Friday, 20 July 2012

Thermochromic glass (II)

As we have seen, thermochromic coatings have two problems:
-) High critical temperature,
-) Limited visible transmittance. Today we write about this.
Through experimental observations, Babulanam and Granqvist noted as an anti-reflection coating of SiO2 contribute to increase the light transmittance of the glass.
In details, it is compared: the luminous transmittance between a device with only a glassy layer of 200 nm of VO2 and one with VO2 in turn covered with a film of SiO2, having various thicknesses.
The results show that, with a thickness of 100 nm of SiO2, the luminous transmittance at a wavelength of 650 nm increases from 42% to about 55% at 20 °C, justifying what has been said.
Many compositions have been analyzed to create such a protective film, including those based on SnO2, In2O3 or CeO2. I want to cite the use of  TiO2 as important because of its possible applications in DSSC (dye-sensitized solar cells) called Gr├Ątzel cells (photoelectrochemical cells) which will be discussed shortly.

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