Strategic design and evaluation of charge transport layers for high-efficiency lead-free BeSiP2-based perovskite solar cells: A careful examination into electron and hole transport layers

This research looks into a new, eco-friendly way to make perovskite solar cells (PSCs) that uses a lead-free BeSiP2 absorber layer. Similar to their lead-based counterparts, silicon-based perovskites have important optoelectronic properties, such as a high absorption coefficient and a long carrier diffusion length. We investigated four electron transport layers (ETLs-IGZO, PCBM, TiO2, and WS2), three-hole transport layers (HTLs-CuI, CuO, and CBTS), and three device configurations to find the optimum structure by SCAPS-1D simulator. The Al/FTO/IGZO/BeSiP2/ CuI/Au, Al/FTO/IGZO/BeSiP2/CuO/Au, and Al/FTO/IGZO/BeSiP2/CBTS/Au are considered as Devices-I, II, and III. The proposed PSC architecture consists of Al/FTO/IGZO/BeSiP2/CBTS/Au, where CBTS acts as the HTL and indium-gallium-zinc-oxide (IGZO) serves as the ETL. CBTS is recognized for its inexpensive cost and superior electrical conductivity, which facilitate effective hole transfer. Including IGZO as the ETL guarantees effective electron transport because of its crystalline structure's compatibility with BeSiP2, while minimizing defects of the interface, making it a crucial element of the layout. Important variables like acceptor density and absorber layer thickness are tuned, along with a thorough examination of the density of the defect, defects of the interface at the ETL/absorber and HTL/absorber, and series and shunt resistances. By meticulously adjusting these parameters, the solar cell achieves a power conversion efficiency (PCE) of 31.97 %, an open circuit voltage (VOC) of 1.063 V, a short circuit current density (JSC) of 34.44 mA/cm2, and a fill factor (FF) exceeding 87.33 % among the visible range of the light spectrum, underscoring the potential of this efficient, sustainable, and economical solar cell alternative.