Durability-enhanced vanadium dioxide thermochromic film for smart windows

Transparent wood is considered a promising structural and light management material for energy-efficient engineering applications. However, the solution-based delignification process that is used to fabricate transparent wood generally consumes large amounts of chemicals and energy. Here, we report a method to produce optically transparent wood by modifying the wood’s lignin structure using a solar-assisted chemical brushing approach. This method preserves most of the lignin to act as a binder, providing a robust wood scaffold for polymer infiltration while greatly reducing the chemical and energy consumption as well as processing time. The obtained transparent wood (~1 mm in thickness) demonstrates a high transmittance (>90%), high haze (>60%), and excellent light-guiding effect over visible wavelength. Furthermore, we can achieve diverse patterns directly on wood surfaces using this approach, which endows transparent wood with excellent patternability. Combining its efficient, patternable, and scalable production, this transparent wood is a promising candidate for applications in energy-efficient buildings.

show abstract

“…American balsa wood with the density of 0.15 to 0.26 g/cm 3 was purchased from Specialized Balsa Wood LLC. Sodium hydroxide…”

Section: Materials and Chemicalsmentioning

confidence: 99%

“…where V f is the volume fraction of lignin-modified wood,  c is the density of composite,  m is the density of epoxy (1.09 g/cm 3 ),  f is the density of lignin-modified wood (~0.2 g/cm 3 ), W f is the weight fraction of lignin-modified wood, and W m is the weight fraction of the epoxy.…”

Section: The Volume Fraction Of Lignin-modified Woodmentioning

confidence: 99%

Solar-assisted fabrication of large-scale, patternable transparent wood

et al. 2021

View full text Add to dashboard Cite

show abstract

“…Moreover, other authors have researched the use of different matrices to improve the lifespan of vanadium dioxide (VO 2 ) nanoparticles. For example, the highly entangled and crosslinked poly (methyl methacrylate) (PMMA) showed a promising pathway toward creating environmentally stable and easily scalable thermochromic films [36]. More recently, the VO 2 was doped with tin (Sn), enhancing its visible transmittance and providing the films with excellent thermochromic properties [37].…”

Section: Optical Modulation Of Passive Daytime Radiative Coolingmentioning

confidence: 99%

Optically Modulated Passive Broadband Daytime Radiative Cooling Materials Can Cool Cities in Summer and Heat Cities in Winter

et al. 2022

View full text Add to dashboard Cite

Broadband passive daytime radiative cooling (PDRC) materials exhibit sub-ambient surface temperatures and contribute highly to mitigating extreme urban heat during the warm period. However, their application may cause undesired overcooling problems in winter. This study aims to assess, on a city scale, different solutions to overcome the winter overcooling penalty derived from using PDRC materials. Furthermore, a mesoscale urban modeling system assesses the potential of the optical modulation of reflectance (ρ) and emissivity (ε) to reduce, minimize, or reverse the overcooling penalty. The alteration of heat flux components, air temperature modification, ground and roof surface temperature, and the urban canopy temperature are assessed. The maximum decrease of the winter ambient temperature using standard PDRC materials is 1.1 °C and 0.8 °C for daytime and nighttime, respectively, while the ρ+ε-modulation can increase the ambient temperature up to 0.4 °C and 1.4 °C, respectively, compared to the use of conventional materials. Compared with the control case, the maximum decrease of net radiation inflow occurred at the peak hour, reducing by 192.7 Wm−2 for the PDRC materials, 5.4 Wm−2 for ρ-modulated PDRC materials, and 173.7 Wm−2 for ε-PDRC materials; nevertheless, the ρ+ε-modulated PDRC materials increased the maximum net radiation inflow by 51.5 Wm−2, leading to heating of the cities during the winter.

show abstract

“…The transition temperature can be controlled through doping with tungsten (W), with higher ratios of W to VO 2 bringing it down as low as room temperature (25 °C), whereas doping with hydrogen ( H ) can control the transmissivity. [ 67,68 ] The IMT brings on changes of the optical properties that are reversible with a long lifetime, as long as the VO 2 can be protected from oxygenation to prevent the formation of V 2 O 5 , [ 69–71 ] and can be induced both thermally [ 62,72 ] and electrically. [ 73 ] These properties, alongside its volatile IMT, make VO 2 an attractive material for use in passively adaptive metamaterials and nanophotonic devices.…”

Section: Switchable Metasurfacesmentioning

confidence: 99%

Tunable Metasurfaces: The Path to Fully Active Nanophotonics

Badloe

Lee

Seong

et al. 2021

Advanced Photonics Research

View full text Add to dashboard Cite

In the field of nanophotonics, metasurfaces have come to the forefront in real‐world applications, owing to their accessible exotic optical properties that can be readily designed and fabricated using currently available techniques. The subwavelength dimensions and lightweight characteristics of metasurfaces are attractive qualities for the miniaturization of optical devices and are already exploited in devices that can rival, and sometimes even outperform, conventional bulky optics. Over the past decade, ample research has been undertaken to produce high‐performance metasurfaces with exciting optical properties that cannot be found in nature or achieved with conventional optics. To open the path to widely used devices in our everyday lives, the next obvious step for metasurfaces is the development of tunability. Herein, the techniques and development of applications of tunable metasurfaces are presented through the incorporation of active materials and controllable external stimuli, and the uncovered tunable characteristics are critically analyzed. The review rounds up by proposing the future directions and prospects for actively tunable metasurfaces and their potential practical applications.

show abstract

Durability-enhanced vanadium dioxide thermochromic film for smart windows

Cited by 49 publications

References 34 publications

Solar-assisted fabrication of large-scale, patternable transparent wood

Solar-assisted fabrication of large-scale, patternable transparent wood

Optically Modulated Passive Broadband Daytime Radiative Cooling Materials Can Cool Cities in Summer and Heat Cities in Winter

Tunable Metasurfaces: The Path to Fully Active Nanophotonics

Contact Info

Product

Resources

About