Interfacial charging of copper phthalocyanine/C60 double-layer organic solar cells induced by photoillumination: Effect of photoconductivity change

Optical electric-field-induced second-harmonic generation measurement was employed for studying interfacial processes in copper phthalocyanine (CuPc)/C60 double-layer organic solar cells. Results suggested that interfacial charging process happened on the CuPc/C60 interface and the applied illumination can change the polarity of the accumulated charges on the double-layer interface while the direction of conduction current is the same. The Maxwell-Wagner model analysis revealed that the photo conductance change is responsible for these converse behaviors with and without illumination.