Carbon Quantum Dots doped Cholesteric Liquid Crystal Films and Microdroplets for Anti-Counterfeiting

Developing superior and adaptable structural colors for anticounterfeiting technologies remains a challenge, despite the widespread usage of structurally colored materials in anticounterfeiting applications. We present a anticounterfeiting material, structural colored cholesteric liquid crystals (CLCs), in conjunction with synthesized fluorescent carbon quantum dots (CQDs). CQDs doped with a CLC mixture display a green reflection in daylight owing to the structural chiral arrangement of CLCs and a cyan color when exposed to UV light (365 nm) due to the fluorescence emission of CQDs. A glass capillary microfluidic approach was also used to create CLC microdroplets doped with fluorescent CQDs. In daylight, the fluorescent CLC microdroplets showed center spot reflection with a green hue and photonic cross communication and fluorescent cyan emission color when exposed to UV light. CLC microdroplets with fluorescent CQDs have potential applications in smart dual-mode displays, anticounterfeit labeling, and smart decoratives.