Intelligent Multifunctional VO₂/SiO₂/TiO₂ Coatings for Self-Cleaning, Energy-Saving Window Panels

TLDR

Monoclinic VO₂ thin films are attractive for intelligent solar‑control coatings that can reduce heating and cooling loads, but conventional CVD‑grown films suffer from poor adhesion, chemical instability, and limited transparency, hindering commercial adoption. This study aims to create a robust, multilayer VO₂/SiO₂/TiO₂ coating that simultaneously delivers strong solar‑modulation, high transparency, and abrasion resistance on glass panels. The coatings were fabricated by atmospheric‑pressure CVD, then characterized by XRD, Raman, and electron microscopy, and their component contributions were modeled to optimize performance. The resulting multilayer films exhibit ~30 % higher visible‑light transmission, double the solar‑modulation of single‑layer VO₂, superior thermochromic behavior, and self‑cleaning comparable to commercial Pilkington Activ glass.

Abstract

Monoclinic vanadium(IV) oxide (VO2) has received much attention for applications as intelligent solar control coatings, with the potential to reduce the need for both heating and air conditioning loads within building infrastructure. Chemical vapor deposition, a high-throughput industrially scalable method, is an ideal technology for the deposition of VO2 thin films on window panels. However, these films suffer from poor adhesion and are chemically susceptible to attack. In addition, the VO2 films with optimum solar modulation are unfortunately translucent, restraining their commercial use in energy-efficient fenestration. In this work, multifunctional, robust, layered VO2/SiO2/TiO2 films were quickly deposited on glass substrates using atmospheric-pressure chemical vapor deposition and fully characterized using structural, vibrational spectroscopy, and electron microscopy techniques. The VO2/SiO2/TiO2 thin films were designed to exhibit excellent solar modulation properties as well as high transparency and resistance to abrasion, compared to single VO2 films of the same thickness. The films also showed self-cleaning properties comparable to those of commercial Pilkington Activ glass, as demonstrated here during the photodegradation of a model organic pollutant (stearic acid). The SiO2 acted as a barrier layer, preventing the diffusion of Ti4+ ions into the VO2 layer but it also promoted the optical properties and allowed for superior thermochromic behavior when compared to single VO2 films. The system was modeled to determine the effect of the individual components on the properties of the overall material. It was found that the deposition of the SiO2/TiO2 overlayer resulted in a dramatic improvement of visible-light transmission (∼30% increase when compared to single-layer analogues) while also doubling the solar modulation of the material.