High-quality ZnO anti-reflective coatings for CdSe crystal in the infrared wavelength

The anti-reflective coating of infrared window materials plays an important role in infrared devices. In this paper, pure ZnO nanoparticles dispersion liquid was obtained by purifying and redispersing ZnO nanoparticles of about 4 nm prepared by the sol-gel method. High-performance ZnO coatings were prepared on CdSe crystals by the dip-coating method. Changing the thickness of the ZnO coating can change the position of the optimal anti-reflection. In the wavelength range of 1280-3000 nm, the lowest reflectance can reach 0.20 %, and the average reflectance is reduced from 26.36 % to 6.02 %. In the wavelength range of 3000-5000 nm, the lowest reflectance can reach 0.22 %, and the average reflectance is reduced from 26.91 % to 2.23 %. In the wavelength range of 8000-10,000 nm, the lowest reflectance can reach 0.20 %, and the average reflectance is reduced from 28.24 % to 1.28 %. Especially in the wavelength ranges of 3000-5000 and 8000-10,000 nm, the anti-reflection is significant in the whole band. In addition, the coating has excellent high-temperature stability and mechanical properties. This work is of great significance for preparing infrared anti-reflection coatings by chemical method.