Front interface defect signature and benefits of CdSeTe thickness and band gap in CdSeTe/CdTe graded solar cell

Abstract

Abstract Thin film solar cells based on CdTe absorber suffer from abnormal current density – voltage (J-V) shapes and opencircuit voltage deficit due to suboptimum device architecture, non-optimal back contact and bulk absorber limiting factors, such as low doping density, grain boundary and low carrier lifetime. In this study, we investigate the role of window/absorber interface defects properties in the JV curve shape and the combined effect of CdSexTe1−x thickness and band gap on the device performance using SCAPS-1D. For donor-type interface defects no abnormalities are reported in the J-V curve shape of the device. Acceptor-like defects show strong effect on the J-V shape and two types of anomalies in the J-V curve are reported, hysteresis and s-kink. Those abnormalities are eliminated when the defects concentration at the front interface is bellow or equal to 1011cm-2. The simulations also point out the optimum CdSeTe thickness and band gap to achieve simultaneously high values of open-circuit voltage and short-circuit density, as well as, high conversion efficiency and fill factor. We demonstrate that further device structural optimization is required in MZO/CdSeTe/CdTe solar cell.