang Technological University, Singapore, Singapore.
    Ghosh, Sanjib
    Beijing Academy of Quantum Information Sciences, Beijing, People’s Republic of China.
    Hou, Yi
    Department of Chemical and Biomolecular Engineering, National University of Singapore, Singapore, Singapore ; Solar Energy Research Institute of Singapore (SERIS), National University of Singapore, Singapore, Singapore.
    Xiong, Qihua
    Beijing Academy of Quantum Information Sciences, Beijing, People’s Republic of China ; State Key Laboratory of Low-Dimensional Quantum Physics and Department of Physics, Tsinghua University, Beijing, People’s Republic of China ; Frontier Science Center for Quantum Information, Beijing, People’s Republic of China.
    Qiu, Cheng-Wei
    Compact spin-valley-locked perovskite emission2023In: Nature Materials, ISSN 1476-1122, E-ISSN 1476-4660, Vol. 22, no 9, p. 1065-1070Article in journal (Refereed)
    Abstract [en]

    Circularly polarized light sources with free-space directional emission play a key role in chiroptics1, spintronics2, valleytronics3 and asymmetric photocatalysis4. However, conventional approaches fail to simultaneously realize pure circular polarization, high directionality and large emission angles in a compact emitter. Metal-halide perovskite semiconductors are promising light emitters5,6,7,8, but the absence of an intrinsic spin-locking mechanism results in poor emission chirality. Further, device integration has undermined the efficiency and directionality of perovskite chiral emitters. Here we realize compact spin-valley-locked perovskite emitting metasurfaces where spin-dependent geometric phases are imparted into bound states in the continuum via Brillouin zone folding, and thus, photons with different spins are selectively addressed to opposite valleys. Employing this approach, chiral purity of 0.91 and emission angle of 41.0° are simultaneously achieved, with a beam divergence angle of 1.6°. With this approach, we envisage the realization of chiral light-emitting diodes, as well as the on-chip generation of entangled photon pairs.

  • 29.
    Chen, Zhan
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Electronic and photonic materials. Linköping University, Faculty of Science & Engineering. Jinan Univ, Peoples R China.
    Liu, Xiaoke
    Linköping University, Department of Physics, Chemistry and Biology, Electronic and photonic materials. Linköping University, Faculty of Science & Engineering.
    Wang, Heyong
    Linköping University, Department of Physics, Chemistry and Biology, Electronic and photonic materials. Linköping University, Faculty of Science & Engineering.
    Liu, Xianjie
    Linköping University, Department of Science and Technology, Laboratory of Organic Electronics. Linköping University, Faculty of Science & Engineering.
    Hou, Lintao
    Jinan Univ, Peoples R China.
    Gao, Feng
    Linköping University, Department of Physics, Chemistry and Biology, Electronic and photonic materials. Linköping University, Faculty of Science & Engineering.
    Photoluminescence Enhancement for Efficient Mixed-Halide Blue Perovskite Light-Emitting Diodes2023In: Advanced Optical Materials, ISSN 2162-7568, E-ISSN 2195-1071Article in journal (Refereed)
    Abstract [en]

    The development of highly efficient blue perovskite light-emitting diodes (PeLEDs) remains a big challenge, requiring more fundamental investigations. In this work, significant photoluminescence enhancement in mixed halide blue perovskite films is demonstrated by using a molecule, benzylphosphonic acid, which eventually doubles the external quantum efficiency to 6.3% in sky-blue PeLEDs. The photoluminescence enhancement is achieved by forming an oxide-bonded perovskite surface at grain boundaries and suppressing electron-phonon interaction, which enhances the radiative recombination rate and reduces the nonradiative recombination rate, respectively. Moreover, severe thermal quenching is observed in the blue perovskite films, which can be explained by a two-step mechanism involving exciton dissociation and electron-phonon interaction. The results suggest that enhancing the radiative recombination rate and reducing the electron-phonon interaction-induced nonradiative recombination rate are crucial for achieving blue perovskite films with strong emission at or above room temperature.

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  • 30.
    Chu, Ming
    et al.
    Fudan Univ, Peoples R China.
    Liu, Shao-Bo
    Fudan Univ, Peoples R China.
    Yu, An-Ran
    Fudan Univ, Peoples R China.
    Yu, Hao-Miao
    Beijing Jiaotong Univ, Peoples R China.
    Qin, Jiajun
    Linköping University, Department of Physics, Chemistry and Biology, Electronic and photonic materials. Linköping University, Faculty of Science & Engineering.
    Yi, Rui-Chen
    Fudan Univ, Peoples R China.
    Pei, Yuan
    Fudan Univ, Peoples R China.
    Zhu, Chun-Qin
    Fudan Univ, Peoples R China.
    Zhu, Guang-Rui
    Fudan Univ, Peoples R China.
    Zeng, Qi
    Shanghai Univ Engn Sci, Peoples R China.
    Hou, Xiao-Yuan
    Fudan Univ, Peoples R China.
    Accurate capacitance-voltage characterization of organic thin films with current injection*2021In: Chinese Physics B, ISSN 1674-1056, Vol. 30, no 8, article id 087301Article in journal (Refereed)
    Abstract [en]

    To deal with the invalidation of commonly employed series model and parallel model in capacitance-voltage (C-V) characterization of organic thin films when current injection is significant, a three-element equivalent circuit model is proposed. On this basis, the expression of real capacitance in consideration of current injection is theoretically derived by small-signal analysis method. The validity of the proposed equivalent circuit and theoretical expression are verified by a simulating circuit consisting of a capacitor, a diode, and a resistor. Moreover, the accurate C-V characteristic of an organic thin film device is obtained via theoretical correction of the experimental measuring result, and the real capacitance is 35.7% higher than the directly measured capacitance at 5-V bias in the parallel mode. This work strongly demonstrates the necessity to consider current injection in C-V measurement and provides a strategy for accurate C-V characterization experimentally.

  • 31.
    Clarke, Andrew J.
    et al.
    Swansea Univ, Wales.
    Luke, Joel
    Imperial Coll London, England; Imperial Coll London, England.
    Meitzner, Rico
    Friedrich Schiller Univ Jena, Germany.
    Wu, Jiaying
    Imperial Coll London, England; Imperial Coll London, England.
    Wang, Yuming
    Linköping University, Department of Physics, Chemistry and Biology, Electronic and photonic materials. Linköping University, Faculty of Science & Engineering.
    Lee, Harrison K. H.
    Swansea Univ, Wales.
    Speller, Emily M.
    Swansea Univ, Wales.
    Bristow, Helen
    Univ Oxford, England.
    Cha, Hyojung
    Imperial Coll London, England; Imperial Coll London, England.
    Newman, Michael J.
    Swansea Univ, Wales.
    Hooper, Katherine
    Swansea Univ, Wales.
    Evans, Alex
    Cardiff Univ, Wales.
    Gao, Feng
    Linköping University, Department of Physics, Chemistry and Biology, Electronic and photonic materials. Linköping University, Faculty of Science & Engineering.
    Hoppe, Harald
    Friedrich Schiller Univ Jena, Germany.
    McCulloch, Iain
    Univ Oxford, England; King Abdullah Univ Sci & Technol KAUST, Saudi Arabia.
    Schubert, Ulrich S.
    Friedrich Schiller Univ Jena, Germany; Friedrich Schiller Univ Jena, Germany.
    Watson, Trystan M.
    Swansea Univ, Wales.
    Durrant, James R.
    Swansea Univ, Wales; Imperial Coll London, England; Imperial Coll London, England.
    Tsoi, Wing C.
    Swansea Univ, Wales.
    Kim, Ji-Seon
    Imperial Coll London, England; Imperial Coll London, England.
    Li, Zhe
    Queen Mary Univ London, England.
    Non-fullerene acceptor photostability and its impact on organic solar cell lifetime2021In: Cell Reports Physical Science, E-ISSN 2666-3864, Vol. 2, no 7, article id 100498Article in journal (Refereed)
    Abstract [en]

    The development of non-fullerene acceptors (NFAs) has facilitated the realization of efficient organic solar cells (OSCs) with minimal burn-in losses and excellent long-term stability. However, the role of NFA molecular structures on device stability remains unclear, limiting commercialization of NFA-based OSCs. Herein, the photostability of 10 OSC devices, fabricated with various NFAs (O-IDTBR, EH-IDTBR, ITIC, and ITIC-M) blended with donor polymers (PTB7-Th, PffBT4T-2OD, and PBDB-T), is investigated. O-IDTBR and EH-IDTBR form highly stable devices with all three polymers, whereas ITIC and ITIC-M devices suffer from burn-in losses and long-term degradation. Conformational instability is found to be responsible for the poor photostability of ITIC and ITIC-M, resulting in poor device stability. Twisting and potential breakage of the chemical bond that links the end group to the main backbone of ITIC and ITIC-M molecules causes undesirable conformational changes. Potential strategies to overcome such detrimental photo-induced conformational changes in NFAs are proposed.

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  • 32.
    Cooke, David G.
    et al.
    McGill Univ, Canada.
    Lan, Yang
    McGill Univ, Canada.
    Dringoli, Benjamin J.
    McGill Univ, Canada.
    Valverde-Chavez, David A.
    McGill Univ, Canada.
    Ponseca, Carlito
    Linköping University, Department of Physics, Chemistry and Biology, Electronic and photonic materials. Linköping University, Faculty of Science & Engineering.
    Sutton, Mark
    McGill Univ, Canada.
    He, Yihui
    Northwestern Univ, IL 60208 USA.
    Kanatzidis, Mercouri G.
    Northwestern Univ, IL 60208 USA.
    Dynamic THz signatures of charge-lattice correlations2020In: 2020 45TH INTERNATIONAL CONFERENCE ON INFRARED, MILLIMETER, AND TERAHERTZ WAVES (IRMMW-THZ), IEEE , 2020Conference paper (Refereed)
    Abstract [en]

    The hybrid metal halide perovskites have shown enormous promise for optoelectronic devices, including efficient photovoltaics, however their insensitivity to defects has remained puzzling. Polaron correlations have been cited as a possible means to protect charge carriers from defect scattering. In this paper, we show time-resolved THz spectroscopy measurements are capable of directly probing polaron correlations via an intra-band coherent beat arising from center-of-mass quasi-particle motion and the internal motion of charge within its self-induced potential. We describe these measurements indicating that charge carriers do indeed exist as polarons, which are coherent for several hundred femtoseconds following photon absorption.

  • 33.
    Cui, Yong
    et al.
    Chinese Acad Sci, Peoples R China.
    Hong, Ling
    Chinese Acad Sci, Peoples R China; Univ Chinese Acad Sci, Peoples R China.
    Zhang, Tao
    Chinese Acad Sci, Peoples R China.
    Meng, Haifeng
    Natl Inst Metrol, Peoples R China.
    Yan, He
    Hong Kong Univ Sci & Technol, Peoples R China.
    Gao, Feng
    Linköping University, Department of Physics, Chemistry and Biology, Electronic and photonic materials. Linköping University, Faculty of Science & Engineering.
    Hou, Jianhui
    Chinese Acad Sci, Peoples R China; Univ Chinese Acad Sci, Peoples R China.
    Accurate photovoltaic measurement of organic cells for indoor applications2021In: Joule, E-ISSN 2542-4351, Vol. 5, no 5, p. 1016-1023Article in journal (Other academic)
    Abstract [en]

    Photovoltaic (PV) cells offer a convenient energy source to drive micropower electronic devices for indoor applications. However, it is challenging to measure the power conversion efficiency (PCE) of PV cells under indoor lighting and the PV community lacks a feasible and accurate measurement protocol. Here, we start with the fundamental parameters which determine the PCE, and carefully design a series of experiments to examine the origins which might cause measurement errors for organic PV measurements under indoor lighting. We demonstrate the critical importance of: 1, temporal stability and spatial homogeneity of the light sources, 2, calibration of the spectral irradiance and illuminations of the light sources, 3, the area of the cells (1 cm2 or large cells are preferred), 4, the aperture of the mask (an aperture slightly smaller than the cell area is preferred), and 5, stray lights from the measurement environment. Based on these careful investigations, we suggest a feasible measurement method, by which accurate measurement of the indoor PV efficiency is made possible. Our study will promote the healthy development of indoor PV technology for practical applications.

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  • 34.
    Du, Siying
    et al.
    Hunan Univ Sci & Technol, Peoples R China.
    Yao, Nannan
    Linköping University, Department of Physics, Chemistry and Biology, Electronic and photonic materials. Linköping University, Faculty of Science & Engineering.
    Liu, Shungang
    Hunan Univ Sci & Technol, Peoples R China.
    Xu, Yongzhuo
    Hunan Univ Sci & Technol, Peoples R China.
    Cao, Jiamin
    Hunan Univ Sci & Technol, Peoples R China; Chalmers Univ Technol, Sweden.
    Zhuang, Wenliu
    Chalmers Univ Technol, Sweden; Guangdong Ind Polytech, Peoples R China.
    Yu, Junting
    Hunan Univ Sci & Technol, Peoples R China.
    Wang, Nong
    Chalmers Univ Technol, Sweden; Lanzhou Jiaotong Univ, Peoples R China.
    Yu, Donghong
    Changsha Univ Sci & Technol, Peoples R China; Changsha Univ Sci & Technol, Peoples R China; Aalborg Univ, Denmark.
    Zhang, Fengling
    Linköping University, Department of Physics, Chemistry and Biology, Electronic and photonic materials. Linköping University, Faculty of Science & Engineering.
    Wang, Ergang
    Chalmers Univ Technol, Sweden; Zhengzhou Univ, Peoples R China.
    Nonfullerene acceptors from thieno[3,2-b]thiophene-fused naphthalene donor core with six-member-ring connection for efficient organic solar cells2021In: Dyes and pigments, ISSN 0143-7208, E-ISSN 1873-3743, Vol. 185, article id 108892Article in journal (Refereed)
    Abstract [en]

    Comprehensive design ideas on the fused-ring donor-core in state-of-the-art acceptor-donor-acceptor (A-D-A) nonfullerene acceptors (NFAs) are still of great importance for regulating the electron push-pull effect for the sake of optimal light-harvesting, frontier molecular orbital levels, and finally their photovoltaic properties. Herein, thieno[3,2-b]thiophenes were fused in bay-area of naphthalene via six-member-ring connection, resulting in the formation of dihydropyrenobisthieno[3,2-b]thiophene based octacyclic ladder-type donor core, which was flanked by two 1,1-dicyanomethylene-3-indanone (IC) acceptor motifs with and without 5,6-diflourination, namely PTT-IC and PTT-2FIC, respectively, as novel efficient A-D-A fused-ring electron acceptors (FREAs). Compared with PTT-IC, fluorinated PTT-2FIC possesses narrower optical bandgap of 1.48 eV, better pi-pi stacking, and its PBDB-T:PTT-2FIC blend film exhibited better morphology, and better hole and electron mobility. As a result, nonfullerene solar cells using PBDB-T:PTT-2FIC as the active layer achieved a decent PCE of 10.40%, with an open-circuit voltage (V-OC) of 0.87 V, a fill factor (FF) of 0.65, and a much higher short-circuit current (J(SC)) of 18.26 mA/cm(2). Meanwhile, the PBDB-T:PTT-IC cells delivered a lower J(SC) of 12.58 mA/cm(2) but a higher V-OC of 0.99 V, thus resulting in a PCE of 7.39% due to its wider optical bandgap of 1.58 eV and higher LUMO energy level. These results demonstrated that NFAs based on fused-ring donor core from fusing thieno [3,2-b]thiophenes with naphthalene via six-member-ring connection are promising for organic photovoltaic applications.

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  • 35.
    Dávid, Anna
    et al.
    Linköping University, Department of Science and Technology, Laboratory of Organic Electronics. Linköping University, Faculty of Science & Engineering.
    Morat, Julia
    Linköping University, Department of Physics, Chemistry and Biology, Electronic and photonic materials. Linköping University, Faculty of Science & Engineering.
    Chen, Mengyun
    Linköping University, Department of Physics, Chemistry and Biology, Electronic and photonic materials. Linköping University, Faculty of Science & Engineering.
    Gao, Feng
    Linköping University, Department of Physics, Chemistry and Biology, Electronic and photonic materials. Linköping University, Faculty of Science & Engineering.
    Fahlman, Mats
    Linköping University, Department of Science and Technology, Laboratory of Organic Electronics. Linköping University, Faculty of Science & Engineering.
    Liu, Xianjie
    Linköping University, Department of Science and Technology, Laboratory of Organic Electronics. Linköping University, Faculty of Science & Engineering.
    Mapping Uncharted Lead-Free Halide Perovskites and Related Low-Dimensional Structures2024In: Materials, E-ISSN 1996-1944, Vol. 17, no 2, article id 491Article, review/survey (Refereed)
    Abstract [en]

    Research on perovskites has grown exponentially in the past decade due to the potential of methyl ammonium lead iodide in photovoltaics. Although these devices have achieved remarkable and competitive power conversion efficiency, concerns have been raised regarding the toxicity of lead and its impact on scaling up the technology. Eliminating lead while conserving the performance of photovoltaic devices is a great challenge. To achieve this goal, the research has been expanded to thousands of compounds with similar or loosely related crystal structures and compositions. Some materials are "re-discovered", and some are yet unexplored, but predictions suggest that their potential applications may go beyond photovoltaics, for example, spintronics, photodetection, photocatalysis, and many other areas. This short review aims to present the classification, some current mapping strategies, and advances of lead-free halide double perovskites, their derivatives, lead-free perovskitoid, and low-dimensional related crystals.

  • 36.
    Erickson, Roland
    et al.
    Linköping University, Department of Physics, Chemistry and Biology. Linköping University, Faculty of Science & Engineering. FMV, Linkoping, Sweden.
    Lund, Anders
    Linköping University, Department of Physics, Chemistry and Biology, Electronic and photonic materials. Linköping University, Faculty of Science & Engineering.
    A comparative analysis of powder ENDOR spectra of aromatic and aliphatic radicals by exact and 1st order simulation2022In: Chemical Physics, ISSN 0301-0104, E-ISSN 1873-4421, Vol. 560, article id 111553Article in journal (Refereed)
    Abstract [en]

    Exact and perturbation methods were employed in simulations of powder ENDOR spectra to obtain the anisotropic hyperfine (hfc) and nuclear quadrupole (nqc) coupling constants of certain organic radicals of interest in fundamental research and in applications in radiation research, surface chemistry and biophysics. The principal hfc values of the ring protons and methyl substituents for several aromatic cations trapped in disordered matrices might be more accurate than those previously reported using regular EPR. Only one of the earlier assignments of the naphthalene cation spectrum was in acceptable agreement with the simulations. The proton couplings at the beta-position of alkyl radicals were deduced by simulations while the spectrum due to alpha-couplings with appreciable anisotropy was weak. Accurate simulation of the 14N (I = 1) spectra in bio-radicals was obtained by adjustment of the relative orientation of the principal hfc and nuclear quadrupole coupling (nqc) tensors as well as the principal values. Adjustment of the excitation width parameter employed in the software was also required in a few cases to improve the agreement with the experimental spectra. The hfc patterns due to matrix nuclei (1H and 7Li) around the radicals of X-irradiated samples were simulated to elucidate the nature of the trapping sites in materials used for EPR dosimetry. ENDOR simulation programs known to us are presented in an Appendix. The performance of the ENDORF2 program used in previous works was examined by comparison with exact treatment. Input and output examples, source and executable codes used in this work can be downloaded at https://github.com/EndorF2/Simulation.

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  • 37.
    Fan, Baobing
    et al.
    City Univ Hong Kong, Peoples R China; City Univ Hong Kong, Peoples R China.
    Gao, Wei
    City Univ Hong Kong, Peoples R China; City Univ Hong Kong, Peoples R China.
    Zhang, Rui
    Linköping University, Department of Physics, Chemistry and Biology, Electronic and photonic materials. Linköping University, Faculty of Science & Engineering.
    Kaminsky, Werner
    Univ Washington, WA 98195 USA.
    Lin, Francis R.
    City Univ Hong Kong, Peoples R China; City Univ Hong Kong, Peoples R China.
    Xia, Xinxin
    Chinese Univ Hong Kong, Peoples R China.
    Fan, Qunping
    Xi An Jiao Tong Univ, Peoples R China.
    Li, Yanxun
    City Univ Hong Kong, Peoples R China; City Univ Hong Kong, Peoples R China.
    An, Yidan
    City Univ Hong Kong, Peoples R China; City Univ Hong Kong, Peoples R China.
    Wu, Yue
    City Univ Hong Kong, Peoples R China; City Univ Hong Kong, Peoples R China.
    Liu, Ming
    City Univ Hong Kong, Peoples R China; City Univ Hong Kong, Peoples R China.
    Lu, Xinhui
    Chinese Univ Hong Kong, Peoples R China.
    Li, Wen Jung
    City Univ Hong Kong, Peoples R China.
    Yip, Hin-Lap
    City Univ Hong Kong, Peoples R China; City Univ Hong Kong, Peoples R China.
    Gao, Feng
    Linköping University, Department of Physics, Chemistry and Biology, Electronic and photonic materials. Linköping University, Faculty of Science & Engineering.
    Jen, Alex K. -Y.
    City Univ Hong Kong, Peoples R China; City Univ Hong Kong, Peoples R China; City Univ Hong Kong, Peoples R China; Univ Washington, WA 98195 USA.
    Correlation of Local Isomerization Induced Lateral and Terminal Torsions with Performance and Stability of Organic Photovoltaics2023In: Journal of the American Chemical Society, ISSN 0002-7863, E-ISSN 1520-5126, Vol. 145, no 10, p. 5909-5919Article in journal (Refereed)
    Abstract [en]

    Organic photovoltaics (OPVs) have achieved great progress in recent years due to delicately designed non-fullerene acceptors (NFAs). Compared with tailoring of the aromatic heterocycles on the NFA backbone, the incorporation of conjugated side-groups is a cost-effective way to improve the photoelectrical properties of NFAs. However, the modifications of side-groups also need to consider their effects on device stability since the molecular planarity changes induced by side-groups are related to the NFA aggregation and the evolution of the blend morphology under stresses. Herein, a new class of NFAs with localisomerized conjugated side-groups are developed and the impact of local isomerization on their geometries and device performance/stability are systematically investigated. The device based on one of the isomers with balanced side- and terminal-group torsion angles can deliver an impressive power conversion efficiency (PCE) of 18.5%, with a low energy loss (0.528 V) and an excellent photo- and thermal stability. A similar approach can also be applied to another polymer donor to achieve an even higher PCE of 18.8%, which is among the highest efficiencies obtained for binary OPVs. This work demonstrates the effectiveness of applying local isomerization to fine-tune the side-group steric effect and non-covalent interactions between side-group and backbone, therefore improving both photovoltaic performance and stability of fused ring NFA-based OPVs.

  • 38.
    Fan, Baobing
    et al.
    City Univ Hong Kong, Peoples R China.
    Gao, Wei
    City Univ Hong Kong, Peoples R China.
    Zhang, Rui
    Linköping University, Department of Physics, Chemistry and Biology, Electronic and photonic materials. Linköping University, Faculty of Science & Engineering.
    Kaminsky, Werner
    Univ Washington, WA 98195 USA.
    Tang, Lingxiao
    Xi An Jiao Tong Univ, Peoples R China.
    Lin, Francis R.
    City Univ Hong Kong, Peoples R China.
    Wang, Yiwen
    City Univ Hong Kong, Peoples R China.
    Fan, Qunping
    Xi An Jiao Tong Univ, Peoples R China.
    Ma, Wei
    Xi An Jiao Tong Univ, Peoples R China.
    Gao, Feng
    Linköping University, Department of Physics, Chemistry and Biology, Electronic and photonic materials. Linköping University, Faculty of Science & Engineering.
    Jen, Alex K. -Y.
    City Univ Hong Kong, Peoples R China; Univ Washington, WA 98195 USA.
    Correlation of Broad Absorption Band with Small Singlet-Triplet Energy Gap in Organic Photovoltaics2023In: Angewandte Chemie International Edition, ISSN 1433-7851, E-ISSN 1521-3773Article in journal (Refereed)
    Abstract [en]

    Organic photovoltaics (OPV) are one of the most effective ways to harvest renewable solar energy, with the power conversion efficiency (PCE) of the devices soaring above 19% when processed with halogenated solvents. The superior photocurrent of OPV over other emerging photovoltaics offers more opportunities to further improve the efficiency. Tailoring the absorption band of photoactive materials is an effective way to further enhance OPV photocurrent. However, the field has mostly been focusing on improving the near-infrared region photo-response, with the absorption shoulders in short-wavelength region (SWR) usually being neglected. Herein, by developing a series of non-fullerene acceptors (NFAs) with varied side-group conjugations, we observe an enhanced SWR absorption band with increased side-group conjugation length. The underpinning factors of how molecular structures and geometries improve SWR absorption are clearly elucidated through theoretical modelling and crystallography. Moreover, a clear relationship between the enhanced SWR absorption and reduced singlet-triplet energy gap is established, both of which are favorable for the OPV performance and can be tailored by rational structure design of NFAs. Finally, the rationally designed NFA, BO-TTBr, affords a decent PCE of 18.5% when processed with a non-halogenated green solvent.

  • 39.
    Fan, Qunping
    et al.
    Chalmers Univ Technol, Sweden.
    An, Qiaoshi
    Beijing Inst Technol, Peoples R China.
    Lin, Yuanbao
    King Abdullah Univ Sci & Technol KAUST, Saudi Arabia.
    Xia, Yuxin
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics. Linköping University, Faculty of Science & Engineering.
    Li, Qian
    Nanjing Univ, Peoples R China.
    Zhang, Ming
    Shanghai Jiao Tong Univ, Peoples R China.
    Su, Wenyan
    Chalmers Univ Technol, Sweden; Jinan Univ, Peoples R China; Karlstad Univ, Sweden.
    Peng, Wenhong
    Chalmers Univ Technol, Sweden; Changzhou Univ, Peoples R China.
    Zhang, Chunfeng
    Nanjing Univ, Peoples R China.
    Liu, Feng
    Shanghai Jiao Tong Univ, Peoples R China.
    Hou, Lintao
    Jinan Univ, Peoples R China.
    Zhu, Weiguo
    Changzhou Univ, Peoples R China.
    Yu, Donghong
    Aalborg Univ, Denmark; Sino Danish Ctr Educ & Res, Denmark.
    Xiao, Min
    Nanjing Univ, Peoples R China.
    Moons, Ellen
    Karlstad Univ, Sweden.
    Zhang, Fujun
    Beijing Jiaotong Univ, Peoples R China.
    Anthopoulos, Thomas D.
    King Abdullah Univ Sci & Technol KAUST, Saudi Arabia.
    Inganäs, Olle
    Linköping University, Department of Physics, Chemistry and Biology, Electronic and photonic materials. Linköping University, Faculty of Science & Engineering.
    Wang, Ergang
    Chalmers Univ Technol, Sweden; Zhengzhou Univ, Peoples R China.
    Over 14% efficiency all-polymer solar cells enabled by a low bandgap polymer acceptor with low energy loss and efficient charge separation2020In: Energy & Environmental Science, ISSN 1754-5692, E-ISSN 1754-5706, Vol. 13, no 12, p. 5017-5027Article in journal (Refereed)
    Abstract [en]

    Obtaining both high open-circuit voltage (V-oc) and short-circuit current density (J(sc)) has been a major challenge for efficient all-polymer solar cells (all-PSCs). Herein, we developed a polymer acceptor PF5-Y5 with excellent optical absorption capability (onset extending to similar to 880 nm and maximum absorption coefficient exceeding 105 cm(-1) in a film), high electron mobility (3.18 x 10(3) cm(2) V-1 s(-1)) and high LUMO level (-3.84 eV) to address such a challenge. As a result, the PBDB-T:PF5-Y5-based all-PSCs achieved a high power conversion efficiency of up to 14.45% with both a high Voc (0.946 V) and a high Jsc (20.65 mA cm(-2)), due to the high and broad absorption coverage, small energy loss (0.57 eV) and efficient charge separation and transport in the device, which are among the best values in the all-PSC field. In addition, the all-PSC shows a similar to 15% improvement in PCE compared to its counterpart small molecule acceptor (Y5)-based device. Our results suggest that PF5-Y5 is a very promising polymer acceptor candidate for applications in efficient all-PSCs.

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  • 40.
    Fan, Qunping
    et al.
    Chalmers Univ Technol, Sweden.
    Ma, Ruijie
    Hong Kong Univ Sci & Technol, Peoples R China; Hong Kong Univ Sci & Technol, Peoples R China.
    Liu, Tao
    Hong Kong Univ Sci & Technol, Peoples R China; Hong Kong Univ Sci & Technol, Peoples R China.
    Yu, Jianwei
    Linköping University, Department of Physics, Chemistry and Biology, Electronic and photonic materials. Linköping University, Faculty of Science & Engineering.
    Xiao, Yiqun
    Chinese Univ Hong Kong, Peoples R China.
    Su, Wenyan
    Chalmers Univ Technol, Sweden; Karlstad Univ, Sweden.
    Cai, Guilong
    Department of Physics, The Chinese University of Hong Kong, New Territories, 999077, Hong Kong, China.
    Li, Yuxiang
    Xian Univ Sci & Technol, Peoples R China.
    Peng, Wenhong
    Chalmers Univ Technol, Sweden.
    Guo, Tao
    Chalmers Univ Technol, Sweden.
    Luo, Zhenghui
    Hong Kong Univ Sci & Technol, Peoples R China; Hong Kong Univ Sci & Technol, Peoples R China.
    Sun, Huiliang
    Hong Kong Univ Sci & Technol, Peoples R China; Hong Kong Univ Sci & Technol, Peoples R China.
    Hou, Lintao
    Jinan Univ, Peoples R China.
    Zhu, Weiguo
    Changzhou Univ, Peoples R China.
    Lu, Xinhui
    Chinese Univ Hong Kong, Peoples R China.
    Gao, Feng
    Linköping University, Department of Physics, Chemistry and Biology, Electronic and photonic materials. Linköping University, Faculty of Science & Engineering.
    Moons, Ellen
    Karlstad Univ, Sweden.
    Yu, Donghong
    Aalborg Univ, Denmark; Sino Danish Ctr Educ & Res, Denmark.
    Yan, He
    Hong Kong Univ Sci & Technol, Peoples R China; Hong Kong Univ Sci & Technol, Peoples R China.
    Wang, Ergang
    Chalmers Univ Technol, Sweden; Zhengzhou Univ, Peoples R China.
    High-performance all-polymer solar cells enabled by a novel low bandgap non-fully conjugated polymer acceptor2021In: Science in China Series B: Chemistry, ISSN 1674-7291, E-ISSN 1869-1870, Vol. 64, no 8, p. 1380-1388Article in journal (Refereed)
    Abstract [en]

    Anon-fully conjugated polymer as a new class of acceptor materials has shown some advantages over its small molecular counterpart when used in photoactive layers for all-polymer solar cells (all-PSCs), despite a low power conversion efficiency (PCE) caused by its narrow absorption spectra. Herein, a novel non-fully conjugated polymer acceptor PFY-2TS with a low bandgap of similar to 1.40 eV was developed, via polymerizing a large pi-fused small molecule acceptor (SMA) building block (namely YBO) with a non-conjugated thioalkyl linkage. Compared with its precursor YBO, PFY-2TS retains a similar low bandgap but a higher LUMO level. Moreover, compared with the structural analog of YBO-based fully conjugated polymer acceptor PFY-DTC, PFY-2TS shows similar absorption spectrum and electron mobility, but significantly different molecular crystallinity and aggregation properties, which results in optimal blend morphology with a polymer donor PBDB-T and better device physical processes in all-PSCs. As a result, PFY-2TS-based all-PSCs achieved a PCE of 12.31% with a small energy loss of 0.56 eV enabled by the reduced non-radiative energy loss (0.24 eV), which is better than that of 11.08% for the PFY-DTC-based ones. Our work clearly demonstrated that non-fully conjugated polymers as a new class of acceptor materials are very promising for the development of high-performance all-PSCs.

  • 41.
    Fan, Qunping
    et al.
    Xi An Jiao Tong Univ, Peoples R China.
    Ma, Ruijie
    Hong Kong Polytech Univ, Peoples R China.
    Yang, Jie
    Beijing Inst Technol, Peoples R China.
    Gao, Jingshun
    Xi An Jiao Tong Univ, Peoples R China; Zhongyuan Univ Technol, Peoples R China.
    Bai, Hairui
    Xi An Jiao Tong Univ, Peoples R China.
    Su, Wenyan
    Xian Univ Sci & Technol, Peoples R China.
    Liang, Zezhou
    Xi An Jiao Tong Univ, Peoples R China.
    Wu, Yue
    Soochow Univ, Peoples R China.
    Tang, Lingxiao
    Xi An Jiao Tong Univ, Peoples R China.
    Li, Yuxiang
    Xian Univ Sci & Technol, Peoples R China.
    Wu, Qiang
    Xi An Jiao Tong Univ, Peoples R China.
    Wang, Kun
    Zhongyuan Univ Technol, Peoples R China.
    Yan, Lihe
    Xi An Jiao Tong Univ, Peoples R China.
    Zhang, Rui
    Linköping University, Department of Physics, Chemistry and Biology, Electronic and photonic materials. Linköping University, Faculty of Science & Engineering.
    Gao, Feng
    Linköping University, Department of Physics, Chemistry and Biology, Electronic and photonic materials. Linköping University, Faculty of Science & Engineering.
    Li, Gang
    Hong Kong Polytech Univ, Peoples R China.
    Ma, Wei
    Xi An Jiao Tong Univ, Peoples R China.
    Unidirectional Sidechain Engineering to Construct Dual-Asymmetric Acceptors for 19.23 % Efficiency Organic Solar Cells with Low Energy Loss and Efficient Charge Transfer2023In: Angewandte Chemie International Edition, ISSN 1433-7851, E-ISSN 1521-3773Article in journal (Refereed)
    Abstract [en]

    Achieving both high open-circuit voltage (V-oc) and short-circuit current density (J(sc)) to boost power-conversion efficiency (PCE) is a major challenge for organic solar cells (OSCs), wherein high energy loss (E-loss) and inefficient charge transfer usually take place. Here, three new Y-series acceptors of mono-asymmetric asy-YC11 and dual-asymmetric bi-asy-YC9 and bi-asy-YC12 are developed. They share the same asymmetric D(1)AD(2) (D-1=thieno[3,2-b]thiophene and D-2=selenopheno[3,2-b]thiophene) fused-core but have different unidirectional sidechain on D-1 side, allowing fine-tuned molecular properties, such as intermolecular interaction, packing pattern, and crystallinity. Among the binary blends, the PM6 : bi-asy-YC12 one has better morphology with appropriate phase separation and higher order packing than the PM6 : asy-YC9 and PM6 : bi-asy-YC11 ones. Therefore, the PM6 : bi-asy-YC12-based OSCs offer a higher PCE of 17.16 % with both high V-oc and J(sc), due to the reduced E-loss and efficient charge transfer properties. Inspired by the high V-oc and strong NIR-absorption, bi-asy-YC12 is introduced into efficient binary PM6 : L8-BO to construct ternary OSCs. Thanks to the broadened absorption, optimized morphology, and furtherly minimized E-loss, the PM6 : L8-BO : bi-asy-YC12-based OSCs achieve a champion PCE of 19.23 %, which is one of the highest efficiencies among these annealing-free devices. Our developed unidirectional sidechain engineering for constructing bi-asymmetric Y-series acceptors provides an approach to boost PCE of OSCs.

  • 42.
    Fan, Xiangyang
    et al.
    Pukyong Natl Univ, South Korea.
    Wang, Yu
    Linköping University, Department of Physics, Chemistry and Biology, Electronic and photonic materials. Linköping University, Faculty of Science & Engineering.
    Shen, Xinyu
    Sungkyunkwan Univ SKKU, South Korea; Univ Oxford, England.
    Yu, Zhongkai
    Sungkyunkwan Univ SKKU, South Korea.
    Jeong, Woo Hyeon
    Sungkyunkwan Univ SKKU, South Korea.
    Jang, Ji Won
    Hanyang Univ, South Korea.
    Kim, Yeong Gyeong
    Pukyong Natl Univ, South Korea.
    Woo, Seung-Je
    Seoul Natl Univ, South Korea.
    Ahn, Hyungju
    POSTECH, South Korea.
    Choi, Hyosung
    Hanyang Univ, South Korea.
    Lee, Tae-Woo
    Seoul Natl Univ, South Korea.
    Park, Sung Heum
    Pukyong Natl Univ, South Korea.
    Gao, Feng
    Linköping University, Department of Physics, Chemistry and Biology, Electronic and photonic materials. Linköping University, Faculty of Science & Engineering.
    Lee, Bo Ram
    Sungkyunkwan Univ SKKU, South Korea.
    Phosphine oxide modulator-ameliorated hole injection for blue perovskite light-emitting diodes2023In: Journal of Materials Chemistry A, ISSN 2050-7488, E-ISSN 2050-7496, Vol. 11, no 38, p. 20808-20815Article in journal (Refereed)
    Abstract [en]

    Despite the enormous developments in perovskite light-emitting diodes (PeLEDs) recently, obtaining efficient blue PeLEDs is still considered a critical challenge due to the non-radiative recombination and unbalanced charge injection caused by the unmatched carrier mobility and the deep hole-injection barrier between the hole-transport layer (HTL) and the emissive layer (EML). Herein, we incorporate tris(4-trifluoromethylphenyl)phosphine oxide (TMFPPO), obtained through a facile oxidation synthesis process, into poly(9-vinylcarbazole) (PVK). TMFPPO incorporation modulated the energy level and hole mobility of the binary-blend HTLs to eliminate the hole-injection barrier and balance the charge injection within the EML. Consequently, the blue PeLEDs with blended HTL presented an external quantum efficiency (EQE) of 7.23% centred at 477 nm, which was much higher than the EQE of a PVK device (4.95%). Our results demonstrate that modulating the energy level and charge injection of the HTL in the device is a promising method for obtaining efficient blue PeLEDs. TMFPPO is developed and incorporated into PVK to modulate the hole mobility and energy level of the hole-transport layer, giving rise to a barrier-free blue perovskite light-emitting diode and an enhancement of the EQE from 4.95 to 7.23% at 477 nm.

  • 43.
    Fang, Tao
    et al.
    Nanjing Univ Sci & Technol, Peoples R China; Inst Optoelect & Nanomat, Peoples R China.
    Wang, Tiantian
    Nanjing Univ Sci & Technol, Peoples R China; Inst Optoelect & Nanomat, Peoples R China.
    Li, Xiansheng
    Nanjing Univ Sci & Technol, Peoples R China; Inst Optoelect & Nanomat, Peoples R China.
    Dong, Yuhui
    Nanjing Univ Sci & Technol, Peoples R China; Inst Optoelect & Nanomat, Peoples R China.
    Bai, Sai
    Linköping University, Department of Physics, Chemistry and Biology, Electronic and photonic materials. Linköping University, Faculty of Science & Engineering.
    Song, Jizhong
    Nanjing Univ Sci & Technol, Peoples R China; Inst Optoelect & Nanomat, Peoples R China.
    Perovskite QLED with an external quantum efficiency of over 21% by modulating electronic transport2021In: Science Bulletin, ISSN 2095-9273, Vol. 66, no 1, p. 36-43Article in journal (Refereed)
    Abstract [en]

    Perovskite quantum-dot-based light-emitting diodes (QLEDs) are highly promising for future solid-state lightings and high-definition displays due to their excellent color purity. However, their device performance is easily affected by charge accumulation induced luminescence quenching due to imbalanced charge injection in the devices. Here we report green perovskite QLEDs with simultaneously improved efficiency and operational lifetime through balancing the charge injection with the employment of a bilayered electron transport structure. The charge-balanced QLEDs exhibit a color-saturated green emission with a full-width at half-maximum (FWHM) of 18 nm and a peak at 520 nm, a low turn-on voltage of 2.0 V and a champion external quantum efficiency (EQE) of 21.63%, representing one of the most efficient perovskite QLEDs so far. In addition, the devices with modulated charge balance demonstrate a nearly 20-fold improvement in the operational lifetime compared to the control device. Our results demonstrate the great potential of further improving the device performance of perovskite QLEDs toward practical applications in lightings and displays via rational device engineering. (C) 2020 Science China Press. Published by Elsevier B.V. and Science China Press. All rights reserved.

  • 44.
    Fernandez-Benito, Amparo
    et al.
    CSIC, Spain.
    Martinez-Lopez, Juan Carlos
    CSIC, Spain.
    Jafari, Mohammad Javad
    Linköping University, Department of Physics, Chemistry and Biology, Biophysics and bioengineering. Linköping University, Faculty of Science & Engineering.
    Solin, Niclas
    Linköping University, Department of Physics, Chemistry and Biology, Electronic and photonic materials. Linköping University, Faculty of Science & Engineering.
    Martinez Gil, Jose Gabriel
    Linköping University, Department of Physics, Chemistry and Biology, Sensor and Actuator Systems. Linköping University, Faculty of Science & Engineering.
    Garcia-Gimenez, Daniel
    CSIC, Spain.
    Ederth, Thomas
    Linköping University, Department of Physics, Chemistry and Biology, Biophysics and bioengineering. Linköping University, Faculty of Science & Engineering.
    Inganäs, Olle
    Linköping University, Department of Physics, Chemistry and Biology, Electronic and photonic materials. Linköping University, Faculty of Medicine and Health Sciences.
    Carretero-Gonzalez, Javier
    CSIC, Spain.
    Green and Scalable Biopolymer-Based Aqueous Polyelectrolyte Complexes for Zinc-Ion Charge Storage Devices2023In: ChemElectroChem, E-ISSN 2196-0216Article in journal (Refereed)
    Abstract [en]

    Green and scalable materials are essential to fulfill the need of electrification for transitioning into a fossil-fuels free society, and sustainability is a requirement for all new technologies. Rechargeable batteries are one of the most important elements for electrification, enabling the transition to mobile electronics, electrical vehicles and grid storage. We here report synthesis and characterization of polyelectrolyte complexes of alginate and chitosan, both biopolymers deriving from the sea, for transport of zinc ions in hydrogel electrolytes. We have used vibrational spectroscopy, thermal measurements and microscopy, as well as transport measurements with ohmic or blocking contacts. The transference number for zinc ions is close to 1, the conductivity is approximate to 10 mS/cm, with stability at Zn interfaces seen through 7000 cycles in symmetric zinc//zinc cell. A zinc ion aqueous electrolyte was prepared from blends of chitosan and alginate, by using a simple and scalable route. These green zinc ion electrolytes exhibit a stability window up to 2 V, a zinc ion transference number close to 1, and electrochemical cyclability over 7000 cycles at interfaces to zinc. This biologically derived polyelectrolyte complex offers many possibilities for optimizing transport and stability at electrode interfaces.image

  • 45.
    Fu, Huiting
    et al.
    City Univ Hong Kong, Peoples R China.
    Li, Yuxiang
    City Univ Hong Kong, Peoples R China; Xian Univ Sci & Technol, Peoples R China.
    Yu, Jianwei
    Linköping University, Department of Physics, Chemistry and Biology, Electronic and photonic materials. Linköping University, Faculty of Science & Engineering.
    Wu, Ziang
    Korea Univ, South Korea.
    Fan, Qunping
    City Univ Hong Kong, Peoples R China.
    Lin, Francis
    City Univ Hong Kong, Peoples R China.
    Woo, Han Young
    Korea Univ, South Korea.
    Gao, Feng
    Linköping University, Department of Physics, Chemistry and Biology, Electronic and photonic materials. Linköping University, Faculty of Science & Engineering.
    Zhu, Zonglong
    City Univ Hong Kong, Peoples R China.
    Jen, Alex K-Y
    City Univ Hong Kong, Peoples R China; City Univ Hong Kong, Peoples R China; Univ Washington, WA 98195 USA.
    High Efficiency (15.8%) All-Polymer Solar Cells Enabled by a Regioregular Narrow Bandgap Polymer Acceptor2021In: Journal of the American Chemical Society, ISSN 0002-7863, E-ISSN 1520-5126, Vol. 143, no 7, p. 2665-2670Article in journal (Refereed)
    Abstract [en]

    Y Despite the significant progresses made in all-polymer solar cells (all-PSCs) recently, the relatively low short-circuit current density (J(sc)) and large energy loss are still quite difficult to overcome for further development. To address these challenges, we developed a new class of narrow-bandgap polymer acceptors incorporating a benzotriazole (BTz)-core fused-ring segment, named the PZT series. Compared to the commonly used benzothiadiazole (BT)-containing polymer PYT, the less electron-deficient BTz renders PZT derivatives with significantly red-shifted optical absorption and up-shifted energy levels, leading to simultaneously improved J(sc) and open-circuit voltage in the resultant all-PSCs. More importantly, a regioregular PZT (PZT-gamma) has been developed to achieve higher regiospecificity for avoiding the formation of isomers during polymerization. Benefiting from the more extended absorption, better backbone ordering, and more optimal blend morphology with donor component, PZT-gamma-based all-PSCs exhibit a record-high power conversion efficiency of 15.8% with a greatly enhanced J(sc) of 24.7 mA/cm(2) and a low energy loss of 0.51 eV.

  • 46.
    Gao, Feng
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Electronic and photonic materials. Linköping University, Faculty of Science & Engineering.
    Reichmanis, Elsa
    Lehigh Univ, PA USA.
    Introduction: Emerging Materials for Optoelectronics2023In: Chemical Reviews, ISSN 0009-2665, E-ISSN 1520-6890, Vol. 123, no 18, p. 10835-10837Article in journal (Other academic)
  • 47.
    Gao, Zhi-Wen
    et al.
    Univ Hong Kong, Peoples R China.
    Wang, Yong
    Linköping University, Department of Physics, Chemistry and Biology, Electronic and photonic materials. Linköping University, Faculty of Science & Engineering. Univ Hong Kong, Peoples R China.
    Choy, Wallace C. H.
    Univ Hong Kong, Peoples R China.
    Buried Interface Modification in Perovskite Solar Cells: A Materials Perspective2022In: Advanced Energy Materials, ISSN 1614-6832, E-ISSN 1614-6840, Vol. 12, no 20, article id 2104030Article, review/survey (Refereed)
    Abstract [en]

    Organic-inorganic hybrid perovskite solar cells (PSCs) are promising third-generation solar cells. They exhibit high power conversion efficiency (PCE) and, in theory, can be manufactured with less energy than several more established photovoltaic technologies, particularly solution-processed PSCs. Various materials have been widely utilized to modify the buried bottom interface to improve the performance and long-term stability of PSCs. Here, the latest progress in modifying the buried interface to enhance the performance and stability of PSCs is examined from a materials standpoint, which is classified into inorganic salts, the organic molecular and polymer, carbon materials, perovskite-related materials, and 2D materials. This material perspective is useful in determining the tactics for achieving the theoretical PCE value of PSCs. It also serves as a solid reference of interface adjustment for other layered structure heterojunction devices.

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  • 48.
    Gao, Zhi-Wen
    et al.
    Univ Hong Kong, Peoples R China.
    Wang, Yong
    Linköping University, Department of Physics, Chemistry and Biology, Electronic and photonic materials. Linköping University, Faculty of Science & Engineering.
    Jiang, Zhengyan
    Univ Hong Kong, Peoples R China; Southern Univ Sci & Technol, Peoples R China; Southern Univ Sci & Technol, Peoples R China.
    Hu, Bihua
    Southern Univ Sci & Technol, Peoples R China; Southern Univ Sci & Technol, Peoples R China.
    Xu, Baomin
    Southern Univ Sci & Technol, Peoples R China; Southern Univ Sci & Technol, Peoples R China.
    Choy, Wallace C. H.
    Univ Hong Kong, Peoples R China.
    Multifunctional Ion-Lock Interface Layer Achieved by Solid-Solid Contact Approach for Stabilizing Perovskite Solar Cells2022In: Advanced Functional Materials, ISSN 1616-301X, E-ISSN 1616-3028, Vol. 32, no 26, article id 2200473Article in journal (Refereed)
    Abstract [en]

    It has been a hindering issue in perovskite solar cells that the interfaces between the perovskite and charge transport layers show significantly high concentrations of defects with an amount about 100 times more than inside the bulk perovskite layer. The issue causes substantial reduction in both the efficiency and stability of the devices. Herein, a solid-solid contact approach is demonstrated to realize a multifunctional ion-lock layer with strong chemical interaction to the perovskite layer. The multifunctional ion-lock layer remarkably suppresses the interface defects and tunes the work function, contributing to promoting the carrier extraction, increasing the open-circuit voltage, and enlarging the photocurrent. In addition, the multifunctional ion-lock layer successfully locks ions from movement and thus improves the stability of the devices. Finally, with a multifunctional ion-lock layer, the perovskite solar cells deliver an efficiency of up to 23.13% along with desirable long-term operational, storage, and humidity stability. Consequently, the work offers guidelines for establishing defect-suppressed interfaces between perovskites and hole transport layers.

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  • 49.
    Gillett, Alexander J.
    et al.
    Univ Cambridge, England.
    Privitera, Alberto
    Univ Oxford, England.
    Dilmurat, Rishat
    Univ Mons, Belgium.
    Karki, Akchheta
    Univ Calif Santa Barbara, CA 93106 USA.
    Qian, Deping
    Linköping University, Department of Physics, Chemistry and Biology, Electronic and photonic materials. Linköping University, Faculty of Science & Engineering.
    Pershin, Anton
    Univ Mons, Belgium; Wigner Res Ctr Phys, Hungary.
    Londi, Giacomo
    Univ Mons, Belgium.
    Myers, William K.
    Univ Oxford, England.
    Lee, Jaewon
    Univ Calif Santa Barbara, CA 93106 USA; Chungnam Natl Univ, South Korea.
    Yuan, Jun
    Linköping University, Department of Physics, Chemistry and Biology, Electronic and photonic materials. Linköping University, Faculty of Science & Engineering. Cent South Univ, Peoples R China.
    Ko, Seo-Jin
    Univ Calif Santa Barbara, CA 93106 USA; Korea Res Inst Chem Technol, South Korea.
    Riede, Moritz K.
    Univ Oxford, England.
    Gao, Feng
    Linköping University, Department of Physics, Chemistry and Biology, Electronic and photonic materials. Linköping University, Faculty of Science & Engineering.
    Bazan, Guillermo C.
    Univ Calif Santa Barbara, CA 93106 USA.
    Rao, Akshay
    Univ Cambridge, England.
    Nguyen, Thuc-Quyen
    Univ Calif Santa Barbara, CA 93106 USA.
    Beljonne, David
    Univ Mons, Belgium.
    Friend, Richard H.
    Univ Cambridge, England.
    The role of charge recombination to triplet excitons in organic solar cells2021In: Nature, ISSN 0028-0836, E-ISSN 1476-4687, Vol. 597, no 7878, p. 666-+Article in journal (Refereed)
    Abstract [en]

    The use of non-fullerene acceptors (NFAs) in organic solar cells has led to power conversion efficiencies as high as 18%(1). However, organic solar cells are still less efficient than inorganic solar cells, which typically have power conversion efficiencies of more than 20%(2). A key reason for this difference is that organic solar cells have low open-circuit voltages relative to their optical bandgaps(3), owing to non-radiative recombination(4). For organic solar cells to compete with inorganic solar cells in terms of efficiency, non-radiative loss pathways must be identified and suppressed. Here we show that in most organic solar cells that use NFAs, the majority of charge recombination under open-circuit conditions proceeds via the formation of non-emissive NFA triplet excitons; in the benchmark PM6:Y6 blend(5), this fraction reaches 90%, reducing the open-circuit voltage by 60 mV. We prevent recombination via this non-radiative channel by engineering substantial hybridization between the NFA triplet excitons and the spin-triplet charge-transfer excitons. Modelling suggests that the rate of back charge transfer from spin-triplet charge-transfer excitons to molecular triplet excitons may be reduced by an order of magnitude, enabling re-dissociation of the spin-triplet charge-transfer exciton. We demonstrate NFA systems in which the formation of triplet excitons is suppressed. This work thus provides a design pathway for organic solar cells with power conversion efficiencies of 20% or more. A substantial pathway for energy loss in organic solar cells may be suppressed by engineering hybridization between non-fullerene acceptor triplet excitons and spin-triplet charge transfer excitons.

  • 50.
    Gillett, Alexander J.
    et al.
    Univ Cambridge, England.
    Tonnele, Claire
    Donostia Int Phys Ctr DIPC, Spain.
    Londi, Giacomo
    Univ Mons, Belgium.
    Ricci, Gaetano
    Univ Namur, Belgium; Univ Namur, Belgium.
    Catherin, Manon
    Aix Marseille Univ, France.
    Unson, Darcy M. L.
    Univ Cambridge, England.
    Casanova, David
    Donostia Int Phys Ctr DIPC, Spain.
    Castet, Frederic
    Univ Bordeaux, France.
    Olivier, Yoann
    Univ Namur, Belgium; Univ Namur, Belgium.
    Chen, Weimin
    Linköping University, Department of Physics, Chemistry and Biology, Electronic and photonic materials. Linköping University, Faculty of Science & Engineering.
    Zaborova, Elena
    Aix Marseille Univ, France.
    Evans, Emrys W.
    Univ Cambridge, England; Swansea Univ, Wales.
    Drummond, Bluebell H.
    Univ Cambridge, England.
    Conaghan, Patrick J.
    Univ Cambridge, England; Univ Sydney, Australia.
    Cui, Lin-Song
    Univ Cambridge, England; Univ Sci & Technol China, Peoples R China.
    Greenham, Neil C.
    Univ Cambridge, England.
    Puttisong, Yuttapoom
    Linköping University, Department of Physics, Chemistry and Biology, Electronic and photonic materials. Linköping University, Faculty of Science & Engineering.
    Fages, Frederic
    Aix Marseille Univ, France.
    Beljonne, David
    Univ Mons, Belgium.
    Friend, Richard H.
    Univ Cambridge, England.
    Spontaneous exciton dissociation enables spin state interconversion in delayed fluorescence organic semiconductors2021In: Nature Communications, E-ISSN 2041-1723, Vol. 12, no 1, article id 6640Article in journal (Refereed)
    Abstract [en]

    Engineering a low singlet-triplet energy gap (Delta E-ST) is necessary for efficient reverse intersystem crossing (rISC) in delayed fluorescence (DF) organic semiconductors but results in a small radiative rate that limits performance in LEDs. Here, we study a model DF material, BF2, that exhibits a strong optical absorption (absorption coefficient = 3.8 x 10(5) cm(-1)) and a relatively large Delta E-ST of 0.2 eV. In isolated BF2 molecules, intramolecular rISC is slow (delayed lifetime = 260 mu s), but in aggregated films, BF2 generates intermolecular charge transfer (inter-CT) states on picosecond timescales. In contrast to the microsecond intramolecular rISC that is promoted by spin-orbit interactions in most isolated DF molecules, photoluminescence-detected magnetic resonance shows that these inter-CT states undergo rISC mediated by hyperfine interactions on a similar to 24 ns timescale and have an average electron-hole separation of &gt;= 1.5 nm. Transfer back to the emissive singlet exciton then enables efficient DF and LED operation. Thus, access to these inter-CT states, which is possible even at low BF2 doping concentrations of 4 wt%, resolves the conflicting requirements of fast radiative emission and low Delta E-ST in organic DF emitters.

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