Advanced numerical modeling of multi-absorber Cs2AgBiBr6/CsSnCl3 solar cells: unveiling charge dynamics, trap phenomena, and noise characterization of high-efficiency photovoltaics

Abstract

This study presents an extensive numerical modeling of a high-efficiency photovoltaic device featuring a multi-absorber architecture, comprising Cs₂AgBiBr₆ and CsSnCl₃, by exploiting their complementary bandgaps for broader solar spectrum absorption. By optimizing parameters such as absorber thickness, shallow acceptor/donor densities, and trap dynamics—including electron and hole capture cross-sections and energy level distributions—device performance was enhanced. The optimization extended to metal electrode work functions to ensure appropriate band alignment and ohmic contacts. The study further explores the effects of series and parasitic resistances, thermal conditions, and dynamic charge transport transitions, introducing an RC circuit model to include both resistive and capacitive aspects. Electrical profiling and Mott–Schottky analysis revealed shifts in the depletion region and flat band potential conditions, while Johnson–Nyquist noise characterization examined the interplay between noise manifestations and charge carrier dynamics across various device configurations. The final optimized device demonstrated superior performance with V_OC = 1.18 V, J_SC = 20.78 mA cm⁻², FF = 87.14%, and η = 21.75%. This work provides a sophisticated framework for developing efficient, stable photovoltaic devices while offering deeper insights into optoelectronic and semiconductor behavior.