Integrated experimental and simulation study on chiral–MgO nanoparticle synergistic tuning of PDCLC devices

Abstract

Polymer-dispersed cholesteric liquid crystal (PDCLC) films doped with magnesium oxide nanoparticles (MgO NPs) were successfully fabricated via polymerization-induced phase separation (PIPS). The synergistic effect of chiral dopant (R1011) and MgO NPs on the electro-optical properties of PDCLC was systematically investigated. It was found that the droplet size, threshold voltage (Vth), saturation voltage (Vsat), and contrast ratio (CR) exhibited a non-monotonic dependence on the concentration of R1011, achieving an optimal CR of 24.5 at a relatively high Vsat (>70 V) when doped with 1.38 wt% R1011. The subsequent incorporation of 0.6 wt% MgO NPs notably reduced the Vsat to 45 V while maintaining an acceptable CR of 16.4, significantly enhancing device performance. Finite-difference time-domain (FDTD) simulations revealed that the optical transmittance of the PDCLC device strongly correlates with the molecular deflection angle, surpassing 90% when the deflection angle reaches 90°. Moreover, the presence of MgO NPs substantially improved the initial transmittance by modulating liquid crystal-polymer interfacial interactions at the molecular scale. This study provides quantitative insights into the relationship between the liquid crystal director distribution and optical performance, highlighting the promising potential of MgO NP-doped PDCLC films for applications in smart windows and energy-efficient display technologies.