# Polysilazane-Derived Layer for Enhancing Durability of Yttrium Oxyhydride Photochromic Coatings

## TL;DR

This paper explores using a special coating to protect a photochromic material, improving its durability for smart window applications.

## Contribution

The study introduces PHPS-derived SiOxNy coatings as a novel protective layer for YHO photochromic films.

## Key findings

- SiOxNy coatings effectively protect YHO from environmental degradation.
- Photochromic performance is preserved with minimal loss in coated configurations.
- PHPS-derived layers show potential as multifunctional barriers for smart coatings.

## Abstract

Yttrium oxyhydride (YHO) exhibits photochromic properties
under
ambient conditions, making it a promising material for smart window
applications. However, operational challenges including lattice contraction
upon illumination, expansion during bleaching, and limited thermal
stability introduce mechanical stress and susceptibility to degradation
from environmental gases, compromising long-term performance. This
study investigates perhydropolysilazane (PHPS)-derived SiOxNy coatings as a solution for environmental protection
of PHPS. A silicon–nitrogen–hydrogen preceramic polymer
was deposited via spin coating and UV-cured on glass substrates, followed
by reactive magnetron sputtering of YHO thin films. Three configurations
glass/SiOxNy/YHO, glass/SiOxNy/YHO/SiOxNy, and glass/YHO/SiOxNy were evaluated under solar simulator illumination,
with optical performance characterized by UV–vis spectrophotometry.
The results reveal that SiOxNy coatings effectively
shield YHO from environmental degradation while preserving its photochromic
response. Minimal performance loss across coated architectures underscores
the potential of PHPS-derived layers as multifunctional barriers,
advancing the durability and applicability of YHO-based smart coatings.