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Electrically switchable polymer stabilised broadband infrared reflectors and their potential as smart windows for energy saving in buildings.

Khandelwal H, Loonen RC, Hensen JL, Debije MG, Schenning AP - Sci Rep (2015)

Bottom Line: Simulations predict that a significant amount of energy can be saved on heating, cooling and lighting of buildings in places such as Madrid by using this switchable IR reflector.We have also fabricated a switchable IR reflector which can also generate electricity.These polymer based switchable IR reflectors are of high potential as windows of automobiles and buildings to control interior temperatures and save energy.

View Article: PubMed Central - PubMed

Affiliation: 1] Functional Organic Materials and Devices, Department of Chemical Engineering and Chemistry, Eindhoven, University of Technology, Den Dolech 2, 5600 MB Eindhoven, the Netherlands [2] Dutch Polymer Institute (DPI), P.O. Box 902, 5600 AX Eindhoven, The Netherlands.

ABSTRACT
Electrically switchable broadband infrared reflectors that are relatively transparent in the visible region have been fabricated using polymer stabilised cholesteric liquid crystals. The IR reflectors can change their reflection/transmission properties by applying a voltage in response to changes in environmental conditions. Simulations predict that a significant amount of energy can be saved on heating, cooling and lighting of buildings in places such as Madrid by using this switchable IR reflector. We have also fabricated a switchable IR reflector which can also generate electricity. These polymer based switchable IR reflectors are of high potential as windows of automobiles and buildings to control interior temperatures and save energy.

No MeSH data available.


Related in: MedlinePlus

a) Transmission spectrum of IR reflector on varying the applied voltage from 0 V/μm to 8.6 V/μm b) Transmission spectrum of cholesteric gel in reflective and transmissive states at 0 V/μm and 8.6 V/μm, respectively c) Switching measurements shows stable bandwidth after 600 cycles between 0 V/μm and 8.6 V/μm.
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f4: a) Transmission spectrum of IR reflector on varying the applied voltage from 0 V/μm to 8.6 V/μm b) Transmission spectrum of cholesteric gel in reflective and transmissive states at 0 V/μm and 8.6 V/μm, respectively c) Switching measurements shows stable bandwidth after 600 cycles between 0 V/μm and 8.6 V/μm.

Mentions: After successfully fabricating the infrared reflecting gel, we have studied the switching behaviour by applying an electric voltage. At zero to approximately 2.1 V/μm, the gel exhibits a broad infrared reflection band with high transparency in the visible region. On further increasing the voltage (e.g. 5.4 V/μm), scattering in the visible region increases while reflection in the infrared remains approximately the same (Fig. 4a). This could be attributed to tilting of the cholesteric liquid crystal yielding most likely a focal conic state along with some unwinding of the helix, resulting in more scattering4950. Such a situation (at 5.4 V/μm) could be useful as a ‘privacy’ state of a window device, effectively controlling IR transmission while simultaneously causing a scattering state which is translucent but not transparent. On further increasing the voltage to 8.6 V/μm, the liquid crystal gel becomes transparent to infrared as well as visible light (Fig. 4b). This effect is attributed to homeotropic orientation of the E7 molecules505152.


Electrically switchable polymer stabilised broadband infrared reflectors and their potential as smart windows for energy saving in buildings.

Khandelwal H, Loonen RC, Hensen JL, Debije MG, Schenning AP - Sci Rep (2015)

a) Transmission spectrum of IR reflector on varying the applied voltage from 0 V/μm to 8.6 V/μm b) Transmission spectrum of cholesteric gel in reflective and transmissive states at 0 V/μm and 8.6 V/μm, respectively c) Switching measurements shows stable bandwidth after 600 cycles between 0 V/μm and 8.6 V/μm.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4487232&req=5

f4: a) Transmission spectrum of IR reflector on varying the applied voltage from 0 V/μm to 8.6 V/μm b) Transmission spectrum of cholesteric gel in reflective and transmissive states at 0 V/μm and 8.6 V/μm, respectively c) Switching measurements shows stable bandwidth after 600 cycles between 0 V/μm and 8.6 V/μm.
Mentions: After successfully fabricating the infrared reflecting gel, we have studied the switching behaviour by applying an electric voltage. At zero to approximately 2.1 V/μm, the gel exhibits a broad infrared reflection band with high transparency in the visible region. On further increasing the voltage (e.g. 5.4 V/μm), scattering in the visible region increases while reflection in the infrared remains approximately the same (Fig. 4a). This could be attributed to tilting of the cholesteric liquid crystal yielding most likely a focal conic state along with some unwinding of the helix, resulting in more scattering4950. Such a situation (at 5.4 V/μm) could be useful as a ‘privacy’ state of a window device, effectively controlling IR transmission while simultaneously causing a scattering state which is translucent but not transparent. On further increasing the voltage to 8.6 V/μm, the liquid crystal gel becomes transparent to infrared as well as visible light (Fig. 4b). This effect is attributed to homeotropic orientation of the E7 molecules505152.

Bottom Line: Simulations predict that a significant amount of energy can be saved on heating, cooling and lighting of buildings in places such as Madrid by using this switchable IR reflector.We have also fabricated a switchable IR reflector which can also generate electricity.These polymer based switchable IR reflectors are of high potential as windows of automobiles and buildings to control interior temperatures and save energy.

View Article: PubMed Central - PubMed

Affiliation: 1] Functional Organic Materials and Devices, Department of Chemical Engineering and Chemistry, Eindhoven, University of Technology, Den Dolech 2, 5600 MB Eindhoven, the Netherlands [2] Dutch Polymer Institute (DPI), P.O. Box 902, 5600 AX Eindhoven, The Netherlands.

ABSTRACT
Electrically switchable broadband infrared reflectors that are relatively transparent in the visible region have been fabricated using polymer stabilised cholesteric liquid crystals. The IR reflectors can change their reflection/transmission properties by applying a voltage in response to changes in environmental conditions. Simulations predict that a significant amount of energy can be saved on heating, cooling and lighting of buildings in places such as Madrid by using this switchable IR reflector. We have also fabricated a switchable IR reflector which can also generate electricity. These polymer based switchable IR reflectors are of high potential as windows of automobiles and buildings to control interior temperatures and save energy.

No MeSH data available.


Related in: MedlinePlus