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

Khandelwal, Hitesh; Loonen, Rcgm Roel; Hensen, Jlm Jan; Debije, Michael G.; Schenning, Albertus P. H. J.

doi:10.1038/srep11773

Cited by 104 publications

(50 citation statements)

References 59 publications

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“…7 that the de ector acts as a retrore ector when the de ection angle is equal to the angle of incidence (θ d = θ i ). In the sample studied, this occurs at θ i = 22.1°; this optical e ect should be useful, for example, when applying these lms on windows to re ect thermal radiation from the sun back to its original direction [18].…”

Section: Evaluation Of the Deflection Anglementioning

confidence: 99%

Circularly-polarized, large-angle reflective deflectors based on periodically patterned cholesteric liquid crystals

Kobashi¹,

Mohri²,

Yoshida³

et al. 2017

Optical Data Processing and Storage

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Patterned cholesteric liquid crystals enable the fabrication of circular-polarization sensitive, re ective di ractive optical elements based on Bragg re ection. Here we report the fabrication of large-angle re ective deector, which show de ection angles as large as 48.9°. The devices are fabricated by polarization holography, whereby two orthogonal circular polarized beams are superimposed on a photoalignment layer to create a linear modulation of the orientational easy axis. The devices show high circular-polarization extinction ratios, making them potentially useful as functional re ectors and polarization splitters.

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Section: Evaluation Of the Deflection Anglementioning

confidence: 99%

Circularly-polarized, large-angle reflective deflectors based on periodically patterned cholesteric liquid crystals

Kobashi¹,

Mohri²,

Yoshida³

et al. 2017

Optical Data Processing and Storage

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“…However, these reflectors reflect only a limited fraction of incident solar light, and some of them interfere with visible light. In contrast, electrically tunable IR reflectors, which based on the so-called polymer stabilized cholesteric liquid crystal (PSCLC) can selectively reflect different fractions of infrared radiation on demand without affecting the transmittance in the visible region [26][27][28][29].…”

Section: Introductionmentioning

confidence: 99%

Cell thickness dependence of electrically tunable infrared reflectors based on polymer stabilized cholesteric liquid crystals

Haan

Khandelwal

et al. 2017

Sci. China Mater.

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We reported here the fabrication of the electrically tunable infrared (IR) reflectors based on the polymer stabilized cholesteric liquid crystal (PSCLC) with negative dielectric anisotropy. A systematic study of the influence of cell gap on the electrically tunable reflection bandwidth was performed. When a direct current (DC) electric field was applied, the reflection bandwidth red shifted in the cells with small cell gap, whereas the bandwidth broadening was observed in the cells with large cell gap. It is therefore reasonable to deduct that the reflection is dictated by the pitch gradient steepness which strongly relies on the cell thickness. The results reveal that for making PSCLC based IR reflector windows with electrically induced bandwidth broadening, a minimal cell gap thickness is required. The resulted IR reflectors possess a short native switching time and long-term operation stability, and are potentially applicable as smart energy saving windows in buildings and automobiles.

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“…They obtained a lower operating voltage and a higher cutoff rate of infrared light, compared to ITO or ZITO-based smart windows. Khandelwal et al [10] fabricated electrically switchable broadband infrared reflectors using polymer stabilized cholesteric liquid crystals. They predicted that their reflector can save more than 12% of energy compared to double glazing window and 9.3% compared to static infrared reflector.…”

Section: Introductionmentioning

confidence: 99%

A Spectrally Selective Window for Hot Climates

Sid-Ahmed¹,

Bilal²,

Babiker³

2017

JECTC

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Rigorous coupled-wave analysis has been used to design a glazing for hot climates. The designed glazing is relatively simple and it transmits most of the visible light and reflects most of the infrared radiation. It does not need any external source of energy to control its optical properties. It consists of ITO and four periodic pairs of Si/SiO 2 , deposited on a glass sheet. The optimum thicknesses of ITO, Si and SiO 2 are 0.1 μm, 0.15 and 0.4 μm, respectively. The glazing acts as an optically selective filter. It transmits about 80% of the visible light and reflects almost all the infrared radiation. The performance of the glazing is almost independent of the angle of incidence of solar radiation. This makes it suitable for all hours of the day. The fabrication of the glazing and the testing have been performed at the laboratories of the Faculty of Science, University of Witwatersrand, South Africa. Magnetron sputtering technique has been used for the fabrication. ITO, Si and SiO 2 have been used as sputtering targets. The experimental results are almost identical to the simulation results.

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

Cited by 104 publications

References 59 publications

Circularly-polarized, large-angle reflective deflectors based on periodically patterned cholesteric liquid crystals

Circularly-polarized, large-angle reflective deflectors based on periodically patterned cholesteric liquid crystals

Cell thickness dependence of electrically tunable infrared reflectors based on polymer stabilized cholesteric liquid crystals

A Spectrally Selective Window for Hot Climates

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