Transforming Device Efficiency and Stability in NiO‐Sputtered n–i–p Perovskite Solar Cells by Soft‐Landing and a Thin Spiro‐OMeTAD Buffer Layer

ABSTRACT The integration of inorganic materials in perovskite solar cells (PSCs) is critical for enhancing long‐term operational stability, scalability, and economic viability. Here, we demonstrate the transformational efficacy of using a modified protocol for sputtered nickel oxide as a hole transport layer (HTL) in n–i–p structured PSCs, in conjunction with a thin Spiro‐OMeTAD buffer layer. The introduction of a biased grid and a buffer interface enable us to achieve a soft landing of NiO on the halide perovskite, thereby minimizing process‐induced interfacial damage. Our results indicate that the buffer layer serves solely as an interfacial protection layer, rather than as a functional HTL. Using this approach, we report champion power conversion efficiencies of 23.45% (mean ≈22.2%) on rigid glass substrates and 22.1% (mean ≈21%) on flexible ITO‐coated PET substrates, both employing fully inorganic charge transport layers. These results represent unprecedented enhancements over previously reported highest PCE values (<12%) for n‐i‐p devices using sputtered NiO as the HTL, placing them on par with p‐i‐n architectures that utilize a combination of NiO and organic HTLs. This work demonstrates a scalable, commercially viable pathway toward high‐efficiency, stable perovskite photovoltaics based solely on sputtered inorganic layers, offering a competitive edge for further development.