Solution‐Processed Perhydropolysilazane for Advanced Silica Coatings: From Conversion Mechanisms to Next‐Generation Device Integration

ABSTRACT Perhydropolysilazane (PHPS) provides a unique solution‐based route for fabricating silica coatings through the direct conversion of an inorganic polymer precursor into an amorphous Si–O–Si network. Unlike conventional sol–gel systems, PHPS forms silica through the transformation of a pre‐existing Si–N framework. Thermal oxidation, catalytic hydrolysis, and photochemical activation involve distinct reaction pathways for bond cleavage and network formation, which determine network topology, residual species, and densification of the resulting silica films. Understanding these conversion‐dependent structural evolutions is therefore critical for tailoring the functional performance of PHPS‐derived coatings. This review summarizes the synthesis and physicochemical characteristics of PHPS, followed by discussions of the fundamental mechanisms governing thermal, catalytic, and photochemical conversion. Recent advances in reactive molecular dynamics simulations are highlighted to provide atomistic insights into the conversion process. The relationships among conversion chemistry, microstructural evolution, and material properties are further examined to elucidate the performance of PHPS‐derived silica in microelectronic dielectrics, environmental barrier coatings, heterogeneous interface engineering, and functional composite systems. Finally, current challenges in conversion control, structural regulation, and scalable processing are discussed to outline future opportunities for advancing PHPS‐derived inorganic coatings in next‐generation electronic, energy, and manufacturing technologies.