Introducing cyclic alkyl chains into small-molecule acceptors for efficient polymer solar cells

A new acceptor–donor–acceptor type small molecule acceptor, namely IDT-HN, is developed, which consists of a newly developed 2-(3-oxo-2,3,5,6,7,8-hexahydro-1 H -cyclopenta[ b ]naphthalen-1-ylidene)malononitrile as the peripheral electron-withdrawing group.