Co‐Assembled Layers for High Performance Wide Bandgap Inverted Perovskite Solar Cells

Wide-bandgap perovskite solar cells are ideal top-cell candidates for tandem photovoltaics, yet their performance is bottlenecked by severe interfacial voltage losses and light-induced degradation. Here, we incorporate aminoguanidine dihydrochloride into the widely used Me-4PACz self-assembled hole-transport layer, forming a co-assembled layer (AH-SAM), in which AH engages in cation-π coupling with Me-4PACz's carbazole core and electrostatic interactions with its phosphate group. AH-SAM lowers the HTL's highest occupied molecular orbital and markedly boosts its UV resistance. Concurrently, aminoguanidine dihydrochloride passivates halide vacancies, suppresses Me-4PACz aggregation, and perfects interfacial contact. These improvements enable open-circuit voltage of 1.27 V for a 1.67 eV wide-bandgap perovskite device, demonstrating one of the lowest reported open-circuit voltage deficits (0.40 V), achieving a power conversion efficiency of 22.97%. Furthermore, AH-SAM strategy can significantly enhance the operational stability of PSCs, retaining 96% of the initial efficiency after 1,000 h of maximum power point tracking under 1 sun illumination. This work demonstrates the advantage of AH-SAM strategy in improving the performance and stability of Perovskite solar cells, energy level alignment., interface passivation, self-assembled monolayers, wide-bandgap perovskitewide-bandgap perovskite solar cells.