Electrochromic polymers (ECPs) have great application potential in flexible displays, and there is an increasing expectation of using green methods to form ECP films. Herein, we propose a modified microemulsion method to prepare Cyan/Magenta/Yellow (C/M/Y) water-dispersed electrochromic polymer nanoparticles systems. Three polymer films (WDECP-C/M/Y) maintain similar electrochemical properties compared to their corresponding organic solvent-based polymer films. It is intriguing that WDECP-C/M/Y exhibit better electrochromic properties in terms of higher cycling stability (97.24%, 95.05%, and 52.84%, respectively) and faster switching time (0.94 s, 1.09 s, and 1.34 s for coloring time, respectively) due to the introduction of nanoparticles. In addition, it can achieve various desired colors by blending the C/M/Y water-dispersed electrochromic polymer nanoparticles systems in different ratios. The calculated chromaticity coordinates of the blending polymer films show close values to the experimental observation, and the calculated ΔE*ab values range from 2.6 to 10.3, which may provide theoretical guidance for precisely color control. Finally, large-scale and patterned devices were assembled, which can achieve colored-to-colorless reversible electrochromism at a low driving voltage of 0 to 1.5 V. This work puts forward a universal and environmentally sustainable strategy to prepare water-dispersed electrochromic polymer nanoparticles systems, demonstrating their wide range of applications in display devices and electronic tags.
The systematic study of two ionic porous organic polymers (iPOPs) based on viologens and their first applications in the electrochromic field are reported. The viologen-based iPOPs are synthesized by electrochemical polymerization with cyano groups, providing a simple and controllable method for iPOPs that solves the film preparation problems common to viologens. After the characterization of these iPOPs, a detailed study of their electrochromic properties is conducted. The iPOP films based on viologens structure exhibit excellent electrochromic properties. In addition, the resulting iPOP films show high sensitivity to electrolyte ions of different sizes in the redox process. Electrochemical and electrochromic data of the iPOPs explain this phenomenon in detail. These results demonstrate that iPOPs of this type are ideal candidates as electrochromic materials due to their inherent porous structures and ion-rich properties.
The integration of an electrochromic (EC), energy storage, and adaptive camouflage system into a multifunctional electronic device is highly desirable and yet challenging. In this work, two carbazole-based conjugated polymers were prepared to achieve a reversible color change from transparent to yellow, green, and blue-green by easy electrochemical polymerization. Due to its dendritic geometry, the conjugated polymer p3CBCB exhibits a loosely packed structure with a relatively higher specific surface area than pCBCB, as well as a relatively better ionic conductivity. The kinetic and galvanostatic charge-discharge (GCD) study reveals that p3CBCB has superior properties with larger optical contrast and volumetric capacitance. Moreover, EC supercapacitors (ECSCs) are constructed with p3CBCB as the EC layer and ZnO@PEDOT:PSS as the ion storage layer. The dual function of a ZnO interface layer on improvement in reflectivity contrast (ΔR% > 35.1%) and cycling stability (over 40,000 cycles) using ZnO as a reflective and protective layer is demonstrated in an ion storage layer. Additionally, patterned prototype devices based on the design of double-sided ITO glass were successfully assembled, which can simulate conditions of various natural environments including forests, wilderness, and deserts. This study provides new ideas not only for the preparation of conjugated polymers that can simultaneously realize reversible transparent-yellow-green conversion but also for the achievement of high coloration efficiency, high reflectivity contrast, and good stability of ECSCs for adaptive camouflage.
This work presents a new strategy to achieve a truly black electrochromic film and develop available intelligent eye-protection filters with "day mode" and "night mode", promising to minimize the harmful effects of light on eyes. The soluble red-to-transparent electrochromic polymer P1 was constructed using quinacridone as the basic unit and introduced dual-donor proDOT and DTC units with similar electron-donating capabilities. The beneficial broader absorption associated with the dual-donor in P1 results in ideal spectrum complementarity with P2 (cyan-to-transparent) in the visible region (380-780 nm). In addition to complementary colors, both polymers exhibit good compatibility with respect to electrochemical and electrochromic properties. Therefore, a P1/P2 film with a mass ratio of 1:1.5 for blending is preferred to obtain truly black color with fast switching time and good cyclic stability. Furthermore, an electrochromic device for intelligent eye-protection filters was designed and assembled with the P1/P2 film as the electrochromic layer and P3 featuring a yellow (antiblue ray)-to-dark gray color change as the ion storage layer. The assembled prototype electrochromic device demonstrated promising applications in intelligent day-night optical adjustment for eye-protection filters.
