Simulation of light soaking effects in CdTe thin-film solar cells using SCAPS-1D

This study uses SCAPS-1D to investigate the steady-state electrical consequences of experimentally observed light-soaking-induced defect passivation in CdTe solar cells for efficiency improvement through both donor and acceptor defect concentration adjustments. Because SCAPS-1D is a steady-state solver, light soaking is represented here as an approximate quasi-static parametric reduction of defect density (equivalently, an increase in Shockley–Read–Hall, SRH, carrier lifetime), rather than as a direct, time-resolved simulation of ionic migration. Donor defects decreased the open circuit voltage to ~0.8 V due to higher Shockley–Read–Hall recombination, while a decrease in donor concentration increased cell efficiency from 18.22% to 19.45%. Moderate amounts of acceptor defects improve the conductivity of the absorber while higher levels lead to increased recombination. The removal of excess acceptor defects improved cell efficiencies from 15.92% to 20.16% with little effect on the open-circuit voltage. The quantum efficiency results show the same qualitative trend as experimental data, although the simulated post-soaking quantum efficiency plateau near 100% is partly an artifact of the idealized optical and electrical assumptions of the model.