Emmanouil Gagaoudakis; Giannis Michail; Elias Aperathitis; Ioannis Kortidis; Vassilios Binas; Marianthi Panagopoulou; Yannis S. Raptis; Dimitris Tsoukalas; George Kiriakidis
Abstract
The high deposition temperature of the order of 400 o C and more is requirement for the growth of the thermochromic phase of vanadium dioxide (VO2), limits the type of substrates that one may grow them on only to rigid ones. In this work, thermochromic VO2 films were successfully deposited on flexible ...
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The high deposition temperature of the order of 400 o C and more is requirement for the growth of the thermochromic phase of vanadium dioxide (VO2), limits the type of substrates that one may grow them on only to rigid ones. In this work, thermochromic VO2 films were successfully deposited on flexible Corning® Willow® glass substrates, without the use of a buffer layer, by rf sputtering at a substrate temperature of 300 o C, one of the lowest for this technique ever reported. The critical transition temperature of 80 nm thin films was Tc = 50.7 o C, transmittance hysteresis width was ΔT = 12.1 o C, while the modulation of the transmittance at λ = 2000 nm measured at 25 o C and 90 o C was around 36%, leading to a solar modulation of ΔTrsol = 5%. In addition, an increase in transmittance at λ = 600nm (visible region) of 4% was observed before and after heating, while integrated luminous transmittance remained almost constant at Trlum = 34%. The thermochromic and luminous characteristics of the VO2 films deposited on flexible glass are comparable to those deposited on rigid glass substrates. The deposition of thermochromic VO2 film on flexible glass substrates by sputtering technique opens up a new window for thermochromic applications on flexible substrates.
Dimitrios Louloudakis; Dimitra Vernardou; Emmanuel Spanakis; Mirela Suchea; George Kenanakis; Martyn Pemble; Konstantinos Savvakis; Nikolaos Katsarakis; Emmanuel Koudoumas; George Kiriakidis
Abstract
Amorphous tungsten doped vanadium dioxide coatings were grown on SnO2-precoated glass substrates using the atmospheric pressure chemical vapor deposition of vanadium (V) triisopropoxide and tungsten (VI) isopropoxide at 450 o C without an oxygen source. The effect of N2 flow rate through the tungsten’s ...
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Amorphous tungsten doped vanadium dioxide coatings were grown on SnO2-precoated glass substrates using the atmospheric pressure chemical vapor deposition of vanadium (V) triisopropoxide and tungsten (VI) isopropoxide at 450 o C without an oxygen source. The effect of N2 flow rate through the tungsten’s precursor bubbler was examined keeping the respective flow rate through the vanadium’s precursor bubbler at 4 L min -1 for a growth period of 30 min. They were characterized by x-ray diffraction, Raman and x-ray photoelectron spectroscopy, field-emission scanning electron microscopy and UV-vis/IR transmittance. The samples grown using 0.4 L min -1 N2 flow rate through the tungsten precursor’s bubbler, showed the greatest reduction in transition temperature from 65.5 in granular VO2 to 44 o C in worm-like V0.985W0.015O2 structures approaching that required for commercial use as a smart window coating.
