Effect of molecular packing on interfacial recombination of organic solar cells based on palladium phthalocyanine and perylene derivatives

Planar heterojunction solar cells made of three different perylene tetracarboxylic diimide (PTCDI) derivatives as acceptor and palladium phthalocyanine as donor are demonstrated. Electron-hole pair recombination at donor/acceptor interface was compared for three PTCDI derivative solar cells by optical modeling and the effect of molecular packing of the PTCDI derivatives on charge dissociation is discussed. We observed that PTCDI with hexyl chains has the highest charge separation efficiency among three PTCDI derivatives, leading to a power conversion efficiency of 2.0% in solar cells.