Highly efficient double halide perovskite for solar cell devices with DFT and SCAPS 1D analysis

Advancing sustainable photovoltaic technologies depends greatly on the development of high-performance perovskite solar cells (PSCs), and new materials continue to provide promising opportunities for improving device efficiency. This research investigates the double perovskite compound Cs 2 TlRhI 6 as a potential light-harvesting material through first-principles calculations and device-level simulations. The material has a direct bandgap of 1.12 eV, a refractive index of about 3.1, low reflectivity (below 30%), and strong absorption in the visible range, all of which support its potential for photovoltaic applications. Furthermore, implementing our absorber in an optimized device structure, employing Cu 2 O as the HTL and IGZO as the ETL, achieves a PCE of 25.78%, with a J SC of 40.53 mA/cm 2 , a V OC of 0.79 V, and a FF of 80.40%. Temperature analysis indicates a slight reduction in performance at high temperatures, revealing good thermal stability of the device. This work opens up Cs 2 TlRhI 6 as a promising and structurally stable material for future PSCs.