Performance Optimization and Bandgap Tuning of Ba(Zr_(1-x)Ti_x)S₃ Perovskite Solar Cells Via Titanium Alloying for High-Efficiency Photovoltaic Systems

Recent advancements in photovoltaic technologies have concentrated on lead-free perovskite materials such as BaZrS3, noted for its effective absorption of visible light and environmental stability. Alloying BaZrS3 with titanium (Ti) represents a significant advancement in improving the efficiency of perovskite solar cells. Kesterite materials, including CZTGS, have garnered interest for their effectiveness as both absorbers and hole-transport materials (HTMs), presenting synergistic possibilities in advanced solar cell designs. This study presents a novel solar cell design that integrates Ti alloying into a BaZrS3-based absorber, resulting in the formation of the <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$\mathbf{Ba}(\mathbf{Zr}_{(1-\mathrm{x})}\mathbf{Ti}_{\mathbf{x}})\mathbf{S}_{3}$</tex> compound. The alloying process is examined with <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$\mathbf{x}$</tex> values from <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$\mathbf{0}$</tex> to 0.04, resulting in a bandgap reduction from 1.78 <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$e$</tex>V to 1.51 eV. The optimized device structure, <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$\mathbf{FTO}/\mathbf{TiO}_{2}/\mathbf{Ba}(\mathbf{Zr}_{0.96}\mathbf{Ti}_{0.04})\mathbf{S}_{3}/\mathbf{CZTGS}/\mathbf{Pt}$</tex>, is attained at <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$\mathbf{x}= 0.04$</tex>, which corresponds to a bandgap of 1.51 eV. An analysis of tunable parameters, such as absorber bandgap, thickness, and doping concentration, is conducted in conjunction with an investigation of temperature-dependent performance. The optimized device exhibits notable performance, attaining an open-circuit voltage <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$(\mathrm{V}_{\text{oc}})$</tex> of 1.18 V, a short-circuit current density <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$(\mathbf{J}_{\text{sc}})$</tex> of 27.33 mA/cm2, a power conversion efficiency (PCE) of 28.6%, and a fill factor (FF) of 88.9%. The results highlight the considerable potential of this novel design, facilitating the experimental realization of high-efficiency BaZrS3-based perovskite solar cells (PSC).