Multicolour nitrogen-doped carbon dots: tunable photoluminescence and sandwich fluorescent glass-based light-emitting diodes

The first use of the combination of ammonium citrate (AC) and ethylenediamine tetraacetic acid (EDTA) as coordinating precursors for the synthesis of highly fluorescent (quantum yield = 67%) multicolour nitrogen-doped carbon dots (CDs) is reported. Under UV light, these CDs emitted outstanding luminescence in colours from dark blue to red. Interestingly, a single component white-light CD point with high fluorescence efficiency was obtained by surface control. Alterations of the photoluminescence (PL) emission of these full-colour CDs were tentatively proposed to benefit from surface functional groups, such as CO and CN. An energy-level model was proposed to explain the continuously adjustable full-colour emission. The white light may be attributed to the overlap of diverse light emission induced by electron transitions between the energy levels. Subsequently, to avoid aggregation-induced solid-state fluorescence quenching, multicolour CD-based sandwich glasses with various colour emission was fabricated, which is anticipated to be compatible with the all-optical light-emitting diodes (LEDs). The facile preparation and outstanding optical features are believed to provide an alternative synthesis route and inspire more research into applications and CD-based materials of multicolour CDs.