Improving dispersibility of tungsten oxide particles with organic ligands for photochromic films

Abstract

Tungsten trioxide (WO3) has been studied as a promising photochromic material due to its favorable properties such as low manufacturing cost, high thermal and photostabilities, and low toxicity. Nevertheless, its practical application has been hindered by a relatively slow bleaching rate compared to other photochromic materials. Furthermore, metal oxide particles such as tungsten oxide face challenges in dispersing within process solvents, leading to difficulties in solution-based film fabrication processes. In this study, we aimed to address this limitation by exploring novel approaches to enhance both the dispersibility of tungsten oxides in processing solvents and their photochromic properties. To achieve this, we synthesized tungsten oxide composites by introducing various organic ligands, including polyvinylpyrrolidone (PVP), oleylamine (OA), hexadecylamine (HDA), and cetyltrimethylammonium bromide (CTAB). Through a comparative analysis, we found that the introduction of organic ligands significantly improved the dispersibility of tungsten oxides in processing solvents, while also enhancing their photochromic properties, including bleaching rate. Notably, the PVP ligand demonstrated superior performance in enhancing the overall properties of tungsten oxide composites. Our findings provide insights into the optimization of tungsten oxide-based photochromic materials for practical applications, offering potential directions for improvement and proposals for enhancing their performance and broadening their utility in various fields.