CuPc/C60 solar cells - Influence of the indium tin oxide substrate and device architecture on the solar cell performance

Abstract

We investigated the influence of different indium tin oxide (ITO) surface treatments on the performance of organic solar cells with different device architectures. Two types of devices (CuPc in contact with ITO treated with different treatments and C60 in contact with ITO treated with different treatments) were fabricated. The surfaces of CuPc and C60 layers deposited on ITO substrates treated with different surface treatments were examined using atomic force microscopy. The devices were characterized by measuring current-voltage characteristics in the dark and under AMI illumination. We found that a one order of magnitude improvement in the AMI power conversion efficiency for ITO/CuPc/C60/A1 cells can be achieved for optimal ITO surface treatment, while ITO/C60/CuPc/Cu devices exhibit less sensitivity to surface treatments. Moreover, these devices exhibit better performance compared to ITO/CuPc/C60/Al devices. The observed differences in sensitivity to surface treatments were attributed to difference in the dependence of the film surface on ITO surface morphology for CuPc and C60.