Intelligent Window Coatings:  Atmospheric Pressure Chemical Vapor Deposition of Tungsten-Doped Vanadium Dioxide

Abstract

Thin films of tungsten-doped vanadium(IV) oxide were prepared on glass substrates from the atmospheric pressure chemical vapor deposition of vanadium(IV) chloride, tungsten-(VI) ethoxide, and water at 500-600 °C. The films were characterized by Raman microscopy, glancing angle X-ray diffraction (GAXRD), X-ray photoelectron spectroscopy (XPS), Rutherford backscattering (RBS), scanning electron microscopy (SEM), and vis/IR reflectancetransmittance. The films showed a reduction in thermochromic transition temperatures from 68 °C in VO 2 to 42 °C in V 0.99 W 0.01 O 2 sapproaching that required for commercial use as an intelligent window coating.

Structural and Morphological Characterization of Magnetron Sputtered Nanocrystalline Vanadium Oxide Films for Thermochromic Smart Surfaces

“…This first-order transition is accompanied by a large change of electrical resistivity and reflectance in the infrared region [1] which makes these materials attractive for applications such as optical/electrical switching devices [2][3][4], electrochromic systems [5], data storage devices [6,7], etc. Among them, VO 2 is the most interesting because its transition temperature is close to room temperature, ~68ºC [1], and therefore is being under many studies in an effort to apply it in smart energy efficient windows with active solar control [8][9][10][11][12]. The stoichiometry of VO 2 has been reported as a determinant factor for an improved thermochromic performance [13][14][15].…”

Electric Fields and Chemical Vapor Deposition

“…Previous work has reported the presence of fully oxidized vanadium at the surface (29), as such the multiple environments are not surprising. However, a V 3+ environment at the surface is unusual and normally found in the bulk of the material and associated with doping by W 6+ (9).…”

“…It was found the most effective metal ion dopant was tungsten (9). Tungsten doped VO 2 films have been prepared by a variety of methods including sol-gel (10), sputtering (11), and CVD methodologies (6,(12)(13)(14)(15)(16)(17)(18)(19)(20)(21)(22)(23)(24).…”

A Synthesis of Pure Monolayer VO2 Films with High Visible Transmittance

“…9 If VO 2 is used in applications like smart windows, the visible transmittance should exceed 60%. [10][11] However, the visible transmittance values reported for VO 2 thin films are quite low, and the transmittance maximum in the visible region (380-780 nm) has been reported to be ≈ 50%, [12][13] 42%, 14 45%, 15 or less than 40%. [16][17][18][19][20] Many methods have been investigated in an effort to improve the visible transmittance for VO 2 thin films.…”