Recently, the team of Zhang Yang and Fan Louzhen from the School of Chemistry published a paper titled "Pure-violet oxygen-doped carbon quantum rings with near-unity quantum yield and a full-width at half-maximum of 18 nm" in Nature Synthesis.

This paper introduces pure-violet CQRs with a wide optical bandgap (3.3 eV), an ultranarrow-bandwidth emission of 18 nm and a near-unity PLQY of up to 95%, synthesized through a facile one-pot solid-state reaction. This work provides a strategy for the design and synthesis of emitters with ultranarrow bandwidth and near-unity PLQY, paving the way for the realization of high-colour-purity violet LEDs for use in wide-colour-gamut displays.

Abstract:

High-colour-purity violet light-emitting diodes (LEDs) with colour coordinates close to the human visual threshold are essential for achieving wide-colour-gamut displays. However, it remains challenging for visible-light emitters to achieve both luminescence peaks shorter than 400 nm and a full-width at half-maximum (FWHM) below 20 nm due to irreducible π-conjugation length and strong vibrational relaxation in the excited state. Here this study introduces planar oxygen-doped carbon quantum rings (OD-CQRs) composed of twelve benzene rings and six embedded five-membered oxygen heterocycles. These OD-CQRs exhibit a fluorescence peak centre at 393 nm, a FWHM of 18 nm and a photoluminescence quantum yield of 95%. Detailed structural characterizations coupled with theoretical calculations reveal that the ring profile and alternatively embedded oxygen heterocycles in OD-CQRs effectively suppress π-electron delocalization and excited-state vibrational relaxation, due to non-bonding electron characteristics. The electroluminescent LEDs based on OD-CQRs demonstrate high-colour-purity violet emission with chromaticity coordinates of (0.161, 0.017), approaching the edge of the visible colour space.

Reference: https://doi.org/10.1038/s44160-025-00922-4