Exploring Optoelectronic Behavior and Solar Cell Efficiency of Double Halide Perovskites MKIrCl (M = Cs, Rb) through DFT and SCAPS-1D.

Due to environmental concerns with lead-based perovskite solar cells (PSCs), attention has shifted toward safer alternatives like MKIrCl (M = Cs, Rb). This study extensively investigates the structural, electronic, and optical properties of MKIrCl using density functional theory (DFT). The analysis evaluates the suitability of these compounds as absorber materials in solar cells, emphasizing their environmental friendliness, stability, and efficiency for light-harvesting applications. The structural stability of MKIrCl double halide perovskites is analyzed using tolerance factors (τ, μ, τ), with dynamical stability confirmed via phonon dispersion analysis. Negative formation energy () and binding energy () further corroborate their thermodynamic stability. The direct band gaps calculated using both GGA-PBE and TB-mBJ methods were found to be 1.08 and 1.99 eV for CsKIrCl, and 1.12 and 2.10 eV for RbKIrCl, respectively. These bandgap values fall within the optimal range (0.8-2.2 eV) necessary for efficient photovoltaic conversion, showcasing their capability to serve as absorber layers in photovoltaic devices. Furthermore, these compounds demonstrate exceptional optical properties, including high absorption coefficients (∼10 cm), low energy losses, and minimal reflectivity (<15%), emphasizing their suitability for advanced optoelectronic and photovoltaic applications. To optimize solar cell performance, SCAPS-1D software was utilized to investigate various device configurations incorporating different Hole Transport Layers (HTLs) and Electron Transport Layers (ETLs). Among 32 configurations tested, the ITO/ZnO/CsKIrCl/VO structure reached a peak power conversion efficiency (PCE) of around 21.30%, while the ITO/ZnO/RbKIrCl/VO configuration exhibited around 18.30%. Additionally, the impact of ETL and absorber layer thicknesses, series and shunt resistances, and operating temperatures on device performance was thoroughly explored. Crucial photovoltaic metrics, including current density-voltage (-) curves, capacitance, quantum efficiency, Mott-Schottky characteristics, and photocarrier generation-recombination rates, were comprehensively analyzed, underscoring the remarkable potential of MKIrCl as efficient and cost-effective materials for future solar energy and optoelectronic applications.