On the role of asymmetric molecular geometry in high-performance organic solar cells

Jinfeng Huang; Tianyi Chen; Le Mei; Mengting Wang; Yuxuan Zhu; Jiting Cui; Yanni Ouyang; Youwen Pan; Zhaozhao Bi; Wei Ma; Zaifei Ma; Haiming Zhu; Chunfeng Zhang; Xian-Kai Chen; Hongzheng Chen; Lijian Zuo

doi:10.1038/s41467-024-47707-5

On the role of asymmetric molecular geometry in high-performance organic solar cells

Nat Commun. 2024 Apr 16;15(1):3287. doi: 10.1038/s41467-024-47707-5.

Authors

Jinfeng Huang^#^{1

2}, Tianyi Chen^#¹, Le Mei^#^{3

4}, Mengting Wang^#¹, Yuxuan Zhu⁵, Jiting Cui⁶, Yanni Ouyang⁷, Youwen Pan¹, Zhaozhao Bi⁸, Wei Ma⁸, Zaifei Ma⁵, Haiming Zhu⁶, Chunfeng Zhang⁷, Xian-Kai Chen^{9

10}, Hongzheng Chen¹¹, Lijian Zuo^{12

13}

Affiliations

¹ State Key Laboratory of Silicon and Advanced Semiconductor Materials, Department of Polymer Science and Engineering, Zhejiang University, Hangzhou, 310027, PR China.
² Zhejiang University-Hangzhou Global Scientific and Technological Innovation Center, Hangzhou, 310014, PR China.
³ Department of Chemistry, City University of Hong Kong, Kowloon, 999077, Hong Kong.
⁴ Institute of Functional Nano & Soft Materials (FUNSOM), Soochow University, Suzhou, 215123, Jiangsu, PR China.
⁵ State Key Laboratory for Modification of Chemical Fibers and Polymer Materials, Center for Advanced Low-dimension Materials, College of Materials Science and Engineering, Donghua University, Shanghai, 201620, China.
⁶ State Key Laboratory of Modern Optical Instrumentation, Key Laboratory of Excited-State Materials of Zhejiang Province, Department of Chemistry, Zhejiang University, Hangzhou, Zhejiang, 310027, China.
⁷ National Laboratory of Solid State Microstructures, School of Physics, and Collaborative Innovation Center for Advanced Microstructures, Nanjing University, Nanjing, 210093, China.
⁸ State Key Laboratory for Mechanical Behavior of Materials, Xi'an Jiaotong University, Xi'an Jiaotong University, Xi'an, 710049, PR China.
⁹ Institute of Functional Nano & Soft Materials (FUNSOM), Soochow University, Suzhou, 215123, Jiangsu, PR China. xkchen@suda.edu.cn.
¹⁰ Jiangsu Key Laboratory of Advanced Negative Carbon Technologies, Soochow University, Suzhou, 215123, Jiangsu, PR China. xkchen@suda.edu.cn.
¹¹ State Key Laboratory of Silicon and Advanced Semiconductor Materials, Department of Polymer Science and Engineering, Zhejiang University, Hangzhou, 310027, PR China. hzchen@zju.edu.cn.
¹² State Key Laboratory of Silicon and Advanced Semiconductor Materials, Department of Polymer Science and Engineering, Zhejiang University, Hangzhou, 310027, PR China. zjuzlj@zju.edu.cn.
¹³ Zhejiang University-Hangzhou Global Scientific and Technological Innovation Center, Hangzhou, 310014, PR China. zjuzlj@zju.edu.cn.

^# Contributed equally.

Abstract

Although asymmetric molecular design has been widely demonstrated effective for organic photovoltaics (OPVs), the correlation between asymmetric molecular geometry and their optoelectronic properties is still unclear. To access this issue, we have designed and synthesized several symmetric-asymmetric non-fullerene acceptors (NFAs) pairs with identical physical and optoelectronic properties. Interestingly, we found that the asymmetric NFAs universally exhibited increased open-circuit voltage compared to their symmetric counterparts, due to the reduced non-radiative charge recombination. From our molecular-dynamic simulations, the asymmetric NFA naturally exhibits more diverse molecular interaction patterns at the donor (D):acceptor (A) interface as compared to the symmetric ones, as well as higher D:A interfacial charge-transfer state energy. Moreover, it is observed that the asymmetric structure can effectively suppress triplet state formation. These advantages enable a best efficiency of 18.80%, which is one of the champion results among binary OPVs. Therefore, this work unambiguously demonstrates the unique advantage of asymmetric molecular geometry, unveils the underlying mechanism, and highlights the manipulation of D:A interface as an important consideration for future molecular design.

Abstract

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