Dual-oxide WO3-Based ETLs for enhanced charge transport and stability in CsPbIBr2 perovskite solar cells

Abstract

This study is significant for introducing WO₃-based composite ETLs (ZrO₂-WO₃ and SnO₂-WO₃) that synergistically enhance charge transport, reduce recombination, and improve stability in CsPbIBr₂ perovskite solar cells. The novelty lies in the dual-oxide approach, which leverages the complementary structural and electronic properties of WO₃ with ZrO₂ and SnO₂ to achieve higher device efficiency. X-ray diffraction (XRD) analysis confirmed the successful integration of WO₃-based films, with calculated crystallite sizes of 36.5 nm for ZrO₂-WO₃ and 41.8 nm for SnO₂-WO₃, indicating improved crystallinity for the SnO₂-based film. Scanning electron microscope (SEM) showed that SnO₂-WO₃ film exhibits a smoother, more uniform morphology with smaller grain sizes compared to the ZrO₂-WO₃ film. Raman spectroscopy validated the phase purity and chemical stability of the prepared films. SEM morphology showed the reduced average grain size for SnO₂-WO₃ film. UV–Vis (UV–vis) spectroscopy revealed reduced band gaps of 2.71 eV and 2.69 eV for ZrO₂-WO₃ and SnO₂-WO₃, respectively, favoring efficient charge transport. Photoluminescence (PL) measurements demonstrated enhanced charge carrier separation. Current-density voltage (J-V) characteristics showed a higher power conversion efficiency of 9.35 % for SnO₂-WO₃ compared to 8.26 % for ZrO₂-WO₃. Electrochemical impedance spectroscopy (EIS) revealed reduced charge transfer resistance and increased recombination resistance (1769 Ω) for SnO₂-WO₃-based devices. These findings highlight the potential of WO₃-based ETLs in PSCs for future high-efficiency photovoltaic applications.