Electrochromism

About: Electrochromism is a research topic. Over the lifetime, 13097 publications have been published within this topic receiving 294637 citations.

Fast-switching photovoltachromic cells with tunable transmittance.

Abstract: In this study, we demonstrate a photovoltachromic cell (PVCC) which is a solar cell and able to take solar energy to stimulate chromic behavior with the characteristic of tunable transmittance. The cell is composed of a patterned WO(3)/Pt electrochromic electrode and a dye-sensitized TiO(2) nanoparticle photoanode. Compared to reported photoelectrochromic cells (PECC) with nonpatterned WO(3) electrochromic electrodes, PVCC achieves a much faster bleaching time of only 60 s by blocking the light at short circuit. When PVCC is bleached under illumination at open circuit, an exceedingly short bleaching time of 4 s is achieved. Furthermore, PVCC has photovoltaic characteristics comparable to those of dye-sensitized solar cells (with Pt as the counter-electrode). In contrast to conventional photochromic devices, the transmittance of PVCC under a constant illumination can be adjusted by the resistance of a load in series with the cell. These characteristics are a result of the patterned WO(3)/Pt electrode, which provides effective charge transfer pathways to facilitate the charging/discharging of Li ions and electrons via the photovoltaic potential and the Pt-electrolyte catalytic route, respectively.

Tunable electrochromic photonic crystals

Abstract: Photonic crystals based on the electrochromic phenomenon have been fabricated and proposed for band gap tuning. Electrochromic tungsten trioxide (WO3) inverse opals have been fabricated by polystyrene colloidal crystal templating. The WO3 matrix was obtained through a dip-infiltrating sol-gel process, with subsequent removal of the polymer microspheres by calcination. Scanning electron micrographs confirm the ordering of the hexagonal macroporous structure. The reflection spectra show two pronounced Bragg diffraction peaks. By inserting lithium into the crystals, the first reflection peak shifts gradually toward shorter wavelength for 36 nm, while the second reflection peak shifts toward longer wavelength for about 28 nm. This should be of great interest for photonic device applications.

Fabry-Perot Cavity-Type Electrochromic Supercapacitors with Exceptionally Versatile Color Tunability

Abstract: Electrochromic supercapacitors that can change their appearances according to their charged states are presently attracting significant interest from both academia and industry. Tungsten oxide is often used in electrochromic supercapacitors because it can serve as an active material for both benchmarking electrochromic devices and high-performance supercapacitor electrodes. Despite this, acceptable visual aesthetics in electrochromic supercapacitors have almost never been achieved using tungsten oxide, because, in its pure form, this compound only displays a 1-fold color modulation from transparent to blue. Herein, we defy this trend by reporting the first ever Fabry-Perot (F-P) cavity-type electrochromic supercapacitors based only on a tungsten oxide material. The devices were sensitively changeable according to their charge/discharge states and displayed a wide variety of fantastic patterns consisting of different, vivid colors, with both simple and complex designs being achieved. Our findings suggested a novel direction for the aesthetic design of intelligent, multifunctional electrochemical energy storage devices.

Superhydrophobic–Superoleophilic Polythiophene Films with Tunable Wetting and Electrochromism

Abstract: IO N There is much interest in superhydrophobic surfaces, as inspired by the non-wetting properties of the lotus leaf. [ 1 ] It can give a water contact angle greater than 150 ° with only 2–3% of the water droplet coming into contact with its surface, which is a common test for designating synthetic superhydrophobic surfaces. [ 1 ] The high water repellency is well worth mimicking because of the myriad industrial and practical applications, namely self-cleaning coatings, antifouling marine coatings, microfl uidics, antibiofouling, and anti-ice adhesion properties. [ 2 ] Here we report a novel and facile preparation of a nonfl uorinated superhydrophobic–superoleophilic polythiophene coating with reversibility to a superhydrophilic-and-oleophobic surface via electrochemical polymerization on a 2D layered colloidal particle template. Interestingly, such fi lms exhibit both simultaneous reversible electrochromic and extreme wettability properties by simply changing the voltage (potential) ex situ. Such a reversible wettability property can result in highly controlled wetting behavior with possible dual applications in self-cleaning coatings, channeling of fl ow properties, controlled membrane separations, and regenerable surfaces together with electro-optical functionality (electrochromic) by a mere switch of the applied potential. Artifi cial superhydrophobic surfaces can be accomplished by developing a dual-scale roughness structure and tuning of surface energy. [ 3 ] Most reports [ 2 , 3 ] have been on synthetic superhydrophobic surfaces fabricated using fl uorinated polymers and small molecule compounds, which are markedly known as low-surface-energy coating materials. [ 4 ] Fluorinated small molecule compounds in particular are more expensive and deemed to have some detrimental effects with bioaccumulation to the environment. [ 5 , 6 ] Therefore, these concerns necessitate the development of nonfl uorinated superhydrophobic coatings with other inherently useful functionality or properties. [ 7 , 8 ]