Graphene QDs yield bright blue AC-electroluminescence eeNews Europe

Researchers from the Korea Advanced Institute of Science and Technology (KAIST) have been able to unlock the electroluminescence of Graphene Quantum Dots (GQDs) through their dispersion into a boron oxynitride powder.As a research project of Global Frontier Program – KAIST Advanced Battery Center, Professor Seokwoo Jeon’s research team sought to improve the photoluminescence of GQDs for their use as an active electroluminescent (EL) material in light-emitting devices. Emerging GQDs have attracted significant attention for use as a next-generation EL material due to their biocompatibility, low-cost fabrication, and excellent optical properties. However, in the solid-state, they show complete loss of photoluminescence (PL) due to the π-interaction induced aggregation-caused PL quenching. Demonstrating a novel, simple approach, the research team were able to build efficient solid-state photoluminescent GQD embedded in boron oxynitride powder (GQD@BNO) for a highly bright alternating-current powder electroluminescent (ACPEL) device. The effective dispersal of GQDs in the BNO matrix significantly suppressed the aggregation effects, resulting in a high photoluminescence quantum yield (PL-QY) of up to 36.4 %, eight-fold higher than that of pristine GQDs in water, the researchers reported. According to their analysis, the PL-QY enhancement results from an increase in the spontaneous emission rate of GQDs due to the surrounding BNO matrix, which provides a high refractive index material and fluorescence energy transfer from the larger gap BNO donor to the smaller gap GQD acceptor. The efficient dielectric environment of the BNO matrix makes GQD@BNO a suitable active material for use in ACPEL devices, with the luminance of the first working GQDs-based ACPEL device exceeding 283 cd m-2. Korea Advanced Institute of Science and Technology (KAIST) - www.kaist.ac.kr