With the rapid development of optoelectronic fields, electrochromic (EC) materials and devices have received remarkable attention and have shown attractive potential for use in emerging wearable and portable electronics, electronic papers/billboards, see-through displays, and other new-generation displays, due to the advantages of low power consumption, easy viewing, flexibility, stretchability, etc. Despite continuous progress in related fields, determining how to make electrochromics truly meet the requirements of mature displays (e.g., ideal overall performance) has been a long-term problem. Therefore, the commercialization of relevant high-quality products is still in its infancy. In this review, we will focus on the progress in emerging EC materials and devices for potential displays, including two mainstream EC display prototypes (segmented displays and pixel displays) and their commercial applications. Among these topics, the related materials/devices, EC performance, construction approaches, and processing techniques are comprehensively disscussed and reviewed. We also outline the current barriers with possible solutions and discuss the future of this field.

As future energy-saving optoelectronics, bistable electrochromic (EC) materials/devices have high energy efficiency for potential applications as smart window, display and information/energy storage, etc., due to the ability of maintaining optical states without energy consumption. However, further development is hindered for the lack of in-depth understanding of related key factors and universally applicable design strategies for bistability. Herein, we reported a new strategy based on "active energy-exchange" with aid of proton coupled electron transfer, which can dynamically adjust the HOMO/LUMO energy levels of materials to obtain good bistability from traditional non-bistable materials. This strategy was thoroughly studied and proved by taking quinone derivatives and bromocresol green derivatives as examples. The device obtained after further polymerization and optimization showed remarkable bistability, coloration efficiency and application potential in energy-saving flexible displays. The success, challenges and cognitive gains of this strategy not only accelerate the development of various energy-saving optoelectronic materials/devices, but also likely stimulate rapid progress of physics, chemistry, life sciences, applied mathematics, precision instruments, etc.