A novel design of CTZS/Si tandem solar cell: A numerical approach

Abstract

Abstract Multijunction or tandem solar cells can split the solar spectrum over several subcells with different bandgaps to transform the sunlight into electricity more effectively than single-junction solar cells. The monolithic tandem design of third generation silicon solar energy materials is auspicious for photovoltaics. In this paper, the Simulation-based studies of copper zinc tin sulfide/Silicon (CZTS/Si) tandem cells based on CZTS as an upper subcell and silicon as a lower subcell absorber layer have been performed using SCAPS-1D. This study aims to evaluate the CZTS tandem cells' performance based on the fact that both subcells are simulated to produce the best efficiency recorded at its bandgap. The Simulation and optimization of the single junction CZTS and Si solar cells were initially performed to fit the state-of-art records efficiency of 11.65% and 18.7%, respectively. Further, both the upper and lower cell has evaluated at different thicknesses for tandem configuration after validation. Also, to obtain the current matching condition for tandem structure, the upper subcell's performance is investigated at different thickness ranges from 0.1 µm -1 µm while keeping the lower subcell thickness at 80µm. Thus, at optimized upper absorber thickness of 0.191 µm and lower subcell 80 µm at transmitted spectrum the current matching condition obtained and gave an efficiency of 10.6% and 11.9%, respectively. The maximum efficiency of ~ 23 is obtained for tandem design with enhancing open circuit voltage 1.4 V.