Metal-insulator transition tuned by valence variation of Nb dopants in Nb-doped VO2 films

Optimizing Phase Transition and Thermochromic Performance of Vanadium Dioxide Thin Films via Erbium Doping

“…Solar modulation ability (Δ Tr sol , 280–3000 nm) and luminance transmittance ( Tr lum , 380–780 nm) are the essential parts of optical properties to evaluate the thermochromic performance of energy-saving smart windows. These two parameters are measured from temperature-dependent UV–vis–IR spectra by following equations , T r normall normalu normalm / normals normalo normall = ∫ ϕ normall normalu normalm / normals normalo normall false( λ false) · T % false( λ false) d λ / ∫ ϕ normall normalu normalm / normals normalo normall false( λ false) d λ normalΔ normalT r normals normalo normall = normalT r normals normalo normall ( 20 .25em ° C ) − normalT r normals normalo normall ( 90 .25em ° C ) where T %(λ), ϕ sol (λ), and ϕ lum (λ) are the spectral transmittance at wavelength λ, the standard spectral irradiance for an air mass of 1.5 corresponding to the sun standing 37° above the horizon, and the standard efficiency function for photopic vision, respectively. UV–vis–NIR transmittance spectra of all samples at 20 and 90 °C in the wavelength range of 200–3000 nm are given in Figure a.…”

“…This result is in agreement with the literature that the hydrothermal growth of VO 2 films on c-cut sapphire substrates is preferably oriented at the (020) plane. 4,6,41 A zoomed view of the (020) peak in the range of 39−42°is given in Figure 1b, which shows the shift of the (020) peak to higher angle with increasing Er doping level, indicating a decrease in (020) interplanar spacing as a result of compressive strain along the out-of-plane direction.…”

“…Solar modulation ability (Δ Tr sol , 280–3000 nm) and luminance transmittance ( Tr lum , 380–780 nm) are the essential parts of optical properties to evaluate the thermochromic performance of energy-saving smart windows. These two parameters are measured from temperature-dependent UV–vis–IR spectra by following equations , where T %(λ), ϕ sol (λ), and ϕ lum (λ) are the spectral transmittance at wavelength λ, the standard spectral irradiance for an air mass of 1.5 corresponding to the sun standing 37° above the horizon, and the standard efficiency function for photopic vision, respectively. UV–vis–NIR transmittance spectra of all samples at 20 and 90 °C in the wavelength range of 200–3000 nm are given in Figure a.…”

Samarium-Doped Vanadium Dioxide Thin Films to Modulate the Thermochromic Properties for Energy-Saving Smart Windows

“…The IR transmission through VO 2 thin films at 20 °C is continuously depressed with Sm doping concentration, and S4 exhibits the lowest IR transmittance. To evaluate the thermochromic properties of Sm-doped VO 2 thin films quantitatively, the integral solar modulation ability (Δ Tr sol , 280–3000 nm) and luminance transmittance ( Tr lum , 380–780 nm) are determined from , Tr lum / sol = prefix∫ Ø lum / sol false( λ false) · T % false( λ false) normald λ / prefix∫ Ø lum / sol false( λ false) normald λ normalΔ Tr sol = Tr sol false( 20 .25em normalC ° false) − Tr sol false( 90 .25em normalC ° false) where T % (λ), Ø lum/sol (λ), and Ø sol (λ) are the spectral transmittance at wavelength λ, the standard spectral irradiance for an air mass of 1.5 corresponding to the sun standing 37° above the horizon, and the standard efficiency function for photopic vision, respectively. The Sm dopant enhances the luminance transmittance and reduces solar modulation, and the Tr lum and Δ Tr sol values of S0–S4 samples are presented in Figure b.…”

Enhancing Thermochromic Properties for Thermal Regulation: A Synergistic Study of Er–W-Codoped Vanadium Dioxide (VO2)

“…% W, while the IR transmittance of S2–S4 is almost the same at 90 °C but lower than that of S1. The Tr lum (280–3000 nm) and Δ Tr sol (280–3000 nm) were evaluated using the following equations , italic italicT italicr normall normalu normalm / normals normalo normall = ∫ Ø normall normalu normalm / normals normalo normall false( λ false) · italicT italicr ⁢ % false( λ false) d λ / ∫ Ø normall normalu normalm / normals normalo normall false( λ false) d λ Δ italicT italicr s o l = T r s o l false( 20 ° normalC false) − T r s o l false( 90 ° normalC false) where Tr % (λ), Ø lum/sol (λ), and Ø sol (λ) are the spectral transmittance at wavelength λ, the standard spectral irradiance for an air mass of 1.5 corresponding to the sun standing 37° above the horizon, and the spectral sensitivity of the light-adapted eye, respectively. The obtained Tr lum and Δ Tr sol values of the S0–S4 thin films are presented in Figure b.…”