### 结晶动力学策略在非富勒烯体系太阳能电池形貌调控领域的应用

1. 1 西北工业大学微电子学院, 西安 710072;
2 西北工业大学电子信息学院, 西安 710072
• 收稿日期:2022-12-03 修回日期:2023-01-02 录用日期:2023-01-02
• 通讯作者: 刘剑刚 E-mail:jgliu@nwpu.edu.cn
• 基金资助:
国家自然科学基金(52073231, 51903211, 51773203), 陕西省杰出青年项目(2023-JC-JQ-33), 陕西省高层次人才引进项目(5113220044), 苏州市科协青年科技人才托举工程项目(5111220021), 江苏省科协青年科技人才推举工程项目(TJ-2022-088), 中央高校基础业务费(G2020KY0501, G2021KY05101,G2022KY05108), 西北工业大学青年学者研究基金(G2022WD01014), 重庆市自然科学基金面上项目(cstc2021jcyj-msxmX0990), 太仓市基础研究计划(TC2021JC08), 西北工业大学学位和研究生教育基金(2022AJ12, 2022AJ22)资助

### Application of Crystallization Kinetics Strategy in Morphology Control of Solar Cells Based on Nonfullerene Blends

Qiuju Liang1, Yinxia Chang1, Chaowei Liang1, Haolei Zhu1, Zibin Guo1, Jiangang Liu2

1. 1 School of Microelectronics, Northwestern Polytechnical University, Xi'an 710072, China;
2 School of Electronics and Information, Northwestern Polytechnical University, Xi'an 710072, China
• Received:2022-12-03 Revised:2023-01-02 Accepted:2023-01-02
• Contact: Jiangang Liu E-mail:jgliu@nwpu.edu.cn
• Supported by:
The project was supported by the National Natural Science Foundation of China (52073231, 51903211, 51773203), the Shaanxi Outstanding Youth Project (2023- JC-JQ-33), the Shaanxi Provincial High Level Talent Introduction Project (5113220044), the Youth Talent Promotion of Suzhou Association for Science and Technology (5111220021), the Youth Talent Promotion of Jiangsu Association for Science and Technology (TJ-2022-088), the Fundamental Research Funds for the Central Universities (G2020KY0501, G2021KY05101, G2022KY05108), the NWPU Research Fund for Young Scholars (G2022WD01014), the Natural Science Foundation of Chongqing, China (cstc2021jcyj-msxmX0990), the Basic Research Programs of Taicang (TC2021JC08), the NWPU Degree and Graduate Education Fund (2022AJ12, 2022AJ22).

Abstract: Owing to the advantages of broad absorption, semitransparency, and largearea solution processing, organic solar cells based on a nonfullerene blend system have attracted wide attention and become an important aspect of clean energy. At present, the power conversion efficiency of organic solar cells based on nonfullerene blends is more than 19% because of the molecular design, device structure optimization, and morphology regulation. Organic solar cells consist of a cathode, an anode, the corresponding interface layers, and the active layer. Research shows that the morphology of the active layer has significant influence on the device performance. For example, the phase separation structure affects the charge transport, exciton diffusion efficiency is dependent on the domain sizes of the donor and acceptor, crystallinity has a considerable impact on photon absorption and carrier mobility, and molecular orientation affects the dissociation of the charge-transfer state and carrier mobility. Owing to the rigidity of conjugated molecules, the coupling of crystallization between the donor and acceptor always occurs during the film-forming and/or post-annealing processes. Moreover, crystallization and phase separation are inclined to occur simultaneously, leading to poor morphology control. Although many methods, such as post-annealing, solution-state, solvent or solid additive, and solvent engineering, have been exploited, forming the ideal structure morphology of the active layer is still difficult. This is particularly challenging in nonfullerene blends owing to the asymmetric phase separation behavior. This feature article summarizes the recently developed crystallization kinetics strategy in morphology control, which made precise morphology control possible. In this strategy, the interpenetrating network can be constructed by applying modified film-forming kinetics, which inhibits the liquid–liquid phase separation and induces liquid– solid phase separation. The domain size can be reduced by employing sequential crystallization, where the donor and acceptor crystallize in different stages through the combination of the solution-state and post-annealing treatments, surpassing the driving force of phase separation. In addition, the crystallinity of small nonfullerene molecules in the polymer/nonfullerene blends can be effectively enhanced by prioritizing their crystallization. This shift in crystallization priority can reduce the confinement of crystalline framework polymers and benefit the diffusion of the small nonfullerene molecules. Moreover, the ordered stacking of molecules in crystals can be improved by regulating the matching degree between the crystal nucleation rate and growth rate. Molecular orientation can be regulated by combining the motion scale and heterogeneous nucleation. The optimized morphology is beneficial to device performance as it suppresses exciton quenching, recombination of the charge-transfer state, and bimolecular recombination and improves charge mobility, thereby laying the foundation for high-performance organic solar cells.

MSC2000:

• O649