Photovoltaic properties of CdS/phthalocyanine heterojunction cells

Abstract

Photovoltaic heterojunction solar cells formed between n-type cadmium sulfide, CdS, and various p-type phthaloeyanines (Pc) such as H2Pc, ZnPc, MgPc, CuPc, MnPc, PbPc, and VOPc were investigated. The cells were prepared by electrodepositing thin CdS films onto conducting indium-tin oxide (ITO) followed by sequential vacuum deposition of the phthaloeyanines and gold layers. Among the seven phthaloeyanines studied, ZnPc and MgPc exhibited the highest photovoltaic activity. Some optimization work was done for both the ZnPc and MgPc heterojunction devices. The optimum thickness of CdS and phthaloeyanines was found to be 500 and 850 Å, respectively. Under an illumination of 50 mW cm−2, the photovoltaic characteristics of the ITO/CdS/ZnPc/Au cell were: Voc = 0.54 volts, Jsc = 285 μA cm−2, and η = 0.10%, while the ITO/CdS/MgPc/Au cell delivered Voc = 0.46 volts, Jsc = 231 μA cm−2, and η = 0.066%.