Abstract:We demonstrated that N,N′-diphenylperylene tetracarbonic diimide (PTCDI-Ph) could work as an n-type sensitizing layer for the C 60 n-type layer owing to interlayer excitation transfer (ET) when the PTCDI-Ph layer was placed between the C 60 layer and the aluminum anode coupled with the bathocuproine layer. Well-aligned lowest unoccupied molecular orbitals between C 60 and PTCDI-Ph (−4.55 eV for 2 PTCDI-Ph and −4.5 eV for C 60 ) and a larger bandgap for PTCDI-Ph than C 60 (2.04 eV for PTCDI-Ph and 2.0 eV for C 60 ) enabled this interlayer ET-based sensitization. Further, the optical interference effect could be also involved in the sensitization. It was also demonstrated that the combination of both n-type materials C 60 and PTCDI-Ph could successfully reduce the amount of the expensive C 60 used, and a thin C 60 layer was indispensable for efficient charge separation. PTCDI-Ph could work as a light-harvesting n-type material incorporating C 60 -based cells to compensate for C 60 's weak optical absorption.