Polycrystalline CdS/CdTe thin-film solar cells with intrinsic SnO2 films of high resistance

Abstract

Intrinsic SnO2 films as the high resistance transparent (HRT) layers are prepared by ultrasonic spray pyrolysis and used in CdS/CdTe solar cells with a thin CdS layer. XRD and AFM are used to study the performance of the thin CdS layers. The illuminated and dark I-V characteristics, spectral response (SR) and C-V characteristics of the devices are measured. The results show that the thin CdS films deposited on HRT layers have an obvious preferred orientation along (111) plan. But pinholes are formed when using a thin CdS layer. After introducing the HRT layer, the tunneling leakage caused by the pinholes can be avoided, which effectively protects the p-n junction. Meanwhile, higher shunt resistivity, fill factor, short-wave response, carrier concentration and lower dark saturation current density have been achieved. As a result, the conversion efficiency is enhanced by 14.4%.