Perhydropolysilazane as a Precursor for Solution-Processed Silicon-Based Materials: Synthesis, Conversion Routes and...

Perhydropolysilazane (PHPS) has attracted considerable attention as a versatile precursor for solution-processed silicon-based materials because of its carbon-free backbone, high chemical reactivity, and compatibility with low-temperature processing. This review provides a comprehensive overview of the synthesis of PHPS, its conversion routes and mechanisms, the structure-property relationships of PHPS-derived materials, and their current and emerging applications. The literature demonstrates that PHPS conversion is governed by coupled hydrolysis, oxidation, nitridation, dehydrogenation, photochemical activation, and reactive-species-mediated processes, resulting in compositionally and structurally diverse silicon-based networks, including SiO_x-rich, SiO_xNᵧ, and SiN_x materials. The resulting optical, mechanical, surface, and barrier properties are determined by network structure, residual bonding environments, compositional gradients, and interfacial characteristics rather than by the nominal conversion method alone. Recent advances further demonstrate the potential of PHPS-derived materials for barrier coatings, dielectric and interfacial layers, protective coatings, semiconductor processing, and high-temperature ceramic applications. Overall, PHPS should be regarded not merely as a silica precursor but as a tunable preceramic platform for engineering diverse silicon-based networks. Future progress will depend on predictive control of conversion processes, standardized evaluation protocols, sustainable solution-based manufacturing, and comprehensive device-level validation to facilitate practical implementation.