Abstract
Tungsten trioxide (WO(3)) is a well-known photochromic material that undergoes a reversible color change under light irradiation, making it promising for applications in smart windows, optical storage, and sensing devices. This study presents the successful synthesis of a uniform and morphology-controlled WO(3) neural network-like structure by tuning the hydrothermal reaction temperature and hydrochloric acid concentration. Furthermore, the photochromic response time of the as-prepared WO(3) particles was systematically investigated, and the optimal sample exhibiting the fastest response was identified. To significantly enhance the photochromic performance, erbium (Er), a rare earth element, was introduced as a dopant. According to the results, Er doping significantly prolonged the photochromic response time of WO(3). The incorporation of Er led to a noticeable narrowing of the optical bandgap, as confirmed by UV-vis absorption and Tauc analysis. The Er(0.03)W(0.97)O(3) composition demonstrated superior performance compared to the other analyzed samples, indicating that the incorporation of rare earth elements can effectively regulate the photochromic behavior of WO(3) and provide a new pathway for tailoring its optical properties.