Recent Progress in Liquid Crystal-Based Smart Windows: Materials, Structures, and Design

Abstract

As the vital elements for building environments, windows are utilized to bring light as well as thermal irradiation into the interior places and afford the medium for the communication between the interior and exterior of buildings. Liquid crystal (LC)-based smart windows, which are mainly made of LC materials or polymer/LC composites, can dynamically modulate light transmittance and regulate the heat radiation entering buildings from the sun via the orientation variation of the LC molecules. Such smart windows play an important role in intelligent buildings and building energy conservation, which contributes to providing a more comfortable and low-energy-consumption living environment for mankind. In this review, recent progress in LC-based smart windows of each category is overviewed. New materials, new ideas, and new methods to improve the performance of conventional LC-based smart windows and create novel smart window technologies are outlined. Different advanced LC-based smart window technologies, including electrochromism, thermochromism, photochromism, humidity-triggered chromism, mechanical self-powered technique, and dynamic infrared regulating mechanisms, are discussed systematically. The applications of LC-based smart windows in indoor illumination/privacy protection switching, human-machine interaction, and thermal regulation for intelligent buildings are highlighted. Last, the challenges and perspectives of LC-based smart windows are also provided.