Unified Interface-Bulk Enhancements in Wide-Bandgap Perovskites Enabled by Bifunctional Cyanoacetic Acid for Textured...

Wide-bandgap (WBG) perovskite solar cells (PSCs) are essential for silicon/perovskite tandems but are hampered by buried-interface disorder, bulk defects, and ion-migration-induced degradation, challenges that are further amplified on textured silicon. We report a synergistic interface-bulk regulation strategy by incorporating cyanoacetic acid (CA) into both the self-assembled monolayers (SAM) and the perovskite precursor. At the buried interface, CA anchors to substrate and interacts with SAM, forming a molecular bridge that suppresses SAM aggregation and homogenizes interfacial energetics. Within the perovskite, CA coordinates with undercoordinated Pb²⁺ and stabilizes halides, producing uniform films with reduced trap densities. These enhancements strengthen the interface and suppress ion migration, nearly doubling the reverse-bias breakdown voltage. The textured silicon/perovskite interface exhibits enhanced and more balanced interfacial electric fields across silicon pyramids. The optimized 1.66-eV PSC achieves a steady-state power conversion efficiency (PCE) of 24.43%, while integration into textured silicon tandem device yields a champion PCE of 32.43% with 93% retention after 1000 h.