Electrically‐Triggered Oblique Helicoidal Cholesterics with a Single‐Layer Architecture for Next‐Generation Full‐Color Reflective Displays

Abstract Electrically‐induced oblique helicoidal cholesterics (Ch_OH) are attractive for use in reflective displays due to tunable photonic band gap (PBG) in a broad spectral range and natural eye‐friendly feature. However, the lack of a stable liquid crystal (LC) material system with a wide temperature range and unknown driver architecture hinder the implementation of the Ch_OH‐based reflective displays. Here, a prototype for a full‐color reflective display device based on electrically‐tunable Ch_OH‐LC is demonstrated. In the comparison of Ch_OH‐S1, S2 and S3 samples, the electric‐field‐induced Ch_OH in the Ch_OH‐S3 exhibits intense Bragg reflection and a tunable PBG in the extended temperature range from 19.5 °C to 30 °C. Particularly, the resulting device exhibits a lower driving voltage and a relatively larger color gamut for the full‐color reflective displays. On this basis, the display patterns with variable colors are demonstrated via the direct addressing mode. Furthermore, a proof‐of‐concept of the full‐color reflective display is demonstrated with red‐green‐blue pixeled images serving as the active panels. Ultimately, by regulating the electric field strength dependent on the ambient temperature, a stable and vivid effect of the Ch_OH device on the actual environment is shown. This work provides valuable insight for the development of Ch_OH‐based reflective displays.