Influence of trap depth on charge transport in inverted bulk heterojunction solar cells employing zno as electron transport layer

Inverted organic solar cells with device structure ITO/ZnO/ poly(3- hexylthiophene) (P3HT):[6,6]-phenyl C61 butyric acid methyl ester (PCBM) /MoO₃/Ag were fabricated employing low temperature solution processed ZnO as electron selective layer. Devices with varying film thickness of ZnO interlayer were investigated. The optimum film thickness was determined from photovoltaic parameters obtained from current-voltage measurements. The type of charge transport process, distribution of trap states and the ohmicity of the contacts in the optimized device were evaluated using the temperature and illumination intensity dependent study. The results demonstrate the effect of trap depth on device performance and its distribution on the stability of contacts.