Analyzing photo-induced interfacial charging in IZO/pentacene/C60/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/C60 and C60/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 C60 layers, which significantly suppresses the charge accumulation on the pentacene/C60 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.