Efficient inverted HTL-free Sm2NiMnO6-based perovskite solar cell: a SCAPS-1D study

The transition to sustainable energy has driven extensive research into perovskite solar cells (PSCs) as promising candidates for next-generation photovoltaics. Despite their remarkable efficiencies, the commercialization of PSCs remains hindered by lead toxicity and material instability. In this study, we investigate a lead-free samarium-based double perovskite oxide, Sm₂NiMnO₆ (SNMO), as the active absorber layer in an innovative inverted, hole transport layer (HTL)-free PSC architecture. Using SCAPS-1D simulations, we optimized the device configuration and achieved a power conversion efficiency (PCE) of 10.93%, with an open-circuit voltage (V_OC) of 0.8 V, a short-circuit current density (J_SC) of 16.46 mA cm⁻², and a fill factor (FF) of 82.14%. Notably, increasing the SNMO absorber thickness enhanced light absorption in the red spectral region, shifting the external quantum efficiency (EQE) peak from 380 nm wavelength at a thickness of 50 nm to approximately  620 nm at 1 µm. Furthermore, we investigated various electron transport layers (ETLs) and found that the indium tin oxide (ITO) exhibited superior PV performances, boosting the PCE to ~ 12.6% due to its excellent conductivity and optimal energy band alignment with SNMO. These findings establish SNMO as a promising absorber material for environmentally friendly PSCs, paving the way for cheaper, simpler, scalable, and sustainable photovoltaic solutions. This work highlights the potential of HTL-free architectures to reduce costs and complexities while maintaining competitive efficiencies, marking a significant step forward in the development of lead-free solar technologies.