“…[19,20,[28][29][30][31][32][33][34][35][36][37][38][39][40] To the best of our knowledge, all these high-performance donor polymers are alternating donor-acceptor (D-A) type copolymers, which are exclusively based on benzo[1,2-b:4,5-b′]dithiophene (BDT) donor unit [41] copolymerized with a few acceptor counits, such as 5,6-difluoro-2-alkyl-2H-benzo[d] [1,2,3]triazole (FTAZ), [42] benzo[1,2-c:4,5-c′]-dithiophene-4,8-dione (BDD) [43] etc. [19,20,[28][29][30][31][32][33][34][35][36][37][38][39][40] To the best of our knowledge, all these high-performance donor polymers are alternating donor-acceptor (D-A) type copolymers, which are exclusively based on benzo[1,2-b:4,5-b′]dithiophene (BDT) donor unit [41] copolymerized with a few acceptor counits, such as 5,6-difluoro-2-alkyl-2H-benzo[d] [1,2,3]triazole (FTAZ), [42] benzo[1,2-c:4,5-c′]-dithiophene-4,8-dione (BDD) [43] etc.…”