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Novel Reversible Humidity‐Responsive Light Transmission Hybrid Thin‐Film Material Based on a Dispersive Porous Structure with Embedded Hygroscopic and Deliquescent Substances
Author(s) -
Castellón Erick,
Zayat Marcos,
Levy David
Publication year - 2018
Publication title -
advanced functional materials
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 6.069
H-Index - 322
eISSN - 1616-3028
pISSN - 1616-301X
DOI - 10.1002/adfm.201704717
Subject(s) - materials science , transmittance , thin film , porosity , layer (electronics) , light scattering , relative humidity , optoelectronics , composite material , chemical engineering , scattering , optics , nanotechnology , physics , engineering , thermodynamics
The article describes a new concept of an optical hybrid thin‐film material that exhibits reversible humidity‐driven light transmittance (scattering) properties. The film consists of a dispersive porous structure, with embedded hygroscopic and deliquescent compounds, that is able to scavenge water molecules from humid air to fill up the pores and become transparent to the incident light. Upon exposure to dry air, water is released from the structure and the material recovers its original light scattering properties. The developed thin films can change their transparency when exposed to air with different relative humidity (RH), adjusting the light throughput. This material can, therefore, be used to design new optical switching systems, having the advantage that they do not require liquid crystal, transparent conductive glass substrates, or complex layer‐by‐layer architectures for operation. In this work, a thin film was prepared by the sol–gel technique using calcium chloride as deliquescent substance embedded in a hybrid silica–titania matrix. At dry air, the thin films show a highly dispersive state, with a light transmittance T = 0.06, while at 51% RH the film exhibits a transparent state with a transmittance T =0.67 (measured at 633 nm).