Tunable light emission using crystalline carbon dots

Carbon quantum dots (CQDs) with an approximate size of 8 nm were prepared by a simple and cost-effective green technique—pyrolysis of cotton. Synthesized CQDs exhibit broad fluorescence covering almost blue and green light wavelengths. They show low cytotoxicity and good photostability. A simple mixing of rhodamine 6G chloride with highly fluorescent carbon dots in water led to aggregation of dye molecules on carbon dot surface. Controlling the emission of free rhodamine 6G dye with that of the resultant carbon dot-aggregated rhodamine 6G composite resulted in efficient white light emission with the CIE coordinate (0.305, 0.313). Suitable mixture of blue-light-emitting CQD in aqueous solution and rhodamine 6G dye can potentially be applied for tunable white light emission.