Crystalline NiO:N Templating of Uniformly Anchored Self-Assembled Monolayers for Inverted Perovskite Solar Cells

Abstract The buried hole-selective contact in inverted perovskite solar cells (PSCs) is expected to transport holes through its bulk while also templating a defect-free self-assembled monolayer (SAM). A crystalline, vacuum-deposited nitrogen-doped NiO (NiO:N) film deterministically templates a uniformly anchored SAM, while the reactive-atmosphere N2/O2 ratio used during pulsed laser deposition (PLD) simultaneously programs bulk hole density and interfacial anchoring chemistry. Nitrogen incorporation is proposed to act as a shallow acceptor that generates Ni3+ states and raises p-type conductivity, whereas the dense, pinhole-free template enforces uniform SAM coverage, fully suppressing the underlying substrate signal and minimizing surface hydroxyl groups relative to discontinuous nanoparticle films. Consequently, NiO:N/SAM-based PSCs achieve a 6.2% relative increase in power conversion efficiency (PCE) over pristine NiO nanoparticles, reaching one of the highest reported performances for vacuum-deposited NiO-based PSCs, with improved thermal and operational stability. These results establish reactive-atmosphere NiO:N as a general, scalable platform for hole-selective contacts in inverted perovskite photovoltaics.