Analyzing photo-induced interfacial charging in IZO/pentacene/C 60/bathocuproine/Al organic solar cells by electric-field-induced optical second-harmonic generation measurement

Abstract

By using electric-field-induced optical second-harmonic generation (EFISHG) measurement, we investigated interfacial carrier behavior in organic solar cells (OSCs) with a blocking layer of bathocuproine (BCP). Results evidently showed that the Maxwell-Wagner type excess charges accumulate on both pentacene/C 60 and C 60/BCP interfaces. Meanwhile, the introduction of BCP layer enhances photocarrier generation in the OSCs and results in the increase of the conductivity of the pentacene and C 60 layers, which significantly suppresses the charge accumulation on the pentacene/C 60 interface. The role of the BCP blocking layer was discussed with taking into account the dielectric nature of the active organic OSC layer on the basis of the Maxwell-Wagner effect model. © 2012 American Institute of Physics.