Optoelectronics Simulation of CIGS-Based Solar Cells Using a Cd-Free Nontoxic ZrSxSe2−x as a Novel Buffer Layer

Abstract

In this work, we investigate the performance of CIGS-based thin-film solar cells employing the SCAPS-1D simulation package. The paper is mainly devoted to the development of the ZrSxSe2−x (where 0 ≤ x ≤ 2) transition metal dichalcogenide (TMDC) as a Cd-free, nontoxic, and abundant buffer layer, the first of its kind. In the first step, we have evaluated the impact of the p-MoSe2 interfacial layer between the GIGS absorber and Mo back contact. The J–V characteristic showed a higher slope, revealing that the p-MoSe2 layer at the CIGS/Mo interfaces beneficially on the CIGS/Mo hetero-contact, mediating the quasi-ohmic contact rather than the Schottky type. For the optimized solar cell using the ZrSxSe2−x as a buffer layer, the photovoltaic parameters, such as the short-circuit current density, open-circuit voltage, Fill Factor, and efficiency, were investigated versus the thickness, carrier concentration, and bandgap values. The results reveal an optimum efficiency of ~ 25.5% at a bandgap of 1.3 eV, corresponding to ZrS0.8Se1.2 (i.e., x = 0.8) and 180 nm thicknesses, at a high carrier concentration of 1 × 1018 cm−3. Furthermore, the solar cell performance is assessed with the increment of the operating temperature from 275 to 475 K. The observed decrease in the Voc is ascribed to the rise in the reverse saturation current associated with the higher temperatures. The study concludes an excellent potential for fabricating high-performance CIGS thin solar cells using a Cd-free nontoxic buffer layer.