Benzo[c][1,2,5]thiadiazole doubly fused with thieno[2',3':4,5]thieno[3,2-b]pyrroles as a key building block for non-fullerene acceptors of Y6 series

Organic solar cells have attracted much attention nowadays due to their great advantages such as lightweight, mechanical flexibility, semitransparency, and indoor applicability as next generation renewable energy devices. The most promising types of organic solar cells at the moment are cells with a bulk heterojunction, in which the key components are non-fullerene acceptors. The title building block, more strictly named as 12,13-dihydro[1,2,5]thiadiazolo[3,4-e]thieno[2'',3'':4',5']thieno[2',3':4,5]pyrrolo[3,2-g] thieno[2',3':4,5]thieno[3,2-b]indole, is most commonly used in the design of non-fullerene acceptors in organic bulk heterojunction solar cells. This review presents data on the synthesis of this polycycle and its transformations into organic functional materials including components of highly efficient solar cells.