Resistance to aggregation-caused quenching: chitosan-based solid carbon dots for white light-emitting diode and 3D printing

Solid state emission carbon dots have replaced traditional phosphors and become the most promising new-generation color conversion layer, which are used to produce low-cost, environmentally friendly, and low-energy consumption white light-emitting diode (WLED). Here, chitosan-based solid state carbon dots (C-SS-CDs) with yellow fluorescence and a yield of 90% were successfully obtained from chitosan via a one-step hydrothermal synthesis. The research results confirmed that the C-SS-CDs inherited the basic backbone structure of chitosan moieties and prevented the π-π interaction between carbon cores, thereby inhibiting the occurrence of aggregation caused quenching (ACQ) in the solid state. Meanwhile, the existence of fluorescence resonance energy transfer (FRET) facilitates long wavelength emission of C-SS-CDs in highly concentrated solution and solid state. The photoluminescence quantum yield (PLQY) of C-SS-CDs in dilute acid solution is 40%, which can be used for the detection of Fe 3+ ions in acidic systems. The C-SS-CDs were mixed with epoxy resin and curing agent to obtain C-SS-CDs/epoxy resin composites, which were coated onto the 450 nm chip, thereby successfully obtaining a WLED with the color rendering index of more than 90. In addition, C-SS-CDs/epoxy composites can also obtain 3D anti-counterfeiting and warning signs by 3D printing. Graphical Abstract Chitosan-based solid emission carbon dots were applied to white light-emitting diode with color rendering index over 90 and 3D printing.