Pioneering High‐Performance in Next Generation Hybrid Tin Perovskite Solar Cells: A Novel Dual Absorber Paradigm With GA x (FA‐Cs) 1‐x SnI ₂ Br

Tin‐based halide perovskites have emerged as environmentally benign alternatives to lead‐based counterparts for next‐generation photovoltaics. This study presents the design and optimization of dual‐absorber perovskite solar cells with the architecture ITO/ETL/GA x (FA 0.8 Cs 0.2 ) 1‐x SnI 2 Br/(CsSnI 3 /MASnI 3 /FASnI 3 )/HTL/Au. The proposed structure strategically integrates a wide‐bandgap top absorber with three narrow‐bandgap bottom absorbers to achieve complementary light harvesting and enhanced charge generation and collection. Device simulations using SCAPS‐1D involved systematic optimization of absorber layer thickness, defect densities, interfacial properties, charge transport layers, operating temperature, and back contact work function. The FASnI 3 cell achieved Voc of 1.04 V, Jsc of 29.77 mA/cm 2 , FF of 83.81%, and PCE of 26.05%. For MASnI 3 , Voc was 1.01 V, Jsc 33.59 mA/cm 2 , FF 85.78%, and PCE 29.00%. The CsSnI 3 device delivered the best performance with Voc of 0.99 V, Jsc 34.88 mA/cm 2 , FF 86.00%, and PCE 29.64%. Analyses including Mott–Schottky profiling, recombination mapping, J‐V curves, QE, and capacitance studies provided insights into device physics. TiO 2 emerged as the most suitable electron transport layer due to favorable band alignment, while CuSbS 2 served as an effective hole transport layer. These results highlight the potential of lead‐free, tin‐based dual‐absorber perovskite solar cells as efficient and sustainable candidates for future photovoltaic technologies.