Synthesis of trichromatic carbon dots from a single precursor by solvent effect and its versatile applications

Multi-color is the fundamental for display, white LED (WLED), and bioimaging. Three kinds of carbon dots (co-doped of S and N elements) (S,N-CDs) with red (R), green (G) and blue (B) fluorescence were synthesized using 2,5-Diaminobenzenesulfonicacid as the only precursor by a simple, environmentally friendly solvent modulation method, which neither needed complex precursor formulations nor tedious post-processes to obtain multi-color performance. Compared to the previous S,N-CDs, our CDs has a higher fluorescence quantum yield and tunable colors which implies a higher resolution in detection and deeper penetration in tissue observation. We present their outstanding roles in chemical trace detection and light source application to demonstrate their application potential. The three CDs were highly sensitive and could selectively recognize Ag+ and Fe3+ with low limit of detection of up to 35 and 23 nM, respectively. The CDs were mixed to fabricate WLED in solution, solid (with lotus root powder) and xerogel forms, achieved satisfactory white light properties with CIE (1931) coordinates (0.32,0.33), (0.31, 0.32) and (0.33, 0.35), respectively, almost pure white light. This is digestible light source and fluorescent biomarker that open up possibilities for in vivo recycling-free imaging applications.