Valence electronic structure at the interface of organic thin films

Abstract

Valence electronic levels at the interfaces of a photovoltaic double-layered organic thin film, fabricated from N,N′-dimethylperylene-3,4, 9,10-bis(dicarboximide) (DM-PBDCI) as an n-type semiconductor and aluminum phthalocyanine chloride (AlPcCl) as a p-type one, have been examined by UPS employing a spherical-retarding field electron analyzer, and, in particular, thickness dependences of the photoelectron spectra of single- and double-layered films have studied in detail. The electronic structure of a DM-PBDCI film at the interface with a ZnO substrate shows a different behavior from that with a Cu one. An energetic scheme for the interface of an AlPcCl/DM-PBDCI film is proposed on the basis of the obtained results, and it could be considered to be consistent with a conclusion from the theory of p-n heterojunction.