Perovskite solar cells (PSCs) are among the most promising next generation photovoltaic technologies due to their high efficiency and low-cost manufacturing potential. A key challenge for industrial commercialization is the development of scalable, stable and reproducible charge transport layers compatible with large-area manufacturing. In this work, we demonstrate the incorporation of sputtered NiOx as an inorganic hole transport layer (HTL), providing a robust and scalable alternative to conventional solution-processed organic HTLs for ambient-processed perovskite solar cells.

Sputtered NiOx HTLs were systematically optimized by tuning deposition parameters, film thickness and post-treatment conditions to enhance conductivity, interfacial quality, and compatibility with perovskite deposition. NiOx films were investigated in as-sputtered, 140°C-annealed, and 300°C-annealed states to define processing windows suitable for both high-performance rigid devices and low-temperature flexible substrate manufacturing. In parallel, perovskite absorber layers were deposited under ambient atmospheric conditions using environmentally friendly green solvent formulations enabling safer and more sustainable fabrication compared with conventional toxic solvent systems.

The integration of optimized sputtered NiOx with ambient green-solvent processed perovskite films resulted in uniform, high-quality layers with excellent crystallinity and surface coverage. Under optimized conditions, blade-coated rigid devices achieved efficiencies up to 19%, demonstrating the strong photovoltaic potential of the material system. At scalable sheet-to-sheet (S2S) slot-die level, devices reached efficiencies up to 14%, confirming successful transfer toward industrially relevant manufacturing. The reduced efficiency at S2S scale is mainly attributed to the transition from optimized lab-scale electrode architectures to scalable contact stacks, which introduce additional interfacial and resistive losses. In addition, as-sputtered NiOx enabled mini-module fabrication with efficiencies of 6%, demonstrating module-scale compatibility without thermal post-treatment. Promising damp-heat and light-soaking stability under accelerated aging conditions further confirm the robustness of the developed architecture.

Finally, the compatibility of optimized sputtered NiOx and ambient green-solvent perovskite processing was validated across glass, PET, and metal foil substrates, highlighting versatility for both rigid and flexible photovoltaic applications. These results establish sputtered NiOx HTLs as a key enabling technology for scalable, sustainable and industrially relevant perovskite solar cell manufacturing.