Transmission variation using scattering/transparent switching layers

Helen Rose Wilson; Wolfgang Eck

doi:10.1117/12.130542

25 November 1992 Transmission variation using scattering/transparent switching layers

Helen Rose Wilson, Wolfgang Eck

Proceedings Volume 1728, Optical Materials Technology for Energy Efficiency and Solar Energy Conversion XI: Chromogenics for Smart Windows; (1992) https://doi.org/10.1117/12.130542
Event: Optical Materials Technology for Energy Efficiency and Solar Energy, 1992, Toulouse-Labege, France

Abstract

Due to the fallibility of mechanical shading devices such as shutters or blinds, thin films with variable transmittance, which can be applied directly to a glazing surface, are being investigated for so-called `smart windows' or for applications together with transparent insulating materials. In the films discussed here, the transmittance is changed by varying the scattering properties, which depend on changes in the effective refractive index and/or size of microstructures. This may be achieved by orientation and relaxation of birefringent liquid crystal molecules within polymer-encapsulated droplets by applying an electric field, by reversible separation and mixing of two polymers with temperature variation, or by exploiting the Christiansen effect. In this paper, the effect of varying experimentally accessible parameters on the transmittance change is first explored theoretically by applying Mie and multiple scattering theories. These results are complemented by measurements of the spectral dependence of the transmittance and reflectance of the first two types of switching samples, i.e., polymer-dispersed liquid crystal (PDLC) films and thermotropic layers of polymer blends. Changes of almost 40% in the visual and solar direct-hemispherical transmittance were measured for the range of sample thicknesses investigated here.

Citation Download Citation

Helen Rose Wilson and Wolfgang Eck "Transmission variation using scattering/transparent switching layers", Proc. SPIE 1728, Optical Materials Technology for Energy Efficiency and Solar Energy Conversion XI: Chromogenics for Smart Windows, (25 November 1992); https://doi.org/10.1117/12.130542

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