Effect of annealing treatment on optical properties of structural color films

Structural color materials based on periodic micro and nano structures present unique color rendering mechanism and optical properties, and have a wide range of applications in display, packaging, sensing and other fields. However, it is still facing the problems of constructing large area, good consistency and low cost periodic structures. In this paper, the structural color film was prepared by annealing treatment on a periodic template. The effects of coating time, annealing time and annealing process on the optical properties of the sample such as hue and saturation were analyzed. It was confirmed that the sample with 300 nm polystyrene microsphere template presented orange yellow with incident angle of 30 degrees before annealing, then turned to be light pink under 800 degrees C for 120 min annealing process and orange red under 800 degrees C for 180 min in air. Additionally, the sample with 420 nm polystyrene microsphere template showed cyan before annealing, and yellow-green under 800 degrees C for 120 min annealing treatment and orange-yellow under 800 degrees C for 180 min. The periodicity of the annealed gold microspheres was still limited by the template period with different diameters. Morever, when the coating and annealing time were the same, the higher the annealing temperature was, the higher the saturation get. Under the same coating time and annealing temperature, the saturation was higher with short annealing time, and the hue blue-shifted as the incident angle increased from 15 degrees to 45 degrees. While fixing the annealing time and temperature, the saturation increased gradually as the coating time increasing from 10S to 40S, and the color of the sample red-shifted.