Photonic Multilayer Structure Induced High Near‐Infrared (NIR) Blockage as Energy‐Saving Window

Abstract

Energy‐saving window that selectively blocks near‐infrared (NIR) is a promising technology to save energy consumption. However, it is hard to achieve both high transmittance in visible light and high reflectance in NIR for the energy‐saving windows. Here, a TiO2/Ag/TiO2/SiO2/TiO2 multilayer is demonstrated on a glass substrate to selectively block NIR while maintaining high transmittance to visible light. The thickness of a TiO2/Ag/TiO2 structure is first design and optimized; the metal layer reflects NIR and the dielectric layers increase transmittance of visible light with zero reflection condition. To further enhance NIR‐blocking capability, a TiO2 back reflector is implemented with a SiO2 spacer to TiO2/Ag/TiO2 structure. The back reflector can induce additional Fresnel reflection without sacrificing transmittance to visible light. The optimal TiO2 (32 nm)/Ag (22 nm)/TiO2 (30 nm)/SiO2 (100 nm)/TiO2 (110 nm)/glass shows solar energy rejection 89.2% (reflection 86.5%, absorption 2.7%) in NIR, visible transmittance 69.9% and high long‐wave (3 ≤ λ ≤ 20 µm) reflectance > 95%. This proposed visible‐transparent, near‐infrared‐reflecting multilayer film can be applied to the windows of buildings and automobiles to reduce the energy consumption.

The Potential of Static and Thermochromic Window Films for Energy Efficient Building Renovations

“…Window films can be fabricated via roll-to-roll methods on flexible substrates at high throughput. Over the years, companies in this field, such as 3M and Saint-Gobain, developed a variety of window films having various gradations of tinting and near-IR reflection based on reflective metal-containing coatings or absorptive metal oxides (Jelle et al, 2015;Kim et al, 2021). These films are designed and optimized for various climates around the world.…”

A Facile Strategy to Realize Rapid and Heavily Hydrogen-Doped VO2 and Study of Hydrogen Ion Diffusion Behavior

“…As a typical strongly correlated material, vanadium dioxide (VO 2 ) experiences first-order insulator–metal transition and structural transformation, accompanying apparent infrared switching from a high transmittance state to a low transmittance state. These advanced features make VO 2 a promising candidate for “smart windows”, − memory devices, − and photoelectric detection. − The 3d 1 electronic configuration of VO 2 suggests a metallic state, while electron–electron correlation and V–V dimerization contribute together to the formation of the insulating state. Therefore, the electronic and crystal structures of VO 2 are closely associated with the charge doping.…”

Photonic response and temperature evolution of SiO2/TiO2 multilayers

“…Both SiO 2 and TiO 2 have high melting points (1710 °C and 1843 °C, respectively [11]) and experiments with post-annealed powder mixtures of them have proved that the materials are immiscible in solid state and have limited mutual solubility in liquid state [12,13]. As a result, they constitute an attractive material couple for high-temperature photonic applications [14], particularly in solar technology [15][16][17], and have been prepared using different fabrication conditions and methods [18,19]. At elevated temperature conditions, thermal energy alters the microstructure of each material (phase, density, grain size, etc.…”