Transparent Electrochemical Gratings from a Patterned Bistable Silver Mirror

Synergistic Electric and Thermal Effects of Electrochromic Devices

Electrochromic devices are the preferred devices for smart windows because they work independently of uncontrollable environmental factors and rely more on the user's personal feelings to adjust actively. However, in practical applications, the ambient temperature still has an impact on device performance, such as durability, reversibility and switching performance, etc. These technical issues have significantly slowed down the commercialization of electrochromic devices (ECDs). It is necessary to investigate the main reasons for the influence of temperature on the device and make reasonable optimization to enhance the effectiveness of the device and extend its lifetime. In recent years, with the joint efforts of various outstanding research teams, the performance of electrochromic devices has been rapidly improved, with a longer lifetime, richer colors, and better color contrast. This review highlights the important research on temperature-dependent electrochromic properties in recent years. Also, the reported structures, mechanisms, characteristics, and methods for improving electrochromic properties are discussed in detail. In addition, the challenges and corresponding strategies in this field are presented in this paper. This paper will inspire more researchers to enrich the temperature-dependent properties of ECDs and their related fields with innovative means and methods to overcome the technical obstacles faced.

A Superhydrophobic, Antibacterial, and Durable Surface of Poplar Wood

The silver particles were grown in situ on the surface of wood by the silver mirror method and modified with stearic acid to acquire a surface with superhydrophobic and antibacterial properties. Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), and X-ray energy spectroscopy (XPS) were used to analyze the reaction mechanism of the modification process. Scanning electron microscopy (SEM) and contact angle tests were used to characterize the wettability and surface morphology. A coating with a micro rough structure was successfully constructed by the modification of stearic acid, which imparted superhydrophobicity and antibacterial activity to poplar wood. The stability tests were performed to discuss the stability of its hydrophobic performance. The results showed that it has good mechanical properties, acid and alkali resistance, and UV stability. The durability tests demonstrated that the coating has the function of water resistance and fouling resistance and can maintain the stability of its hydrophobic properties under different temperatures of heat treatment.

A Quasi-Solid-State Tristate Reversible Electrochemical Mirror Device with Enhanced Stability

Reversible electrochemical mirror (REM) electrochromic devices with electrochemical tunability in multiple optical states are exciting alternatives to conventional electrochromic smart windows. Electrochromic devices are studied extensively, yet widespread adoptions have not been achieved due to problems associated with durability, switching speed, limited options on optical states, and cost. In this study, a REM electrochromic device based on CuSn alloy is developed, which offers highly reversible switching between transparent, greyish-blue, and mirror states via reversible electrodeposition and dissolution. The alloying element, Sn acts as an electrochemical mediator, which facilitates the electrodeposition and dissolution of Cu. The CuSn-based REM device shows superior cycling stability for 2400 cycles (transmittance mode) and 1000 cycles (reflectance mode). The electrodeposited CuSn alloy film is resistant to surface oxidation in ambient air, with a 2.9% difference in reflectance at 2000 nm after 3 days. In addition, the alloy film exhibits excellent NIR reflectance property with thermal modulation of 18.5 °C at a high temperature of 180 °C. The REM device with zero power consumption maintains its mirror state for at least 100 min, making it a promising candidate for energy-efficient applications.

Poly(ionic liquid) Electrolytes for a Switchable Silver Mirror

Imidazolium-type small-molecule ionic liquids (ILs) and their corresponding poly(ionic liquid) (PIL) homopolymers were synthesized and applied to reversible electrochemical mirrors (REMs). The effects of alkyl chain length of the carbon chains at the N3 position and cation charge density (mono- and bis-imidazolium) on the electrochromic properties of Ag-based REMs were investigated by analyzing their electrodeposition and spectral properties. Longer alkyl chains and higher charge densities decreased the size and resulted in a more uniform distribution of Ag nanoparticles. Compared with IL-based liquid electrolytes, the PIL-based gel electrolytes formed smaller and denser electrodeposited metallic Ag nanoparticles because of their higher viscosity. These findings were used to guide fabrication of a 50 cm² mirror dynamic window and flexible display. Because of several unique properties of PILs, the PIL-based REM exhibits fast switching speeds, superb cycling durability, small particle sizes, and uniform electrodeposited Ag nanoparticle films. These results make dynamic windows based on PIL electrolytes promising and competitive alternatives to traditional electrochromic windows.