SnO ₂ as Electron Transport Layer in CsPbBr ₃ Perovskite Solar Cells: Experimental and Simulation Approaches

Combined experimental and simulation-based studies have been conducted to evaluate the role of electron transport layers (ETLs) in cesium lead bromide (CsPbBr3) based perovskite solar cells. CsPbBr3 thin films are fabricated through a multistep spin-coating method and are characterized using XRD, HR-SEM, UV–vis absorption, and infrared spectroscopy. The performance of TiO2 and SnO2 as ETLs is systematically unveiled for better layering to obtain higher efficiency. SnO2-based device demonstrates a higher power conversion efficiency (PCE) of 4.97% (VOC = 1.10 V, JSC = 7.98 mA/cm2, FF = 55.92%), outperforming the TiO2-based device with a PCE of 3.86% (VOC = 1.10 V, JSC = 7.88 mA/cm2, FF = 43.94%). Device-to-device uniformity is confirmed by the intrabatch variation of PCE for multiple runs, with a variation of ±2%, indicating excellent reproducibility of the devices. Numerical simulations are further employed to examine the influence of absorber thickness, bulk and interfacial defect densities, series resistance, and operational temperature on device performance. The simulation studies show that the SnO2-based structure with Spiro-OMeTAD as the hole transport layer (HTL) achieves a maximum PCE of 8.08%. These experimental and theoretical insights confirm that SnO2 functions as a superior ETL compared to TiO2, thereby enabling the development of efficient and stable CsPbBr3 perovskite solar cells under ambient conditions.