Tungsten Trioxide（WO3）is an electrochromic semiconductor material with early discovery, study and application widely. It has good chemical stability, no toxicity, great difference in optical properties between coloring and fading, and long cycle life, so it has been widely used in the field of energy conservation.
Electrochromism is a phenomenon where the optical properties of materials (reflectivity, transmittance, absorption rate, etc.) undergo stable and reversible color changes under the action of an applied electric field, which is manifested as reversible color changes and transparent appearance. For example, when Tungsten Trioxide is used in electrochromism, its electrons are transferred under the stimulation of photovoltage, causing the valence state of W atoms to change between w 6+ ion and w 5+ ion. Macroscopically, the color of Tungsten Trioxide changed from slight yellow to deep blue.
Materials with electrochromic properties are called electrochromic materials and devices made of them are called electrochromic devices. Tungsten Trioxide is a typical and common electrochromic semiconductor material, which has good electrochromic performance and low preparation cost. However, the earliest discovered and widely studied electrochromic material is the amorphous Tungsten Trioxide thin film, which has the advantages of recycling, obvious discoloration, long storage time and high stability, and can be widely used in intelligent windows and display devices in the fields of automobile, aerospace and so on.
Glasses containing Tungsten Trioxide have electrochromic properties, which can effectively isolate ultraviolet rays and lower indoor temperatures in summer. Different from glass made of other materials, it only needs to consume electricity in state transition, thereby reducing the cost of air conditioning and saving energy. In the battery, the addition of Tungsten Trioxide can reduce the potential of partial pressure and sharp temperature rise, and improve the specific capacity and thermal stability of the product.
