Abstract Several electronic devices, such as perovskite solar cells (PSCs) and organic light-emitting diodes (OLEDs), are very vulnerable to water vapor. Therefore, they require an ultrahigh-performance gas barrier (water vapor transmission rate [WVTR]: less than 10−5 g m−2 d−1). The barrier performance of solution-processed gas barriers is inferior to that of vacuum-processed gas barriers; however, they possess advantages such as high resource efficiency, high throughput, low fabrication cost, and printability, which facilitate sustainable manufacturing and digital fabrication. The simultaneous realization of solution processability and ultrahigh barrier performance is highly desired. Herein, this work reports solution-processed gas barriers developed using perhydropolysilazane (PHPS)-derived SiN (PDSN) layers densified by vacuum ultraviolet (VUV) irradiation in a nitrogen atmosphere at room temperature. The appropriate PDSN thickness and irradiated VUV dose result in an excellent WVTR of 4.8 × 10−5 g m−2 d−1 (a barrier performance close to that of glass), which makes it among the best-performing water vapor barriers recorded to date. The barrier performance is achieved with a thickness of only 990 nm and a short VUV irradiation time (2.4 min per PHPS layer). An ultrahigh-performance barrier with rapid processability such as this expands the possibility of solution-processed barrier technology.
