Abstract Two new perylene diimide molecules, 1, 7-bis (1-naphtyl)-N, N′-bis-(10- nonadecyl)-perylene-3, 4, 9, 10-bis (dicarboximide) PDI-2 and 1, 7-bis (5-acenaphtenyl)-N, N′-bis-(10-nonadecyl)-perylene-3, 4, 9, 10-bis (dicarboximide) PDI-3 have been synthesized and used as acceptor components in P3HT/PDI bulk heterojunction solar cells. The introduction of fused aromatic rings into the bay positions of the perylene core creates ...