Hexagonal cesium tungsten bronze nanoparticles produced by solvent-free spray pyrolysis and their near infrared absorption properties

Abstract

Cesium tungsten bronze (Cs_0.32WO₃) nanoparticles (NPs) have attracted attention as a transparent near-infrared (NIR) absorbing material. In this study, a solvent-free aerosol method, namely solid-fed spray pyrolysis, was applied for the synthesis of Cs_0.32WO₃ NPs. Optimising the reaction temperature and H₂ concentration in the carrier gas led to highly crystalline Cs_0.32WO₃ NPs with well controlled stoichiometry. The obtained Cs_0.32WO₃ NPs exhibited 13.7% NIR transmittance at 1425 nm with 80% visible light transmittance; these NIR absorption properties were superior to those of the Cs_0.32WO₃ NPs produced by a liquid-fed spray pyrolysis method. This improvement was examined in terms of the crystal structure and the mechanism of particle formation.