Design Rules of the Mixing Phase and Impacts on Device Performance in High-Efficiency Organic Photovoltaics

Journal Article · 26 July 2022 · Research

DOI: https://doi.org/10.34133/2022/9817267 · OSTI ID:1878434

Song, Jingnan ^[1]; Zhang, Ming ^[1]; Hao, Tianyu ^[1]; Yan, Jun ^[2]; Zhu, Lei ^[1]; Zhou, Guanqing ^[1]; Zeng, Rui ^[1]; Zhong, Wenkai ^[1]; Xu, Jinqiu ^[1]; Zhou, Zichun ^[1]; Xue, Xiaonan ^[1]; Chen, Chun-Chao ^[3]; Tang, Weihua ^[4]; Zhu, Haiming ^[5]; Ma, Zaifei ^[6]; Tang, Zheng ^[6]; Zhang, Yongming ^[7]; Liu, Feng  ^[7]

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1. School of Chemistry and Chemical Engineering, Frontiers Science Center for Transformative Molecules, Center of Hydrogen Science, Shanghai Key Lab of Electrical Insulation &, Thermal Aging, Shanghai Jiao Tong University, Shanghai 200240, China
2. Department of Physics, Imperial College London, London SW7 2AZ, UK
3. School of Materials Science and Engineering, Shanghai Jiao Tong University, Shanghai 200240, China
4. Institute of Flexible Electronics (IFE, Future Technologies), Xiamen University, Xiamen 361005, China
5. Department of Chemistry, Zhejiang University, Hangzhou 310027, China
6. Center for Advanced Low-Dimension Materials, State Key Laboratory for Modification of Chemical Fibers and Polymer Materials, College of Materials Science and Engineering, Donghua University, Shanghai 201620, China
7. School of Chemistry and Chemical Engineering, Frontiers Science Center for Transformative Molecules, Center of Hydrogen Science, Shanghai Key Lab of Electrical Insulation &, Thermal Aging, Shanghai Jiao Tong University, Shanghai 200240, China, State Key Laboratory of Fluorinated Functional Membrane Materials and Dongyue Future Hydrogen Energy Materials Company, Zibo City, Shandong Province 256401, China

In nonfullerene acceptor- (NFA-) based solar cells, the exciton splitting takes place at both domain interface and donor/acceptor mixture, which brings in the state of mixing phase into focus. The energetics and morphology are key parameters dictating the charge generation, diffusion, and recombination. It is revealed that tailoringthe electronic properties of the mixing region by doping with larger-bandgap components could reduce the density of state but elevate the filling state level, leading to improved open-circuit voltage ( $V_{\text{OC}}$ ) and reduced recombination. The monomolecular and bimolecular recombinations are shown to be intercorrelated, which show a Gaussian-like relationship with $V_{\text{OC}}$ and linear relationship with short-circuit current density ( $J_{\text{SC}}$ ) and fill factor (FF). The kinetics of hole transfer and exciton diffusion scale with $J_{\text{SC}}$ similarly, indicating the carrier generation in mixing region and crystalline domain are equally important. From the morphology perspective, the crystalline order could contribute to $V_{\text{OC}}$ improvement, and the fibrillar structure strongly affects the FF. These observations highlight the importance of the mixing region and its connection with crystalline domains and point out the design rules to optimize the mixing phase structure, which is an effective approach to further improve device performance.

• Research Organization: Shanghai Jiao Tong University (China)
• Sponsoring Organization: 2020CXGC010403; Key Research Project of Shandong Province; National Key R&D Program of China; National Natural Science Foundation of China; Natural Science Foundation of Shandong Province; Shanghai Science and Technology Commission; USDOE Office of Science (SC), Basic Energy Sciences (BES)
• Grant/Contract Number: AC02-05CH11231
• OSTI ID: 1878434
• Journal Information: Research, Journal Name: Research Vol. 2022; ISSN 2639-5274
• Publisher: American Association for the Advancement of Science (AAAS)Copyright Statement
• Country of Publication: United States
• Language: English

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