Effect and optimization of the Zn3P2 back surface field on the efficiency of CZTS/CZTSSe tandem solar cell: a computational approach

Abstract

Abstract Copper zinc tin sulfide (CZTS) and copper zinc tin sulfo selenide (CZTSSe) kesterite minerals are nontoxic and abundant in the earth with the promise of cost-effective photovoltaic applications. This study explains a tandem solar cell made of kesterite materials that can capture sunlight over a broad spectrum. The proposed tandem structure comprises a wide bandgap CZTS thin-film upper subcell and an underlying narrow bandgap CZTSSe-based lower subcell. The upper and lower subcells are simulated using solar cell capacitance simulator-one dimension and validated against the experimental results to determine the viability of the proposed tandem design. Additionally, the performance of both subcells is evaluated for tandem configuration by adding a back surface field layer, a modification of the back contact, testing at different thicknesses, and doping of both subcell absorber layers. As a result, optimizing both subcells improved tandem solar cell open-circuit voltage (V oc) to a maximum of 1.5 V, which led to an efficiency of 23.99% at the current matching condition. Furthermore, how light radiation power and temperature variations impact the proposed solar cell performance is being investigated. This study provides significant insights into efficient tandem solar cell design and manufacture.