Polychromatic display of thermochromic liquid crystals enabled by near-infrared laser scanning

This paper presents a polychromatic display (PD) utilizing thermochromic liquid crystals (TLCs) that exhibit temperature-dependent color changes operated via near-infrared (NIR) laser scanning. TLCs in the cholesteric phase can produce red, green, and blue colors by adjusting their layer spacing and pitch in response to the thermal expansion induced by temperature changes. A simplified TLC-based PD (TLC-PD) panel was constructed by combining a TLC thin film with an NIR absorption and heat-generating functional film, eliminating the need for complex electronic circuits. By inducing a photothermal reaction through NIR laser irradiation, this configuration allows straightforward and precise color image formation without conventional display mechanisms. In addition, the precise control of the red, green, and blue color intensities was achieved by adjusting the NIR laser power, with the display exhibiting response and decay times of ∼4.7 and 5.3 s, respectively. The developed low-power TLC-PD can present full-color text and images in real time through laser scanning, making it applicable in various energy-efficient display technologies.