Electrically tunable UV–visible modulation and voltage-controlled quantum dot emission via polymer network liquid crystals

Abstract

Dynamic modulation of ultraviolet (UV) and visible light is important for smart windows, adaptive photonics, and emerging display technologies. Here we report a vertically aligned polymer network liquid crystal (PNLC) platform that enables electrically tunable UV–visible light control with high optical clarity and low operating voltage. Using a negative dielectric anisotropy liquid crystal and optimized UV polymerization, the PNLC device exhibits high transparency in the field-off state (~83% transmittance with ~1.5% haze) and switches to a strongly scattering state (~90% haze) under applied electric fields. Electro-optical switching begins at ~1.5 V μm-1 and saturates near ~3.4 V μm-1, with attenuation governed by field-induced refractive-index mismatch rather than intrinsic absorption. By integrating the PNLC shutter with InP/ZnSe/ZnS QD/NOA composite layers, we demonstrate electrical modulation of quantum dot (QD) photoluminescence (PL) through excitation gating. Green and red QDs emit at ~530 and ~630 nm and show reversible intensity modulation with high modulation depth (~92–97%). The device also exhibits millisecond-scale switching and stable operation over repeated cycles. This architecture establishes a quantum dot liquid crystal display (QD-LCD) concept, offering a pathway toward high-brightness, long-lifetime, and low-voltage photonic and display systems.