One-Pot Exfoliation of Graphitic C₃N₄ Quantum Dots for Blue QLEDs by Methylamine Intercalation

Here, a simplified synthesis of graphitic carbon nitride quantum dots (g-C₃N₄-QDs) with improved solution and electroluminescent properties using a one-pot methylamine intercalation–stripping method (OMIM) to hydrothermally exfoliate QDs from bulk graphitic carbon nitride (g-C₃N₄) is presented. The quantum dots synthesized by this method retain the blue photoluminescence with extremely high fluorescent quantum yield (47.0%). As compared to previously reported quantum dots, the g-C₃N₄-QDs synthesized herein have lower polydispersity and improved solution stability due to high absolute zeta-potential (−41.23 mV), which combine to create a much more tractable material for solution processed thin film fabrication. Spin coating of these QDs yields uniform films with full coverage and low surface roughness ideal for quantum dot light-emitting diode (QLED) fabrication. When incorporated into a functional QLED with OMIM g-C₃N₄-QDs as the emitting layer, the LED demonstrates ≈60× higher luminance (605 vs 11 Cd m⁻²) at lower operating voltage (9 vs 21 V), as compared to the previously reported first generation g-C₃N₄ QLEDs, though further work is needed to improve device stability.