A simple organic diode structure with strong rectifying characteristics

A simple organic diode structure has been made based on N,N'-bis(naphthalen-l-yl)-N, N'-bis(phenyl)-benzidine (NPB)/Fullerene (C-60) heterojunction. Ultraviolet photoelectron spectroscopy measurements show an energy level alignment at the heterojunction as such that no potential barrier near this heterojunction to hinder the formation of charge transfer excitons, which recombines at a very fast rate. This fast exciton recombination at this heterojunction makes NPB/C-60 behave like an ideal Ohmic contact and thus leads to an extremely high 7.8 x 10(4) rectifying ratio from the electrode/organic contacts. (C) 2014 Elsevier B.V. All rights reserved.