Computational study of nontoxic Cs2PtI₆ double perovskite as a lead-free photovoltaic absorber

Cesium platinum iodide (Cs 2 PtI 6 ), a lead-free (Pb-free) double perovskite absorber, has been studied in comparison with existing lead-based (Pb-based) absorbers, specifically the commonly used methylammonium lead iodide (MAPbI 3 ). This study aims to explore the potential use of Cs 2 PtI 6 as a replacement for toxic Pb-based and other nontoxic Pb-free perovskite absorbers by employing a numerical method. The objectives include the numerical modeling of an existing experimental device, FTO/CdS/Cs 2 PtI 6 /C 60 /Cu, without the addition of an interface defect layer (IDL) at the CdS/Cs 2 PtI 6 and Cs 2 PtI 6 /C 60 interfaces. Experimental and numerical data from the literature are utilized to validate the findings and enable comparison with MAPbI₃-based devices. Additionally, to optimize both Cs 2 PtI 6 - and MAPbI 3 -based devices, parameters such as absorber thickness, operating temperature, series resistance (R S ), shunt resistance (R SH ), absorber interface defects, doping densities, Cs 2 PtI 6 bandgap, and the thicknesses of the hole transport layer (HTL) and electron transport layer (ETL) are analyzed. Subsequently, the Cs 2 PtI 6 -based device is modeled with various ETLs and HTLs to achieve an optimized combination. These findings validate the experimental study of FTO/CdS/Cs 2 PtI 6 /C 60 /Cu and the numerical method of FTO/CdS/IDL1/Cs 2 PtI 6 /IDL2/C 60 /Cu. Based on the optimized parameter values, aligned with ideal performance limits defined by solar cell physics, the device structures TCO/TiO 2 /Cs 2 PtI 6 /MoO 3 /Ni and ITO/ZnO/Cs 2 PtI 6 /CBTS/Ni are identified as the best-performing devices, with power conversion efficiencies (PCEs) of 30.04 % and 31.66 %, respectively. These results demonstrate that Cs 2 PtI 6 has the potential to outperform both other Pb-free and Pb-based absorbers. • The impact of several parameters on the performance of Cs 2 PtI 6 -based (and MAPbI 3 -based) solar devices is studied. • The optimization of Cs 2 PtI 6 -based solar device significantly improves the device’s performance. • The Cs 2 PtI 6 -based solar device, exhibits low recombination rate and high voltage, yielding overall efficiency of ∼30 %. • The superior efficiency of Cs 2 PtI 6 -based solar devices highlights its potential for advanced photovoltaic applications. • The importance of precise energy-band engineering in advancing perovskite-based photovoltaic devices is demonstrated.