The resulting polymers throughcopolymerizing BNTT unit with other electron poor units exhibited excellent electron transfer property. A series of BNTT-basedpolymers (Fig. 7) were synthesized and used as the acceptors inBHJ OSCs [99]. A PCE of 5.04% was obtained for all-PSCs usingP-BN-IID (P20) (Fig. 7) as the acceptor in combination with PTB7–Th.