Design prospect of CdTe solar cell using NW-CdS window layer and 3D graphene as back electrode from numerical approach

In this work, a new cadmium telluride (CdTe) photovoltaic structure has been developed to achieve a high-power conversion efficiency (η) at low cost for thin film photovoltaic. The blue spectrum is surprisingly restricted by the cadmium sulfide (CdS) window layer in the CdTe solar cell. Thus, to improve the shorter wavelength collections, we have replaced the planar CdS layer with nanowire CdS (NW-CdS) window layer. With this change, the quantum efficiency has significantly improved in a shorter wavelength range and the photocurrent has increased by more than 27% compared to the planar CdS device structure. Furthermore, a good back contact material with lower contact resistivity is also important to achieve maximum power conversion efficiency. To obtain an Ohmic, low-resistance contact, a 3D graphene layer has been used as a back contact. Using the SCAPS-1D simulation software, the newly proposed CdTe solar cell’s photovoltaic characteristics were thoroughly investigated. Our calibrated simulation results show that the suggested NW-CdS with graphene solar cell structure produce higher photocurrent density (J_SC) and fill factor (FF). The power conversion efficiency (η) was found to be 14.58%, comparatively higher than the baseline CdTe solar cell efficiency (η = 9.04%).