Ultra-low reflection CuO nanowire array in-situ grown on copper sheet

Abstract

Ultra-low reflectance materials are widely applied in the solar energy harvesting, the space instruments, spectrometers and terrestrial telescopes. The ultra-low reflection material of CuO/Cu in UV–vis is designed and achieved via orderly growing ultralong CuO nanowires on copper sheet, constructing the ultra-thick and vertically aligned array. The reflectance of the resultant samples range from 0.078% to 5.31%, via controlling the thickness and density of CuO nanowire arrays at different growth temperature and time. Among them, the blackest sample obtains an ultra-low reflectance of 0.078% in 200–700nm region and 0.0235% within the 500nm–600nm range. The ultra-low reflectivity of CuO nanowire arrays come from the following reasons: 1. the array is so thick and dense that the light can be multiply reflected and absorbed while propagates deep into the interspace of the nanowires, leading to an excellent light trapping. 2. The array can be regarded as air-filled gradient refractive index medium, which is also in favor of the low reflection. The CuO nanowire array represents a new-family of ultra-low reflection material in UV–vis. It will improve the sensitivity of optical instruments efficiently by blackening the inner-wall of drawtube or sample compartment for reducing stray light.