Robust Ionic Anchoring at NiOx Interfaces Enables Efficient Outdoor and Indoor Inverted Perovskite Solar Cells

The interfacial chemistry between hole-selective contacts (HSCs) and oxide substrates plays a critical role in governing charge extraction, interfacial recombination, and operational stability in inverted perovskite solar cells (PSCs). We designed three carbazole-based HSCs that share a D-π-A backbone but differ systematically in anchoring group chemistry and molecular ionicity: a neutral pyridine (HSC-N), a zwitterionic N-oxide (HSC-O), and an ionic pyridinium salt with a pendant carboxyethyl group and Br- counterion (HSC-A), respectively. This molecular design isolates the anchoring-group effect and correlates it with interfacial energetics, dipole modulation, and device performance. Increasing molecular ionicity greatly enhances the dipole moment from 3.98 D for HSC-N to 17.11 D for HSC-A, effectively tuning the NiOx surface energetics and promoting directional charge transport. After DMF/DMSO rinsing, HSC-A retained 72% of its initial surface loading, sufficient to deepen the valence band maximum at the NiOx interface and most effectively suppress non-radiative recombination. Together, these effects yield champion PCEs of 21.42% and 19.52% for 1.57 eV and 1.68 eV perovskite absorbers, respectively. Under 1000-lux indoor illumination, HSC-A-based devices achieve an average PCE of 40.47% and retain nearly their initial efficiency after 34 days in ambient air. These results directly link anchoring-group design to device performance, highlighting ionic pyridinium-carboxylate contacts as an effective strategy for high-performance inverted PSCs.