Color–Tunable Triple–State “Smart” Window

Abstract

Materials that rapidly change their optical properties in response to external stimuli are crucial for displays and “smart” window applications. Herein, a fluorescent red dye modified with liquid crystal (LC) side chains is described to be interactive with a LC host, resulting in a color‐tunable triple‐state smart window. The dye solubilizes in the LC matrix with increasing temperature, resulting in a red‐colored, absorbing state, recovering transparency again by reaggregation of the dye within minutes upon cooling. This dye is used to fabricate a device that can be electrically switched from a red‐colored, absorbing state to an intermediate scattering state and at greater electrical fields, a transparent state. Using a second dichroic fluorescent dye, heating the device transitions the window's color from yellow/green to red. The multiresponsive optical changes could find applications in many fields, including displays, smart windows, electricity generation, and signage.

Keywords

• dye aggregation
• liquid crystals
• perylene bisimide
• responsive
• “smart” windows