文摘
We introduce a new type of ZnO array structure that can effectively suppress the reflection of light at a range of wavelength from ultraviolet through visible part to the near-infrared region, with reflectivity <2.5%, resulting in its black color. This black ZnO is composed of a random pyramidal array growing directly on Zn foil through a simple hydrothermal method. We have investigated the causes of antireflection by removing the pyramid tips via scratching and ion etching on the ZnO surface. All results demonstrate that the antireflection nature of the black ZnO originates from the pyramidal array structure, which causes a gradient change of refractive index between air and substrate.