Novel Bistable Electrochromic Devices Inspired by “Hydroxyl‐Acids”

Abstract The development of bistable electrochromic materials is a promising way to reduce the energy consumption of displays. However, bistable devices with ideal implementation schemes and electrochromic performance still remain challenging due to the inherent limitations of existing electrochromic materials. Herein, a theory of “hydroxyl‐acids” assisted improvement of electrochromic rate and bistability of fluorane dyes is proposed and applied to solid‐state electrochromic devices. 80% hydroxypropyl acrylate‐20% methyl methacrylate copolymer‐based electrochromic film prepared by the theory of “hydroxyl‐acids” has a higher electrochromic rate (4.1 times) and bistability (5.4 times) than traditional PMMA‐based electrochromic films in the device. In addition, the optimum device is obtained by optimizing each layer component content of the device. The novel electrochromic device has good overall performance, including coloring time (7.5 s), transmittance change (>70%), coloration efficiency (872 cm 2 C ‐1 ), bistability (50 h), and reversibility (1,000 cycles). The theory of “hydroxyl‐acids” is suitable for a variety of fluorane dyes, and polychromatic bistable electrochromic windows are developed.