High Performance All-Polymer Solar Cells with the Polymer Acceptor Synthesized via a Random Ternary Copolymerization Strategy

All-polymer solar cells (all-PSCs), consisting of polymer donor and polymer acceptor, possess superior intrinsic morphology stability and mechanical flexibility over traditional polymer solar cells (based on polymer donor and small molecule acceptor), which provides viability in the practical commercial applications of organic photovoltaics.

Professor Yongfang Li and colleagues from Institute of Chemistry Chinese Academy of Sciences previously created a novel type of n-type polymer acceptor by polymerizing small molecule acceptor (PSMA) in 2017 (Angew. Chem. Int. Ed. 2017, 56, 13503 –13507). To further improve and perfect the strategy, in the recent published work in Angewandte Chemie (https://doi.org/10.1002/anie.202005357), a way of random ternary copolymerization was introduced into PSMA and a series of polymers named PTPBT-ETx was synthesized. PTPBT-ETxs are copolymerized with small molecule acceptor unit TPBT, thiophene π-bridge unit and the controlled molar ratio of functional 3-ethylesterthiophene (ET) unit (as shown in Figure). Eventually, the champion power conversion efficiency of 12.52% was achieved based on PTPBT-ET0.3.

This methodology holds the advantages that the optical and electrical properties of the PSMAs could be conveniently and controllably optimized by simply tuning the molar ratio of the involved “third” unit. Incorporation of a certain amount of ET moiety into the copolymer backbones not only up-shifts the LUMO level of the polymer acceptor but also enables higher charge-carrier mobility and better morphology for their blend films. In addition, the PTPBT‐ET0.3‐based all-polymer solar cells also exhibits long‐term photostability over 300 hours.

The research was supported by “National Natural Science Foundation of China” and “the Guangdong Major Project of Basic and Applied Basic Research”.

Chemical structure of PTPBT-ETx

Contact:
Prof. Yongfang Li
Institute of Chemistry, Chinese Academy of Sciences
Zhongguancun North First Street 2,100190 Beijing, P. R. China
Tel: 86-10-61943915
E-mail: liyf@iccas.ac.cn