High reflectance tunable multi-color electrochromic films based on Fabry–Perot cavity

Currently, the difficulty of electrochromic use for full-color reflective display includes the color rendering range expansion and reflectance enhancement. The Fabry–Perot resonant cavity structure consisting of a broadband absorption layer allows high reflectivity spectral selection. It can actively modulate the optical response to a certain extent by implementing electrochemical control of the resonant cavity nanostructure. WO3 electrochromic layer was used as the dielectric layer of the broadband absorbing Fabry–Perot cavity, the transition metal Cr as the broadband absorbing layer material, and the inactive metal Al as the metal reflecting layer. The feasibility of the Al/WO3/Cr structure was analyzed theoretically, and the reflection spectrum of the designed electrochromic reflection display film was further investigated. The spectral colors of red, orange, yellow, green, blue, and violet can be obtained by adjusting the thickness of tungsten oxide. Moreover, the dynamic color control of the electrochromic device is achieved by electrically modulating the optical constants (n, k) of the WO3 film layer. The electrochromic device has the advantages of high brightness, high saturation, low cost, and low power consumption, providing a new option for designing full-color reflective displays in the future.