Oxygen-less Carbon Nanodots with an Absolute Quantum Yield of 80% for Display Applications

Carbon nanodots (CNDs) are organic-based particulate fluorophores prepared using various carbon-containing sources such as bulk carbon materials (e.g., graphite and coal) and organic molecules (e.g., carbohydrates, organic acids, and amino acids). Despite the wide variety of sources, the formation of CNDs almost always requires a specific type of oxidation reaction, and CNDs are generally regarded as highly oxidized carbon materials, similar to graphitic oxide. The oxide structures of CNDs are known to not only play a crucial role in the realization of photoluminescence but also induce oxygen-related defects that may degrade the optoelectronic properties. Therefore, we report an oxygen-free synthesis of CNDs with extremely low oxygen contents based on the pyrolysis-induced decarboxylation of aromatic carboxylic acids. The CNDs exhibit very strong excitation-independent photoluminescence in the yellow to orange range of the visible spectrum, with an absolute quantum yield that ranges up to 80%. Finally, we successfully fabricated freestanding color filters using these CNDs to demonstrate their potential in future display applications.