Hyperbranched Fractal Nanocarbons for Bright Photoluminescence in Solid State

Nanocarbons with diverse structures have great potential applications in biomedicine, energy conversion, and catalysis owing to their unique photoelectric properties. This work describes bottom-up synthesis of hyperbranched fractal nanocarbons (HFNs), using trimethylolpropane tri(cyclic carbonate) ether and ethylenediamine as the precursors. HFNs are formed by self-assembly of in situ generated carbonized polymer dots (CPDs), driven by their low surface zeta-potentials. Of significance, both CPDs and HFNs possess graphitized carbon core and functionalized shell with core edge layer, thus emit bright solid-state luminescence with an absolute quantum yield of 11.7% at room temperature and strong phosphorescence at 77 K. The carbonyl cluster of these nanocarbons is mainly responsible for the strong photoluminescence emission. The application of HFNs is demonstrated for energy conversion, using them as single phosphor for fabricating multicolor light-emitting diodes. This work outlines a fundamental principle to prepare HFNs with bright photoluminescence in solid state.