Designing enhanced two-terminal tandem photovoltaic devices with AgSb₂(S_xSe_1−x)₃ absorbers

Integrating silver (Ag) into antimony sulfide selenide Sb(S_xSe_1−x)₃ thin films has recently highlighted their potential as efficient light-absorbing layers in thin-film solar cells. In this work, we have designed and analyzed two-terminal monolithic tandem solar cells with AgSb(S_xSe_1−x)₃ and Sb₂S₃. The novel tandem device is configured with a AgSb(S_xSe_1−x)₃ bottom subcell with and a top subcell with a Sb₂Se₃ photovoltaic device with different bandgaps, enabling the selective absorption of targeted photon energy. The upper absorber layer's thickness is carefully calibrated according to the sulfur concentration optimized at x_sulfur = 0.2 of the AgSb(S_xSe_1−x)₃ layer to enhance the performance. The bandgap energies for the AgSb(S_0.2Se_0.8)₃ bottom and the Sb₂Se₃ top subcells are optimized at 1.19 eV and 1.7 eV, respectively. After employing spectral filtering and current matching methodologies, tandem devices demonstrate open-circuit voltage (Voc) of 1.63 V, short-circuit current density (Jsc) of 17.04 mA/cm², and fill factor (FF) of 62.94 %. These tandem devices could be promising candidates for future photovoltaic devices. The power conversion efficiency is 17.48 %, which shows a promising candidate for high-performing tandem solar cells.