A sunlight-driven smart window using guest-host liquid crystals based on opto-thermal conversion of near-infrared dye

Abstract

We demonstrate controllable transmittance in an NIR-GH-LC device mediated by irradiation with pseudo-sunlight. Optical phase transition is induced in the proposed NIR-GH-LC device by the opto-thermal conversion of near-infrared dye, and the transparent and colored states are controlled with dichroic dye. Our results indicate that the optical phase transition can be observed upon irradiation with pseudo-sunlight when the concentration of near-infrared dye is 5 wt%, with the dichroic black dye also contributing to the optical phase transition via opto-thermal conversion. We find that the proposed NIR-GH-LC device can be switched between the transparent and colored states by irradiation with pseudo-sunlight. The NIR-GH-LC device is attractive for applications in self-shading smart windows that can be driven by sunlight.

Keywords:

• Guest-host
• liquid crystals
• near-infrared dye
• opto-thermal conversion
• smart window

Acknowledgments

The authors thank Nissan Chemical Industries, Ltd. and Hayashibara Co. Ltd. for providing the alignment films and the functional dyes.