Luminescent Antireflective Coatings with Disordered Surface Nanostructures Fabricated by Liquid Processes

作者：Tanaka Sota; Fujihara Shinobu^*

来源：Langmuir, 2011, 27(6): 2929-2935.

DOI：10.1021/la200149y

Antireflective phosphor coatings having disordered surface nanostructures were fabricated by a sol gel dip coating method and a subsequent hot water treatment. Thin films of a Bi(3+),Eu(3+)-codoped YVO(4) red phosphor were first prepared and effects of the addition of an aluminum source to precursor solutions on their microstructure and optical properties were examined. Optical transmittance of the YVO(4):Bi(3+)Eu(3+) film was lower than that of a bare quartz glass substrate due to a higher refractive index of YVO(4). The addition of the aluminum source and the hot water treatment resulted in a considerable increase of transmittance and its smaller angular dependence, which could generate an antireflective effect by the phosphor thin films. Observation of the microstructure revealed that the hot water treatment brought a remarkable change in the surface as well as the cross-section structure in the aluminum-added YVO(4):Bi(3+)Eu(3+) film. The film density and hence the refractive index were gradually changed like a pseudo moth-eye structure, which explained the occurrence of the antireflective effect. The microstructural change was attributed to the dissolution of alumina present in the film and the reprecipitation of boehmite on the film surface during the hot water treatment. Photoluminescence of the YVO(4):Bi(3+)Eu(3+) film could also be enhanced by the antireflective effect due to the suppression of surface Fresnel reflection of incident light and total internal reflection of emitted light.

• 出版日期2011-3-15