Achieving high performance organic solar cells with a closer π-π distance in branched alkyl-chain acceptors

• Published in: Journal of materials chemistry. A, Materials for energy and sustainability Vol. 11; no. 17; pp. 9538 - 9545
• Main Authors: Tan, Pu, Cao, Congcong, Cheng, Yue, Chen, Hui, Lai, Hanjian, Zhu, Yulin, Han, Liang, Qu, Jianfei, Zheng, Nan, Zhang, Yuanzhu, He, Feng
• Format: Journal Article
• Language: English
• Published: Cambridge Royal Society of Chemistry 02.05.2023
• Subjects: Chain branching; Configurations; Energy conversion efficiency; Functional groups; Optimization; Photovoltaic cells; Photovoltaics; Polymers; Solar cells
• ISSN: 2050-7488; 2050-7496
• DOI: 10.1039/d3ta01049j

Side-chain functional groups have been shown to not only ensure solubility but also influence molecular packing behavior, and side-chain modification is an important strategy in the optimization of photovoltaic performance. Instead of focusing on the size of the alkyl side chains, we have investigated the influence of side-chain configurations on the properties of acceptors and organic solar cells (OSCs). Two acceptor molecules, BTIC-TCl- b and BTIC-TCl- l were designed by changing the linear configuration of alkyl chain substituents on thiophene rings to a branched structure. The results show that the branched configuration of the side-chain can significantly improve the planarity and reduce the π π distances, leading to a more compact 3D-network structure. With the polymer donor PBDB-TF, an outstanding power conversion efficiency (PCE) of 16.17% was achieved by BTIC-TCl- b , which is significantly higher than that found with BTIC-TCl- l . Our study offers new insights for side-chain modification, regulation of the aggregation state, and optimization of photovoltaic performance. This study describes a strategy for improving organic photovoltaic materials performance by adjusting the packing mode with a branched alkyl-chain, BTIC-TCl- b . This modification significantly reduces the π-π distance and boosts the power conversion efficiency up to 16.71%.