Tuning the Photochromic Properties of WO₃-Based Materials toward High-Performance Light-Responsive Textiles

The development of photoresponsive textiles with high color contrast, sunlight response, fast coloration/bleaching, and reversible properties has been a major quest for anticounterfeiting, camouflage, UV protection, and fashion. WO3 materials are promising building blocks for textile applications, but their application has been limited by their slow color bleaching under ambient conditions and limited sunlight response. Herein, innovative tungsten oxide-based materials with tunable photochromism were produced by a low-cost, single-step, and scalable solvothermal process in the presence of different structure-directing agents, and the most promising ones were screen-printed on fabrics to produce light-responsive smart textiles. The influence of the structure-directing agent type (polyethylene glycol, hexadecyltrimethylammonium bromide, polyoxyethylene(10) cetyl ether, Pluronic F127, and polyvinylpyrrolidone (PVP)) on the morphology, structure, composition and photochromism of the WO3-based materials was assessed, toward enhancing their color contrast and coloration/bleaching rates and endowing a sunlight response. All WO3-based materials exhibited UV/sunlight-responsive properties, with the materials prepared with PVP presenting the best performance, featuring 13× faster coloration than that of other WO3-based materials reported in the literature (7 min vs 60–90 min) and up to 2× higher total color difference (21.4–50.6 vs 25.2–25.8). These improvements were assigned to their Lindqvist-type hexatungstic acid structure hybridized with PVP, while the remaining materials were composed of WO3·H2O and WO3. The WO3_PVP-based materials led to high-performance photoswitchable textiles under sunlight and UV irradiation, changing color from white to blue in 3–7 min and bleaching in 3–7 h. The smart textiles presented fast hydrobleaching, especially the fabric based on WO3 prepared using PVP with higher molecular weight, which hydrobleached in up to 20 s, surpassing reported works on WO3-modified fibers. This work opens horizons for the design of engineered UV/sunlight-responsive WO3-based materials and textiles with hydrobleaching properties through straightforward scalable processes, offering potential prospects for smart clothing and optical sensors.