SCAPS-1D simulation of lead-free perovskite solar cells: performance analysis and optimization

Halide double perovskites have recently emerged as stable and non-toxic substitutes for lead-based materials in optoelectronic applications. Among these materials, Cs₂PtI₆ is distinguished by its high absorption coefficient, a bandgap (E _g) of 1.37 eV, and a long minority carrier diffusion length, due to its lower recombination rate, indicating an advantageous carrier lifetime and effective charge collection. Additionally, the appropriate selection of charge transport materials significantly enhances power conversion efficiency and overall performance. This work presents a theoretical evaluation of an n-i-p configured solar cell (FTO/SnO₂/Cs₂PtI₆/Spiro-OMeTAD/C), performed using the SCAPS-1D simulation tool. To optimize device performance, several parameters are systematically adjusted, including the thickness of the absorber layer, defect densities at the bulk and interface, the electrical resistances (series and shunt), and the selection of a suitable back contact material. Under standard conditions, the optimized device shows a remarkable power conversion efficiency (PCE) of 25.7%. Upon optimization, the spectral response shows a high quantum efficiency (QE) of 97.5% across the wavelength range. These results provide a significant theoretical understanding for improving the performance and design of perovskite solar cells.