A hexacyclic ladder-type building block for high-performance D–A copolymers

Abstract

A ladder-type unit thieno[3′,2′:3,4]isoquinolino[8,7-h]thieno[3,2-c]isoquinoline-6,13(7H,14H)-dione (TITI) was invented as an acceptor unit for constructing donor–acceptor (D–A) copolymers. Two polymers PThTITI and PSeTITI were developed by copolymerizing TITI with thiophene (Th) or selenophene (Se). Compared with PThTITI, PSeTITI possesses a lower bandgap and higher hole mobility. PThTITI:PC₇₁BM and PSeTITI:PC₇₁BM solar cells gave power conversion efficiencies (PCEs) of 5.53% and 6.17%, respectively.