Antireflection characteristics of inverted nanopyramid arrays fabricated by low-cost nanosphere lithography technology

A simple and effective process based on nanosphere lithography for the fabrication of periodic inverted nanopyramid structure is presented in this article. The prepared nanostructure has almost a drop of 40% in the average reflectance at normal incidence, when compared with its corresponding bare silicon surface. Moreover, we obtained the reflection spectra for bare silicon substrate and prepared nanostructure through experiments and numerical calculations, and the results agreed well with each other, respectively. Therefore, we can combine the simulation method and fabrication method together to optimize the nanostructured antireflection coatings for better antireflection characteristics, and this methodology is robust and promising for the development of crystalline silicon solar cells. We further discussed the influences of pyramid size and the lattice constant of the nanopyramid array on the antireflection effect by numerical calculation, and we got a conclusion that the antireflection effect is positively correlated with the area-ratio defined as the ratio of the sum of the area of the nanopyramid holes in a unit cell to the area of a unit cell. Finally, we provide some direction and help for other researchers about the antireflection application of inverted nanopyramid arrays.