Improved Average Figure-of-Merit of High-Efficiency Non-Fullerene Solar Cells via Minor Combinatory Side Chain Approach

摘要： The cost-effectiveness for polymer solar cells is a very important concern for future application. In this work, a new combinatory side chain integrating siloxane terminal and alkoxy group is developed and three polymers PQSi05, PQSi10 and PQSi25 with 5%, 10%, and 25% contents of the siloxane-terminated alkoxy side chain, respectively, are successfully synthesized. As the content of the combinatory side chain increases, the surface energy of the corresponding polymer film would be decreased, showing tunable miscibility in blend films with non-fullerene acceptor IT-4F. Maximum power conversion efficiency (PCE) of 13.56% is achieved in PQSi05:IT-4F based device. The minor (5%) combinatory side chain approach can retain a low synthetic complexity (SC) of 16.58% for PQSi05. Due to the improved device performance, a low figure-of-merit (FOM) of 1.22 can be obtained for the PQSi05:IT-4F blend. Furthermore, the contribution of the IT-4F acceptor is considered for a comprehensive analysis, giving an average SC (ASC) of 39.31% and an average FOM (AFOM) of 2.90. After statistical analysis and calculation, the PQSi05:IT-4F is the best cost-effective active layer to date. Our findings reveal that the introduction of minor combinatory side chain would be a promising strategy to develop high-performing and cost-effective polymer donors.