Solvent‐Assisted Surface Modification Using Metallocene‐Based Molecules for High‐Efficiency Perovskite/Silicon Tandem Solar Cells

Abstract The presence of a high density of defects at the perovskite/electron transport layer (ETL) interface results in significant nonradiative recombination losses, thus impeding the efficiency enhancement of perovskite/silicon tandem solar cells (TSCs). In this investigation, a metallocene‐based molecule, cobalt (III) dichlorophene hexafluorophosphate (CcPF 6 ), is employed for perovskite surface passivation. To maximize its efficacy, the molecule is dissolved in a mixed solvent of acetonitrile and chlorobenzene, leading to the reconstruction of the perovskite surface and effective passivation of surface defects. This modification strategy substantially enhances the overall efficiency of perovskite/silicon tandem solar cells by mitigating the issue of low fill factor resulting from non‐uniform coating of the top perovskite layer on the textured silicon bottom cell. Leveraging a double‐sided textured silicon heterojunction (HJT) bottom cell, a certified power conversion efficiency (PCE) of 30.43% for a monolithic perovskite/silicon TSC (1.00 cm 2 ) is achieved, featuring an open‐circuit voltage ( V oc ) of 1.93 V and a fill factor ( FF ) of 78.43%. After storage in the drying cabinet (5% humidity at 20 °C) for 1000 h, the device retains 94.27% of its initial performance.