Solution‐Processed Zinc‐Tin‐Based Ternary Oxide Electron Transport Layers for Planar Perovskite Solar Cells

Perovskite solar cells (PSCs) have acquired popularity owing to their high efficiency, ease of fabrication, and affordability. In this context, the development of electron transport layers (ETLs) for highly efficient planar photovoltaic devices has received considerable attention. This study investigates the potential of zinc‐tin‐based ternary metal oxide ETLs for application in planar PSCs. Solution‐processed methods are used to fabricate crystalline zinc stannate (Zn 2 SnO 4 ), amorphous zinc‐tin oxide (ZTO), and Zn 2 SnO 4 /ZTO‐based bilayer films, and their structural, morphological, and optoelectronic properties are thoroughly studied. X‐ray diffraction (XRD) analysis and scanning electron microscopy (SEM) images show enhanced crystallite size and better surface morphology of perovskite films deposited on bilayer ETL. Photoluminescence (PL) studies and Hall effect measurements reveal superior charge extraction, improved charge carrier mobility (21.84 cm 2 V −1 s −1 ) and enhanced n‐type conductivity in the bilayer ETL. Moreover, contact angle analysis of perovskite layer deposited on bilayer ETL shows increased resistance to moisture erosion (52.20°), which is particularly significant given the detrimental effects moisture can have on the performance of PSCs.