Enhanced Efficiency of Functional Smart Window with Solar Wavelength Conversion Phosphor–Photochromic Hybrid Film

[Image: see text] Here, the high sensitivity and enhanced photochromic efficiency of the hybrid film of solar wavelength conversion phosphor and photochromic film for functional smart window have been achieved by fabricating a double-layered hybrid structure of wavelength conversion phosphor and photochromic film. Y(2)SiO(5):Pr(3+) phosphor nanoparticles, which upconvert visible light to UV light, were synthesized by simple hydrothermal method. The synthesized Y(2)SiO(5):Pr(3+) nanoparticle was coated as layered structured film on photochromic H(3)PW(12)O(40) film. The Y(2)SiO(5):Pr(3+)/H(3)PW(12)O(40) hybrid film showed an enhanced sensitivity and efficiency of photochromic process with solar light irradiation due to the increased UV portion of solar light through upconversion process of visible light by wavelength conversion phosphor layer. The increased UV portion by upconversion process of Y(2)SiO(5):Pr(3+) layer through excited-state absorption and energy transfer upconversion process, contributed to an enhancement of coloration rate of photochromic H(3)PW(12)O(40) film by 7 times with 50 min of 1 sun irradiation due to fast conversion of W(6+) state to W(5+) state in H(3)PW(12)O(40) film with 5 times enhanced photochromic sensitivity compared with pristine photochromic film.