Post-Treated NiO _<i>x</i> with 1-Dodecanethiol for Enhanced Interfaces in Inverted Perovskite Solar Cells

Nickel oxide (NiOx) is widely recognized as an effective hole-transport layer for inverted perovskite solar cells (PeSCs); nevertheless, its performance is often hindered by the transformation of Ni2+ to Ni3+, which generates interfacial defect states and accelerates nonradiative recombination. To address this issue, we introduce a thiol-based interfacial passivation strategy using 1-dodecanethiol (DDTH) at the NiOx/perovskite junction. The strong coordination between thiol groups and nickel atoms forms robust Ni–S bonds, effectively passivating interfacial defects and stabilizing the NiOx surface. This interfacial modification suppresses nonradiative recombination, enhances hole extraction, and improves energy-level alignment across the interface. Consequently, DDTH-treated devices exhibit markedly improved charge transport and reduced interfacial losses. An optimized device incorporating 0.5 mg mL–1 DDTH achieves a power conversion efficiency (PCE) of 19.3% and retains 80% of its initial efficiency after 500 h of one-sun illumination at room temperature (≈27 °C), demonstrating markedly enhanced operational stability.