Fine‐Tuning Alkyl Chains on Quinoxaline Nonfullerene Acceptors Enables High‐Efficiency Ternary Organic Solar Cells with Optimizing Molecular Stacking and Reducing Energy Loss

Journal Article · Fri Aug 04 00:00:00 EDT 2023 · Advanced Functional Materials

DOI:https://doi.org/10.1002/adfm.202305611· OSTI ID:1993868

Guo, Yuntong ^[1]; Chen, Zhenyu ^[2]; Ge, Jinfeng ^[2]; Zhu, Jintao ^[3]; Zhang, Jinna ^[2]; Meng, Yuanyuan ^[2]; Ye, Qinrui ^[2]; Wang, Shijie ^[4]; Chen, Fei ^[3]; Ma, Wei ^[4]; Ge, Ziyi  ^[5]

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1. Ningbo Institute of Materials Technology and Engineering Chinese Academy of Sciences Ningbo 315201 China, School of Chemical Engineering Zhejiang University of Technology Hangzhou 310014 China
2. Ningbo Institute of Materials Technology and Engineering Chinese Academy of Sciences Ningbo 315201 China
3. Department of Chemical and Environmental Engineering University of Nottingham Ningbo China Ningbo 315100 China
4. State Key Laboratory for Mechanical Behavior of Materials Xi'an Jiaotong University Xian 710049 China
5. Ningbo Institute of Materials Technology and Engineering Chinese Academy of Sciences Ningbo 315201 China, Zhejiang Engineering Research Center for Energy Optoelectronic Materials and Devices Ningbo 315201 China

Abstract Material design of guest acceptor is always a big challenge for improving the efficiency of ternary organic solar cells (OSCs). Here, a pair of isomeric nonfullerene acceptors based on quinoxaline core, Qx– p ‐C ₇ H ₈ O and Qx– m ‐C ₇ H ₈ O, is designed and synthesized. By moving the alkoxy chain attached on side phenyl from meta ‐position to para ‐position, both π–π stacking distance and crystallinity are enhanced simultaneously. They obtain the uplifted lowest unoccupied molecular orbital level. Compared to Qx– m ‐C ₇ H ₈ O, Qx– p ‐C ₇ H ₈ O exhibits wider absorption spectrum and higher extinction coefficient. Using D18‐Cl:N3 as host materials, the addition of guest acceptor Qx– p ‐C ₇ H ₈ O significantly improves the power conversion efficiency (PCE) from 17.61% to 18.49% because of higher open‐circuit voltage (0.875 V) and short‐circuit current density (27.85 mA cm ⁻² ). This can be attributed to the faster exciton dissociation, more balanced carrier mobility, fine fiber morphology, and lower energy loss in the ternary devices. However, Qx– m ‐C ₇ H ₈ O‐based ternary device achieves relatively low PCE of 17.17% because this device shows extremely low electron mobility. The results indicate that molecular stacking, film morphology, etc., can be effectively modulated by fine‐tuning the side chains of guest materials, which may be an effective design rule for further improving the PCE of OSCs.

• Sponsoring Organization: USDOE
• Grant/Contract Number: DE‐AC02‐05CH11231
• OSTI ID: 1993868
• Journal Information: Advanced Functional Materials, Journal Name: Advanced Functional Materials Vol. 33 Journal Issue: 47; ISSN 1616-301X
• Publisher: Wiley Blackwell (John Wiley & Sons)
• Country of Publication: Germany
• Language: English