Device Engineering of a New Lead Free All Inorganic CsSnI₃/CsSnCl₃-Based Graded Perovskite Absorber Structure for High Performance Solar Cell

Future developments in perovskite solar cells (PSCs) focuses on lead-free versions because of their lower toxicity. However, lead-free PSCs' limited Power Conversion Efficiency (PCE) compared to their lead-based counterparts prevents them from being used more widely. This issue can be successfully resolved with the multi-absorber approach since it maximizes the use of the solar spectrum. Therefore, this article incorporates numerical modeling guided optimization of a lead free all inorganic ITO/ETL/CsSnI<sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub>/CsSnCl<sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub>/HTL dual absorbers-based heterojunction structure to improve the performance of Cesium Tin Iodide (CsSnI<sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub>) and Cesium Tin Chloride (CsSnCl<sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub>) based single absorber PSCs. The critical device's parameters, such as absorber layer and carrier transport layer thickness, defect density, temperature, doping concentration, series and shunt resistances are thoroughly optimized and evaluated using Solar cell capacitance simulator (SCAPS-1D). The proposed dual absorber composition produces a substantial enhancement in performance with PCE (η) of 24%, Short Circuit Current (<italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">J</i><sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">sc</sub>) of 28.5 mA/cm<sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup>, Open Circuit Voltage (<italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">V</i><sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">oc</sub>) of 0.96 V, and Field Factor (<italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">FF</i>) of 85.87% at a device defect density of 10<sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">15</sup> cm<sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-3</sup> outperforming the 12.96% and 9.66% of PCE attained with the reported CsSnI<sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> and CsSnCl<sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> single junction counterparts.