In the Ta doped tungsten oxide electrochromic film, the amount of Ta doping affects the spectral modulation ability of the tungsten oxide film. The optical modulation amplitude ΔT of the tungsten oxide film is the difference of transmittance between the colored state and the discolored state.
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Experts show that the optical modulation amplitude of the tungsten oxide film after Ta doping is slightly decreased. The ΔT is almost unchanged in the range of 5%-15% of Ta doping amount, which is equivalent to the optical modulation amplitude of the pure WO3 film. However, when the doping amount continues to increase to 25%, or up to 30%, the ΔT decreases significantly. It can be seen that the doping amount of Ta needs to be controlled within a certain range, and excessive doping may affect the optical modulation performance of the tungsten oxide film. The reason may be that WO3 has more excellent electrochromic performance than Ta2O5, and excessive Ta doping may cause a significant decrease in WO3 content in the Ta-doped tungsten oxide electrochromic film, thereby adversely affecting its spectral modulation ability.
