Constructing D–A copolymers based on thiophene-fused benzotriazole units containing different alkyl side-chains for non-fullerene polymer solar cells

A series of D–A copolymers based on thiophene fused benzotriazole (BTAZT) and 4,8-bis(4-fluorothiophen-2-yl)benzo[1,2-b:4,5-b′]dithiophene (BDTFT) units containing different alkyl side-chains have been constructed as electron-donating materials for non-fullerene PSCs.