Two new perylenediimide 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