S,N-Codoped oil-soluble fluorescent carbon dots for a high color-rendering WLED†
Carbon dots (CDs) have attracted widespread attention in light-emitting-diode (LED) applications owing to their environmental friendliness, easy processing and unique optical properties. For the practical use of CDs in LEDs, the controllable synthesis of high performance oil-soluble carbon dots is still in urgent demand. In this study, S,N-codoped oil-soluble carbon dots (S,N-OCDs) with an average size of 3.38 nm were prepared by solvothermal reaction of acetone, dimethyl trithiocarbonate (DMTTC) and nitric acid. Characterization results reveal that both the conjugated aromatic π systems from the aldol condensation and highly active free radicals from DMTTC essentially dominate the development of these yellow-green emitting S,N-OCDs, which possess high carbonization, quantum yield (21.08%) and oil-solubility. Furthermore, a white light-emitting-diode (WLED) was fabricated through mixing the obtained S,N-OCDs and epoxy and drop-casting the mixture on the surface of gallium nitride (GaN)-based blue chips. The as-prepared WLED showed excellent color rendering properties (CCT of 5389 K, CIE coordinates of (0.33, 0.30), and CRI of 88.38).