Optimizing CdTe solar cells with Cd1-xZnxTe absorber layers: DFT and SCAPS-1D simulations of structural, electronic, and optical properties

Cadmium telluride (CdTe) solar cells with Cd₁₋ₓZnₓTe absorbers are an emerging solution in thin-film photovoltaics, combining high efficiency with adaptability. This study integrates density functional theory (DFT) and SCAPS-1D simulations to analyze the structural, electronic, and optical properties of Cd₁₋ₓZnₓTe alloys, addressing challenges in bandgap engineering and material stability. A nonlinear bandgap behaviour with a bowing parameter of (0.49) eV was observed, predominantly due to volume deformation effects. Enhanced photon absorption, effective electron densities, and balanced bandgap tunability were achieved with increased Zn content. Device simulations revealed a peak efficiency of (18.98%), with a short-circuit current density (Jsc) of (25.8 mA/cm 2 ), an open-circuit voltage (Voc) of (1.06 V), and an external quantum efficiency (EQE) of ~ 80% at 350 nm. Loss analysis indicated that optimal Zn composition mitigates recombination losses and enhances photon capture, resulting in a trade-off between improved Voc and stable Jsc values. These findings highlight Cd₁₋ₓZnₓTe as a versatile material for next-generation solar cells, offering significant advancements in efficiency and durability.