CsSn0.5Ge0.5I3‐Based Lead‐Free Highly Stable Perovskite Solar Cell: Numerical Modeling for Estimating Performance Ceiling

CsSn 0.5 Ge 0.5 I 3 perovskite is reportedly highly stable in ambient open air, lead free, and has excellent optoelectrical properties. An inverted p–i–n solar cell device based on this mixed SnGe perovskite utilizing the reported optical and electrical characteristics of the CsSn 0.5 Ge 0.5 I 3 is simulated. This theoretical device under various recombination regimes to explore the performance ceiling of CsSn 0.5 Ge 0.5 I 3 is put. An optimized configuration of CsSn 0.5 Ge 0.5 I 3 ‐based perovskite solar cell shows an efficiency of 29% under the impact of only intrinsic recombination losses such as radiative (with radiative recombination coefficient of 10 −11 ) and Auger recombination (recombination coefficient of 10 −27 ). When extrinsic factors are considered, such as resistance losses (series resistance as high as 2 Ω cm 2 and shunt resistance as low as 1000 Ω cm 2 ), efficiency decreases to 27.5%. The efficiency is 20% when trap‐assisted Shockley–Read–Hall recombination is considered with voltage loss ( V Loss ) of 0.5 V. Similarly, V Loss = 0.6 V in V OC restricts device efficiency to 15%. Finally, an efficiency waterfall chart summarizes the CsSn 0.5 Ge 0.5 I 3 , efficiency under different extrinsic losses, and the performance loss analysis, providing an optimal design. The results summarized here are expected to be helpful and prompt experimentalists to fabricate this stable lead‐free perovskite solar cell.