Organic photovoltaic effects using CuPc and C60 depending on layer thickness

We have studied photovoltaic effects in ITO/CuPc/Al and ITO/CuPc/C60/BCP/Al devices to investigate the effect of layer thickness of CuPc, C60, 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/C60 heterojunction devices, higher power conversion efficiency was obtained for ITO/20 nm CuPc/40 nm C60/Al, which has a thickness ratio (CuPc:C60) 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.