Organic photovoltaic effects using CuPc and C 60 depending on layer thickness

Abstract

We have studied photovoltaic effects in ITO/CuPc/Al and ITO/CuPc/C 60/BCP/Al devices to investigate the effect of layer thickness of CuPc, C 60, and BCP exciton blocking layer. The thickness of CuPc single layer was varied from 10 nm to 50 nm using thermal vapor deposition, and we obtained optimum current density-voltage characteristics of ITO/CuPc/Al for 40 nm thick CuPc layer. From the thickness-dependent photovoltaic effects in CuPc/C 60 heterojunction devices, higher power conversion efficiency was obtained for ITO/20 nm CuPc/40 nm C 60/Al, which has a thickness ratio (CuPc:C 60) of 1:2. The BCP layer was introduced as an exciton blocking layer, and there was a pronounced improvement of conversion efficiency with the use of BCP layer.