In situ facile one-step solvothermal synthesizing hexagonal ammonium tungsten bronze (NH4)0.33WO3 to tap NIR light absorption ability by controlling crystallinity

Tungsten bronze (TB) has potentially high visible light transparency and excellent near-infrared (NIR) shielding ability. To fully dig out the concealed optical properties of TB with specific chemical components, in this work, hexagonal ammonium tungsten bronze (h-ATB) (NH4)0.33WO3 was fabricated by a one-step solvothermal reaction. Through X-ray diffractometer (XRD), scanning electron microscope (SEM), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), and ultraviolet–visible–near infrared (UV–vis–NIR) spectroscopy to characterize h-ATB, which unraveled that controlling crystallinity could adjust the optical property of h-ATB. In particular, when the crystallinity of the h-ATB is over 95%, it exhibits the attractive NIR light shielding capability, which is in line with the predicted optical property via the first principle calculation based on density functional theory (DFT). Given the result, this work can provide a feasible research idea to explore the hidden optical properties of TB.