Transparent-to-dark photo- and electrochromic gels

Abstract

Smart windows in which the transmittance can be controlled on demand are a promising solution for the reduction of energy use in buildings. Windows are often the most energy inefficient part of a building, and so controlling the transmittance has the potential to significantly improve heating costs. Whilst numerous approaches exist, many suitable materials are costly to manufacture and process and so new materials could have a significant impact. Here we describe a gel-based device which is both photo-and electrochromic. The gel matrix is formed by the self-assembly of a naphthalene diimide. The radical anion of the naphthalene diimide can be formed photo or electrochemically, and leads to a desirable transition from transparent to black. The speed of response, low potential needed to generate the radical anion, cyclability of the system, temperature stability and low cost mean these devices may be suitable for applications in smart windows.

Flower‐Like Morphology of Naphthalene Diimides Containing tetra‐L‐ and D‐Alanine

“…The different aromatic as well as aliphatic molecules such as pyrene, perylene diimides, tetraphenylethylene, diketopyrrolopyrrole, D-xyloside, L-rhamnose are utilized for the fabrication of nanostructures via selfassembly. [17À 19] It is well known that naphthalene diimides (NDIs) [20] are widely used building blocks for the fabrication of different nanostructures such as nanofibers, [21] nanotubes, [22] nanoflowers [23] and chiral materials. [24] NDIs are π-conjugated planar aromatic compound exhibiting n-type semiconducting properties and are employed in OFETs, [25] OLEDs [26] and solar cell [27] applications.…”

Stimuli responsive dynamic transformations in supramolecular gels

“…17). 195 When this gel was exposed to sunlight or irradiated by 365 nm light, the gel darken due to the formation of the radical anion. Generation of NDI-radical anions that turned the transparent gel into black could also be achieved electrochemically.…”

Switchable Cavitation in Silicone Coatings for Energy‐Saving Cooling and Heating

“…[3,4] To decrease the impact of indoor heating and cooling on the environment, environmentally friendly and energy-saving alternatives are urgently needed. To date, several alternative technologies combining adaptive heating and cooling in one system have been developed, including smart windows, [5][6][7][8][9][10][11][12][13][14] Janus membranes, [15,16] and solar chimneys commercially available poly(dimethylsiloxane) (PDMS) precursor followed by curing in air ( Figure S1, Supporting Information). Similar to normal PDMS precursors, the emulsion needs about 6 days at room temperature to get fully cured, but could solidify within the first 20 min, accompanied by the fixation of the embedded water droplets.…”