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

ABSTRACT 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.