Shengliang Hu

Bio: Shengliang Hu is an academic researcher from North University of China. The author has contributed to research in topics: Visible spectrum & Carbon. The author has an hindex of 1, co-authored 1 publications receiving 443 citations.

Tunable Photoluminescence Across the Entire Visible Spectrum from Carbon Dots Excited by White Light

Abstract: Although reports have shown shifts in carbon dot emission wavelengths resulting from varying the excitation wavelength, this excitation-dependent emission does not constitute true tuning, as the shifted peaks have much weaker intensity than their dominant emission, and this is often undesired in real world applications. We report for the first time the synthesis and photoluminescence properties of carbon dots whose peak fluorescence emission wavelengths are tunable across the entire visible spectrum by simple adjustment of the reagents and synthesis conditions, and these carbon dots are excited by white light. Detailed material characterization has revealed that this tunable emission results from changes in the carbon dots' chemical composition, dictated by dehydrogenation reactions occurring during carbonization. These significantly alter the nucleation and growth process, resulting in dots with either more oxygen-containing or nitrogen-containing groups that ultimately determine their photoluminescence properties, which is in stark contrast to previous observations of carbon dot excitation-dependent fluorescence. This new ability to synthesize broadband excitable carbon dots with tunable peak emissions opens up many new possibilities, particularly in multimodal sensing, in which multiple analytes and processes could be monitored simultaneously by associating a particular carbon dot emission wavelength to a specific chemical process without the need for tuning the excitation source.

Full-Color Light-Emitting Carbon Dots with a Surface-State-Controlled Luminescence Mechanism.

Abstract: Carbon dots (CDs) with tunable photoluminescence (PL) and a quantum yield of up to 35% in water were hydrothermally synthesized in one pot and separated via silica column chromatography. These separated CDs emitted bright and stable luminescence in gradient colors from blue to red under a single-wavelength UV light. They exhibited high optical uniformity; that is, every sample showed only one peak in the PL excitation spectrum, only one peak in the excitation-independent PL emission spectrum, and similar monoexponential fluorescence lifetimes. Although these samples had similar distributions of particle size and graphite structure in their carbon cores, the surface state gradually varied among the samples, especially the degree of oxidation. Therefore, the observed red shift in their emission peaks from 440 to 625 nm was ascribed to a gradual reduction in their band gaps with the increasing incorporation of oxygen species into their surface structures. These energy bands were found to depend on the surfac...

Carbon and Graphene Quantum Dots for Optoelectronic and Energy Devices: A Review

Abstract: As new members of carbon material family, carbon and graphene quantum dots (CDs, GQDs) have attracted tremendous attentions for their potentials for biological, optoelectronic, and energy related applications. Among these applications, bio-imaging has been intensively studied, but optoelectronic and energy devices are rapidly rising. In this Feature Article, recent exciting progresses on CD- and GQD-based optoelectronic and energy devices, such as light emitting diodes (LEDs), solar cells (SCs), photodetctors (PDs), photocatalysis, batteries, and supercapacitors are highlighted. The recent understanding on their microstructure and optical properties are briefly introduced in the first part. Some important progresses on optoelectronic and energy devices are then addressed as the main part of this Feature Article. Finally, a brief outlook is given, pointing out that CDs and GQDs could play more important roles in communication- and energy-functional devices in the near future.

Engineering triangular carbon quantum dots with unprecedented narrow bandwidth emission for multicolored LEDs

Abstract: Carbon quantum dots (CQDs) have emerged as promising materials for optoelectronic applications on account of carbon’s intrinsic merits of high stability, low cost, and environment-friendliness. However, the CQDs usually give broad emission with full width at half maximum exceeding 80 nm, which fundamentally limit their display applications. Here we demonstrate multicolored narrow bandwidth emission (full width at half maximum of 30 nm) from triangular CQDs with a quantum yield up to 54–72%. Detailed structural and optical characterizations together with theoretical calculations reveal that the molecular purity and crystalline perfection of the triangular CQDs are key to the high color-purity. Moreover, multicolored light-emitting diodes based on these CQDs display good stability, high color-purity, and high-performance with maximum luminance of 1882–4762 cd m−2 and current efficiency of 1.22–5.11 cd A−1. This work will set the stage for developing next-generation high-performance CQDs-based light-emitting diodes.