N-Doped Carbon Dots Embedded in Silica Nanoparticles with Multicolor Luminescence for Light-Emitting Devices

To overcome the aggregation-caused quenching of carbon dots (CDs) in the solid state, this work presented a facile approach for in situ synthesis of N-doped CDs (N-CDs) in silica particles with the assistance of a bifunctional organic base, tetramethylammonium hydroxide (TMAOH). In this approach, TMAOH first acted as a basic catalyst, which can dissociate into TMA+ and OH–, to direct the growth of TMA+-embedded SiO2 particles. The TMA+ in silica particles was then used as the precursor for in situ synthesis of N-CDs via pyrolysis, resulting in the formation of N-CD-embedded SiO2 (N-CDs/SiO2) particles. The N-CDs/SiO2 particles presented tunable emission color from blue to green and yellow, depending on the amounts of TMAOH used in the reactions. More importantly, the resulting N-CDs/SiO2 particles exhibited bright and stable emission in both solution and solid states, making them potentially useful in the fabrication of anti-counterfeiting labels and light-emitting devices.