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Angle-independent VO₂ Thin Film on Glass Fiber Cloth as a Soft-Smart-Mirror (SSM).

ABSTRACT: Designing materials with a negative feedback function is beneficial for achieving temperature regulation inside a greenhouse. VO₂ has been studied extensively because of its low insulator-to-metal transition temperature (IMT). In this study, reflection changes during a VO₂ phase transition were investigated. Glass fiber cloth was used as a substrate, as it is stable and soft. A VO₂ thin film on a glass fiber cloth whose surface contained 96% V⁴⁺ and 4% V⁵⁺ was prepared using an inorganic sol-gels method. The insulator-to-metal transition temperature was decreased by 38 °C, which was observed from the reflection curve detected using an angle-resolved spectrometer. This decrease in IMT occurred mainly because of the presence of V⁵⁺, which causes destabilization of the monoclinic phase of VO₂. When the greenhouse temperature was increased from 30 °C to 40 °C, the reflected intensity of VO₂ on glass fiber cloth decreased by 22% for the wavelength range of 400 nm to 800 nm. In addition, the angle-independent property of the VO₂ thin film was observed using an angle-resolved spectrometer. Owing to its thermo-reflective properties, the thin film can serve as a soft-smart-mirror (SSM) inside a greenhouse to stabilize the temperature, playing a negative feedback role.

SUBMITTER: Cai N

PROVIDER: S-EPMC5110969 | biostudies-literature |

REPOSITORIES: biostudies-literature

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Project description:Over the years, vanadium dioxide, (VO2(M1)), has been extensively utilised to fabricate thermochromic thin films with the focus on using external stimuli, such as heat, to modulate the visible through near-infrared transmittance for energy efficiency of buildings and indoor comfort. It is thus valuable to extend the study of thermochromic materials into the mid-infrared (MIR) wavelengths for applications such as smart radiative devices. On top of this, there are numerous challenges with synthesising pure VO2 (M1) thin films, as most fabrication techniques require the post-annealing of a deposited thin film to convert amorphous VO2 into a crystalline phase. Here, we present a direct method to fabricate thicker VO2(M1) thin films onto hot silica substrates (at substrate temperatures of 400 °C and 700 °C) from vanadium pentoxide (V2O5) precursor material. A high repetition rate (10 kHz) femtosecond laser is used to deposit the V2O5 leading to the formation of VO2 (M1) without any post-annealing steps. Surface morphology, structural properties, and UV-visible optical properties, including optical band gap and complex refractive index, as a function of the substrate temperature, were studied and reported below. The transmission electron microscopic (TEM) and X-ray diffraction studies confirm that VO2 (M1) thin films deposited at 700 °C are dominated by a highly texturized polycrystalline monoclinic crystalline structure. The thermochromic characteristics in the mid-infrared (MIR) at a wavelength range of 2.5-5.0 μm are presented using temperature-dependent transmittance measurements. The first-order phase transition from metal-to-semiconductor and the hysteresis bandwidth of the transition were confirmed to be 64.4 °C and 12.6 °C respectively, for a sample fabricated at 700 °C. Thermo-optical emissivity properties indicate that these VO2 (M1) thin films fabricated with femtosecond laser deposition have strong potential for both radiative thermal management or control via active energy-saving windows for buildings, and satellites and spacecraft.

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Angle-independent VO₂ Thin Film on Glass Fiber Cloth as a Soft-Smart-Mirror (SSM).

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OmicsDI is part of the ELIXIR infrastructure

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Dataset Information

Angle-independent VO2 Thin Film on Glass Fiber Cloth as a Soft-Smart-Mirror (SSM).

Similar Datasets

OmicsDI is part of the ELIXIR infrastructure

Tweets

Angle-independent VO₂ Thin Film on Glass Fiber Cloth as a Soft-Smart-Mirror (SSM).