Thermochromic VO2 Coating Modulates Solar Radiation
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
There is a need for thermochromic materials that can be used as window coatings to provide energy savings for buildings by effectively modulating solar radiation while maintaining high visible light transmission, as existing materials do not adequately balance solar modulation and visible light transmission.
Innovation Solution
A thermochromic material comprising vanadium (IV) oxide with a specific preparation method involving a two-step thermal treatment process using different oxygen concentrations, which results in a coating with a high SunSmart Factor (SSF) of Tvis*ΔTsol > 600, achieving high visible light transmission and solar modulation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If VO2 is used in window coatings to block solar infrared light, then energy consumption for cooling decreases, but visible light transmission is reduced
Solution Approach 1:
The patent modifies the switching temperature parameter of VO2 from 68°C to 25-30°C through doping with metal ions, allowing the thermochromic effect to occur at ambient temperatures relevant to building cooling, thereby achieving energy savings without sacrificing visible light transmission
Solution Approach 2:
The patent utilizes the reversible metal-to-semiconductor phase transition of VO2 between monoclinic (low temperature) and rutile (high temperature) phases, which causes selective modulation of infrared radiation while maintaining visible light transmission, resolving the contradiction between energy blocking and light transmission
2Temperature
If VO2 switching temperature is decreased through doping, then thermochromic effect occurs at lower temperatures, but manufacturing complexity increases
Solution Approach 1:
The patent systematically investigates different metal ion dopants (W, Mo, Ta, Nb, Al, F) and their concentrations to achieve the desired switching temperature of 25-30°C, balancing performance optimization with manufacturability by selecting from well-established doping techniques
Solution Approach 2:
The patent employs controlled oxidation during the thermal treatment process to convert vanadium precursors to VO2 while incorporating metal ion dopants, using oxygen concentration control to manage the complexity of the manufacturing process
3Temperature
If thermal treatment is performed at high temperature under nitrogen atmosphere, then VO2 phase transition is achieved, but oxygen concentration control becomes critical
Solution Approach 1:
The patent uses a two-stage thermal treatment process with periodic changes in atmosphere composition: first stage under nitrogen for phase transition, second stage with controlled oxygen introduction to optimize VO2 formation and dopant incorporation, managing oxygen concentration dynamically throughout the process
Solution Approach 2:
The patent monitors and controls oxygen concentration during thermal treatment to achieve optimal VO2 formation, using feedback control to adjust oxygen partial pressure and maintain the balance between complete oxidation and preservation of the thermochromic phase
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The thermochromic material effectively reduces energy consumption in buildings by modulating solar radiation, achieving significant energy and cost savings, as demonstrated by the increased SunSmart Factor and modeled energy savings in residential buildings.
Implementation Method 1
Vanadium (IV) oxide (VO2) is known as being able to undergo a fully reversible metal-to-semiconductor phase transition between a low temperature monoclinic phase VO2 (M) and a high temperature rutile phase VO2 (R)
Implementation Method 2
The rutile phase is a semi-metal, reflecting and/or absorbing a wide range of solar wavelengths in the infrared. The monoclinic phase is a semiconductor and reflects and/or absorbs considerably less solar infrared light
Implementation Method 3
The rutile phase is a semi-metal, reflecting and/or absorbing a wide range of solar wavelengths in the infrared
Implementation Method 4
The monoclinic phase is a semiconductor and reflects and/or absorbs considerably less solar infrared light
Implementation Method 5
the method comprising: providing a liquid formulation comprising an organometallic V(IV) complex in solution and a reactive diluent and/or binder material; drying the liquid formulation at least partly into a solid material; and thermally treating the solid material
Implementation Method 6
the first treatment step is performed at a first oxygen concentration of at least 5 vol % and a temperature below 300° C., and the second treatment step involves further heating to increase the temperature by at least 100° C. under an oxygen concentration that is lower than in the first treatment step
Data Source
AI summary
The disclosure pertains to thermochromic materials, coatings, to coated articles and to preparation methods. In addition, the disclosure relates to thermochromic particulate material comprising vanadium (IV) oxide. A described preparation method involves curing of the coating using two curing stages performed with different oxygen levels.