Defect-Rich Boron-Doped Graphite for High-Performance Hole-Conductor-Free Mesoscopic Perovskite Solar Cells with Enhanced Back Interface Contact

Carbon-based hole-conductor-free perovskite solar cells (PSCs) exhibit promising potential on the road to commercialization for their low-cost production, scalable fabrication, and superior stability. However, the insufficient back interface contact between the carbon counter electrode (CE) and the perovskite is an urgent issue that hinders device performance. Herein, we report the preparation and application of defect-rich boron-doped graphite (BG) as the main CE medium for efficient printable mesoscopic PSCs (p-MPSCs). Boron doping induces the formation of abundant defective sites, including dangling bonds and oxygen-containing groups, onto the surface of graphite. These sites activate the inert surface and improve the surface affinity of CE with the perovskite. p-MPSCs based on BG achieve a firm interfacial contact, which improves the power conversion efficiency from 17.94% to 19.43% by enhancing charge collection.