Electrochromic smart materials

“Smart Windows”

What are Smart Windows?

Smart Windows are windows which use a glazing material to

control the amount of light that is allowed to pass through the

glass panes.

The glazing material is often called “switchable glazing”.

These materials change their optical behaviour with

application of electrical voltage.

Various Terms for Smart Glass

Types of Smart Glasses

Active Smart Glass

Electrochromic

Suspended particle device (SPD)

Polymer dispersed liquid crystal (PDLC)

Glass-ITO/LixWO3/PEO-LiN(SO2CF3)2/Liy(TiO2 – CeO2)/ITO/glassGlass/ITO/polytoluidine/cellulose – polyacetate polymer/ Hy(TiO2 –CeO2/ITO/glass

Ability to tune optical transmission from

clear to dark.

Low switching speed.

Lack complete opacity.

Requires electricity only to change

opacity, not to maintain

SPD – Suspended Particle Devices

Microscopic light-absorbing particles are dispersed in droplets within a film.

In the "off" state the particles are suspended randomly, making the window dark.

At moderate voltage is applied the particles align and permit light to pass through.

SPD Transmittance

Angle prespective Voltage perspective

PDLC – Polymer dispersed Liquid crystal

Beats:1. Switching speed.

Opacity of dark state.

Most expensive option.

Switches to milky white in

less then a secund

Material When is

transparen

t

Continuous states

between opaque

and transparent

Requires power to

maintain the state

Pros Cons

Electrochromic Switched

OFF

YES NO Widely used

(cheap), no „E”

for maintainig the

translucent state

Long transition

time,

new glass must

be installed

SPD ON YES YES Fast, Clear to

tinted

Bad at blocking

IR (poor

performance)

PDLC ON NO YES External, Internal

use, good

efficiency entire

spectrum

expensive

Conclusion

References:

1. C.G. Granqvis, Journal of the European Ceramic Society 25 (2005) 2907–2912

2. David Barrios, Ricardo Vergaz, Jose M. Sanchez-Pena, Claes G. Granqvist, Gunnar A. Niklasson

Solar Energy Materials & Solar Cells 111 (2013) 115-122

3. Anna Llorde ´s1, Guillermo Garcia1, Jaume Gazquez2 & Delia J. Milliron Nature vol. 500 (2013)

323-327

4. Baetens, R.; Jelle, B.P.; Gustavsen, A. Solar Energy Materials and Solar Cells 94 (2) (2010): 87–105.

5. Lee, E.S.; Tavil, A. Building and Environment 42 (6) (2007). : 2439–2449

6. Wiki…. Google…

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