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

Electrically-induced oblique helicoidal cholesterics (ChOH) 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 ChOH-based reflective displays. Here, a prototype for a full-color reflective display device based on electrically-tunable ChOH-LC is demonstrated. In the comparison of ChOH-S1, S2 and S3 samples, the electric-field-induced ChOH in the ChOH-S3 exhibits intense Bragg reflection and a tunable PBG in the extended temperature range from 19.5 degrees C to 30 degrees 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 ChOH device on the actual environment is shown. This work provides valuable insight for the development of ChOH-based reflective displays. Benefiting from the obtained oblique helicoidal cholesteric (ChOH) with wide temperature range and robust electric-optical performances, here a prototype for full-color reflective display is demonstrated using four-pixels images serving as active display panels under a driving circuit. image