Performance assessment of earth-abundant kesterite-based CZTSSe solar cell using graphene oxide as HTL and zinc oxysulfide as ETL

This research investigates the optimization of CZTSSe (copper zinc tin sulfide selenide) solar cells through the integration of graphene oxide (GO) in the role of HTL (hole transport layer) also zinc oxysulfide (Zn(O,S)) in the role of ETL (electron transport layer), replacing the conventional cadmium sulfide (CdS) buffer layer. CZTSSe, characterized by an impactful direct energy bandgap (1–1.5 eV) also a high absorption coefficient (>10⁴ cm⁻¹), exhibits prospects for efficient light absorption in the visible range. The study employs simulation characterization to comprehensively analyze the impact of the GO hole transparent layer and Zn (O,S) buffer layer on the optical and electrical attributes of the CZTSSe photovoltaic(PV) cell. Key parameters, such as power conversion efficiency (PCE), short-circuit current (J_SC), fill factor (FF), and open-circuit voltage (V_OC), are meticulously examined to substantiate the performance of the devices. These parameters include the energy bandgap, variations in thickness, doping concentration, defect density, parasitic resistance, temperature, and generation and recombination processes. The objective is to understand how these factors influence solar cell performances and to enhance light absorption, elevate charge mobility, and minimize carrier recombination losses. The culmination of these efforts results in the CZTSSe solar module achieving its maximum PCE of 28.23% when incorporating a Zn(O,S) ETL along with a GO hole transport layer and ZnO:Al as a window layer.