Calotropis-mediated biosynthesis of TiO2@SnO2/Ag nanocomposites for efficient perovskite photovoltaics

Abstract

In this study, green SnO2@TiO2 nanocomposites were initially synthesized using an extract from the Calotropis plant as an electron transfer material for fabricating perovskite solar cells (PSCs). Further, plasmon impregnation (Ag-NPs) into the SnO2@TiO2 nanocomposites yielded nanocomposite (TiO2@SnO2/Ag) films. The effect of doping silver into the SnO2@TiO2 nanocomposites was investigated in detail to gain insights into how it influences the photovoltaic performance of the PSC. It resulted in enhanced quenching of photoluminescence compared to TiO2 and TiO2@SnO2 electron transport layers (ETLs), indicating faster charge extraction. PSCs utilizing the TiO2@SnO2/Ag ETL showed significantly improved performance with a power conversion efficiency of 22.2 %, a higher fill factor, and reduced hysteresis compared to cells with TiO2 and TiO2@SnO2 ETLs. The characterization of the nanocomposites revealed that the TiO2@SnO2/Ag ETL led to perovskite films with improved crystallinity, morphology, charge separation, and transfer properties. Electrochemical impedance spectroscopy confirmed the TiO2@SnO2/Ag ETL facilitated faster charge transfer and lower recombination at interfaces. Finally, the TiO2@SnO2/Ag ETL-based devices exhibited superior long-term stability in air, maintaining over 87 % of their initial efficiency. This work demonstrates that the incorporation of TiO2@SnO2/Ag nanocomposites is effective for developing high-performance and stable PSCs.