Numerical modeling and extensive analysis of an extremely efficient RbGeI3-based perovskite solar cell by incorporating a variety of ETL and HTL materials to enhance PV performance

The immense demand for electrical energy motivated us to manipulate solar energy by means of conversion through solar cells (SCs). Advancements in photovoltaic (PV) technology are occurring very rapidly. In recent years, extensive research has been conducted on halide perovskite-based SCs because of their superior optoelectronic properties, enhanced efficiency, lightweight nature, and low cost. However, concerns have arisen regarding their longevity, stability, and commerciality due to the presence of toxic lead (Pb). The most prominent purpose of this investigation is to discover additional efficient, sustainable, and eco-friendly device architectures. In this study, we investigated an all-inorganic, lead-free rubidium germanium iodide (RbGeI₃)-based PSC device with the assistance of the SCAPS-1D simulator. Several electron transport layers (ETLs) and hole transport layers (HTLs) were incorporated with the perovskite layer, and an efficient primary structure was discovered. Then, the impact of temperature; back metal work function; series and shunt resistance; surface recombination velocity of carriers; thickness of the perovskite absorber layer, electron transport material (ETM), and hole transport material (HTM); carrier concentration of the perovskite absorber layer, ETM, and HTM; defect density of the perovskite absorber layer, ETM, and HTM; and defect density of the HTL/absorber and absorber/ETL interfaces on the PV performance of the proposed PSC device was analyzed. The optimized device exhibited a power conversion efficiency (PCE) of 30.35%, with superior values for open circuit voltage (V_oc), short circuit current density (J_sc), and fill factor (FF) of 1.067 V, 33.15 mA cm⁻², and 85.82%, respectively. The investigations in this study may be valuable and impactful to solar cell material researchers and move the research interest forward by one step so that experimental work with non-toxic RbGeI₃-based PSC devices will be performed in the future.