Three‐Layered Hollow Nanospheres Based Coatings with Ultrahigh‐Performance of Energy‐Saving, Antireflection, and Self‐Cleaning for Smart Windows

Abstract

In this study, a well-controlled interfacial engineering method for the synthesis of SiO /TiO /VO three-layered hollow nanospheres (TLHNs) and TLHNs-based multifunctional coatings is reported. The as-prepared coatings allow for an outstanding integration of thermochromism from the outer VO (M) layer, photocatalytic self-cleaning capability from the middle TiO (A) layer, and antireflective property from internal SiO HNs. The TLHNs coatings exhibit excellent optical performance with ultrahigh luminous transmittance (T = 74%) and an improved solar modulation ability (ΔT = 12%). To the best knowledge, this integrated optical performance is the highest ever reported for TiO /VO -based thermochromic coatings. An ingenious computation model is proposed, which allows the n of nanostructured coatings to be rapidly obtained. The experimental and calculated results reveal that the unique three-layered structure significantly reduces the refractive index (from 2.25 to 1.33 at 600 nm) and reflectance (Rave, from 22.3 to 5.3%) in the visible region as compared with dense coatings. Infrared thermal imaging characterization and self-cleaning tests provide valid evidence of SiO /TiO /VO TLHNs coatings' potential for energy-saving and self-cleaning smart windows. The exciting inexpensive and universal fabrication process for well-defined structures may inspire various developments in processable and multifunctional devices.

Effect of Mie Scattering on Thermochromic Performance of Branched VO2 Prepared by One‐Step Hydrothermal Method

“…To evaluate the thermochromic performance of VO 2 films, an integral luminous transmittance ( T lum , 380–780 nm) and solar transmittance ( T sol , 250–2500 nm) are respective calculated based on the measured UV/Vis‐IR spectra utilizing the following formula: where T(λ) represents the transmittance at wavelength λ , while φ lum is the standard luminous efficiency function for the photopic vision of human eyes, φ sol denote the solar irradiance spectrum for the air mass 1.5 (corresponding to the sun standing 37° over the horizon). The solar energy modulation (Δ T sol ) is defined as the difference of T sol between the semiconducting state and the metallic state of VO 2 .…”

Multi‐stimuli‐responsive and Multi‐functional Smart Windows

“…It is also known that continuous VO 2 films have a low T lum and Δ T sol ; [3,18] therefore, various synthetic and fabrication methods, under optimal thickness, have been developed to improve the thermochromic performance of these films [80–90] . Anti‐reflection properties have been induced by either coating VO 2 films with various compounds (e. g., TiO 2 , ZrO 2 , SiO 2 , CeO 2 , FTO, and AZO) or by constructing structured VO 2 (nanoparticles, porous films, and various patterned structures) [91–101] . VO 2 nanocomposites films have also been prepared to lower the transition temperature and achieve a higher T lum and Δ T sol [102–105] …”

Review: smart windows based on photonic crystals

“…Energy-saving glass that has been developed and applied includes insulating glass [10][11][12], coated glass [13][14][15] and metallized glass [16][17][18]. However, solar energy can only be statically adjusted due to its fixed lighting and heating performance, which has great limitations in energy utilization.…”