Reflective Narrow-band-infrared Polymer-dispersed Cholesteric Liquid Crystals for Electronic Writing Displays

초록

A polymer-dispersed cholesteric liquid crystal (PDCLC) is a composite material formed by blending cholesteric liquid crystals with polymer, and is renowned for exceptional optical-modulation capabilities. This study focuses on the development of a narrowband infrared reflective film with high transmittance in the visible-light spectrum and enhanced reflectivity at near-infrared wavelengths, specifically at 850 nm. By adjusting the number of cholesteric layers, the birefringence of the liquid-crystal materials, and the concentration of dopants, we control the film's reflectivity, saturation, and chromaticity. Bragg reflection theory is employed to predict material parameters and reflectance behavior, ensuring precise optical design. The film is fabricated using HSG44700-200 and R811 liquid-crystal materials, mixed in a mass ratio of 83:17, combined with the polymer NOA65 in a ratio of 30:70. The resulting film achieves a visible-light transmittance of 80% and an infrared reflectivity of 45% at 850 nm. Leveraging these properties, the film is successfully integrated into an electronic dot-matrix-pen display system, significantly enhancing infrared-recognition performance, especially improving optical-code-recognition rates at tilted angles. This study provides a novel approach and technical foundation for the development of high-performance optical films for electronic writing displays.

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