智能窗的热致变色VO2薄膜

(≈68℃)
Q2:Low visible transmittance
(<50%)
Q3:Weak optical contrast in the IR region
Q4:Unfavorable color & Immature processing
For us
God is impartial , who endows a kind of material with outstanding properties while in turn hard to prepare.
Thermochromic VO2 thin film for smart window
Y.C.Zhou T.Y.Zhou J.Q.zheng • Y.J.Zhou
Table of contents
1
Introduction Methods of synthesis Problems & Solutions
Without PVP
PVP
Merits of Sol-gel method
Low cost
Ease for doping
Sol-gel
Easy handling
Large scale process
Chemical vapor deposition
Diffusion Vaporization of Precursor and Transport Molecules of to Precursor Surfaceto Molecules Adsorption of Precursor Molecules Surface into Reactor Decomposition of Precursor Molecules on Surface and Incorporation into Phase Solid Film Recombination of Molecular Byproducts and Desorptiowk.baidu.com into Gas
[1] Jinqian Wu,Qian Gu , Nanoletter,2006 Vol.6,No.10,2313-2317. [2] Litao Kang,†,‡ Yanfeng Gao, ACS,Applied material & interfaces, VOL. 1 • NO. 10 • 2211–2218 • 2009
Resistance of a suspended VO2 nanobeam measured in a four-probe geometry as a function of temperature [1]
Optical transmittance spectra of VO2 film [2]
2
3
Winter
To outside
Roof 5%
Ventilation 15%
Summer
From outside
Roof 11%
Ventilation 6%
Wall15%
Wall 7%
Window 58%
Floor 7%
Window 73%
Floor 3%
Working principle
-Y.J.Zhou
VCl 4 2 H 2 O VO2 4 HCl
Uniformity
Repeativity CVD
Large scale
Good substrate adhesion
Film thickness control
Problems
Q1:High MIPT temperature
Applications ???
VO2 undergoes reversible transition at critical temperature Tc (68℃) ; below 68℃ ，VO2 is semiconducting and relatively infrared transparent,and above Tc it is metallic and infrared reflecting.(NIR:0.78-2.5um)
Methods of synthesis
Sol-gel method
★
Chemical vapor deposition ★ DC、RF&magnetron sputtering Pluse laser deposition
Sol-gel method
Mixing solution (HCl,N2H4,V2O5)
Adjust pH
Sol
(Only VOCl2)
Adding PVP
Gel
Spin coating
Final product
Annealing
Second product
Drying
Primary product
[5] Litao Kang,Yanfeng Gao,J.Phys.Chem.C ,2010,114,1901-1911