Aqueous/Alcohol-Soluble Carbon Dot Light-Emitting Diodes.

Fluorescent carbon dots (CDs), benefiting from their environmental friendliness, solution processability, tunable emission spectra, and high photoluminescence efficiency, have shown great promise for next-generation solid-state lighting and flat panel displays. CDs are typically synthesized via hydrothermal methods, exhibiting excellent solubility in water and alcohols. However, due to the absence of suitable alcohol-soluble host materials, aqueous/alcohol-soluble CDs have so far failed to achieve electroluminescence. Herein, a bipolar host material named 2PCT is specifically designed for aqueous/alcohol-soluble CD-based electroluminescent light-emitting diodes (LEDs). Specifically, the introduction of donor-acceptor units and diethyl phosphite groups enables 2PCT to have excellent bipolar transport properties and film-forming capability. Moreover, the high solubility of 2PCT in ethanol and low production cost position it as a promising candidate for large-scale green manufacturing of CD-based LEDs. Using 2PCT as the host material, we have successfully fabricated multicolor (green, yellow, and red) CD-LEDs with record-breaking performance benchmarks among ethanol-processed CD-based optoelectronic devices. Benefiting from the alcohol-compatible processing, we have further achieved air-stable fabrication of CD-LEDs with an extended emission area of 16 cm2, which holds significant potential for large-area optoelectronic applications.