Photoluminescent UV Light Modulation via Anisometric Carbon Nanodots for UV–Visible Shutter and UV Sensor

Carbon nanodots (CNDs) are promising photoluminescent nanomaterials due to their excellent optical properties, environmental benignity, and cost‐effective synthesis from abundant precursors. However, their practical integration into optoelectronic devices is hindered by low synthetic yield, limited processability, and poor compatibility with host media. In contrast, liquid crystals offer electrical tunability and optical anisotropy, yet their potential in multifunctional platforms enabling simultaneous UV‐ and visible‐light modulation remains underutilized. Here, the synthesis of anisometric CNDs and their incorporation into polymer network liquid crystals (PNLCs) are reported to construct a multifunctional optoelectronic system that exhibits UV–vis photoluminescence, light modulation, and UV sensing. The CNDs are uniformly aligned within nematic hosts, exhibiting broad UV absorption and polarized visible photoluminescence, with an emission dichroic ratio of ≈1.63. The resulting hybrid film functions as UV–vis light shutters and photonic sensors, exhibiting ≈93.1% transmittance and ≈8.4% haziness in the transparent state, and switching to ≈13.3% transmittance and ≈89.9% haziness in the scattering state, with rapid response times (≈7.6 ms turn‐on, ≈5.4 ms turn‐off). Notably, the photoluminescence intensity is electrically and optically tunable, exhibiting a twofold change upon applied voltage and external UV exposure. This dual‐responsive and polarized emission behaviors open new avenues for smart windows and adaptive optical technologies.