Inkjet‐Printed SiO _x N _y Barrier Film for Encapsulation of Perovskite Solar Cells

ABSTRACT Thin‐film encapsulation is a suitable method for enhancing the environmental stability of perovskite solar cells (PSCs) against oxygen and moisture. In this work, inkjet printing of perhydropolysilazane (PHPS) solution was first adopted to fabricate silicon oxynitride (SiO x N y ) barrier films, which were converted from PHPS via vacuum ultraviolet (VUV) treatment. The transformation process was confirmed by Fourier transform infrared spectroscopy and X‐ray photoelectron spectroscopy. Experiment results revealed that multiple thin‐layer deposition enables the formation of a more uniform surface ascribed to the synergistic effect of surface energy tuning and precursor self‐leveling during layer‐by‐layer printing. The improved thin film morphology ensures better barrier properties of the barrier films, as proved by the water immersion test on perovskite films. The inkjet‐printed SiO x N y film encapsulation process demonstrated exceptional compatibility with PSCs owing to the conformal coating and low‐temperature processing (< 80°C). The encapsulated PSCs retained 93% ± 5% power conversion efficiency after 1000 h storage under 25°C/60%RH environment (ISOS‐D‐1 protocol) and 80% ± 13% after 1 h water immersion. The stability results demonstrate inkjet printing is a viable encapsulation strategy for perovskite photovoltaics, offering (i) precise pattern control (line width of 59.4 ± 5.0 µm), (ii) room‐temperature processing compatibility, and (iii) scalable manufacturing potential.