Scalable Photochromic Film for Solar Heat and Daylight Management

Abstract

The adaptive control of sunlight through photochromic smart windows could have a huge impact on the energy efficiency and daylight comfort in buildings. However, the fabrication of inorganic nanoparticle and polymer composite photochromic films with a high contrast ratio and high transparency/low haze remains a challenge. Here, a solution method is presented for the in situ growth of copper‐doped tungsten trioxide nanoparticles in polymethyl methacrylate, which allows a low‐cost preparation of photochromic films with a high luminous transparency (luminous transmittance Tlum = 91%) and scalability (30 × 350 cm2). High modulation of visible light (ΔTlum = 73%) and solar heat (modulation of solar transmittance ΔTsol = 73%, modulation of solar heat gain coefficient ΔSHGC = 0.5) of the film improves the indoor daylight comfort and energy efficiency. Simulation results show that low‐e windows with the photochromic film applied can greatly enhance the energy efficiency and daylight comfort. This photochromic film presents an attractive strategy for achieving more energy‐efficient buildings and carbon neutrality to combat global climate change.

Chelating Coordination Regulated Photochromic Electrospun Nanofibers for Waterproof and Long-Color-Retention Rewritable Wearables

“…This duration exceeds that described in most published literature about WO 3 -based photochromic materials (Table S2). ,,− When the amount of chelator was changed, the color retention times of PWE 2 and PWE 1 were about 5–7 and 3–5 days, respectively. However, PW without EDTA decolorized entirely in 1–3 days under the same environmental conditions (Figure S4c, SI).…”

Inorganic photochromic materials: Recent advances, mechanism, and emerging applications

“…Furthermore, high modulation of visible light (ΔT lum = 73%) and solar heat (modulation of solar transmittance ΔT sol = 73%) of the photochromic film facilitates the indoor daylight comfort and energy efficiency. [7] Such all-solid, free-standing flexible photochromic film based smart windows present an attractive strategy for achieving more energy-efficient buildings, improving indoor daylight comfort and beyond. It is expected more fundamental research could be conducted to enrich this library of photochromic compounds to fully fulfill the requirement of on-demand smart windows.…”

“…Responsive materials showing reversible color change upon external stimuli have attracted extensive attention because of their technological applications in sensors, energy, decoration, bio-imaging, catalysis, and so on. [1][2][3][4][5][6][7][8][9][10] Typically, the color change can be triggered by various stimuli such as thermal, [11,12] stress, [13,14] light, [15,16] electricity, [17] magnetism, [18] and nuclear radiation. [19] When the external stimulus is light, this phenomenon is known as photochromism.…”

Visible-Light-Responsive Photoreversible Color Switching of Oxygen-Deficient WO3–x Hierarchical Nanostructures for Long-Legible Rewritable Paper

“…Photoreversible color switching materials (PCSMs) that can reversibly change color under light stimulation have attracted increasing attention because of their potential applications in anticounterfeiting, 1−3 optical recording, 4−6 color displays, 7−15 smart windows, 16 and sensors. 17,18 Specifically, PCSMs are successfully demonstrated for the application in ink-free lightprintable rewritable paper (LPRP), which has potential environmental benefits including forest conservation, pollution reduction, and resource sustainability compared with current paper printing.…”

“…Photoreversible color switching materials (PCSMs) that can reversibly change color under light stimulation have attracted increasing attention because of their potential applications in anticounterfeiting, − optical recording, − color displays, − smart windows, and sensors. , Specifically, PCSMs are successfully demonstrated for the application in ink-free light-printable rewritable paper (LPRP), which has potential environmental benefits including forest conservation, pollution reduction, and resource sustainability compared with current paper printing. − Great advances have been achieved in the development of photochromic molecules (e.g., azobenzenes, spiropyrans, diarylethenes, etc.) with impressive photoreversible color switching properties. − However, their practical applications are still impeded by several challenges, such as gradual molecular degradation under sustained UV light exposure and the use of toxic synthetic precursors.…”