Jianle Zhuang

A Self-Quenching-Resistant Carbon-Dot Powder with Tunable Solid-State Fluorescence and Construction of Dual-Fluorescence Morphologies for White Light-Emission

Self-quenching in the aggregation state is overcome, and tunable solid-state photoluminescence of carbon-dot powder is achieved. Furthermore, based on the controllable optical property in organic solvents, a novel concept, i.e., constructing dual-fluorescence morphologies from single luminescent species, is presented to realize white-light emission.

Solid‐State Carbon Dots with Red Fluorescence and Efficient Construction of Dual‐Fluorescence Morphologies

Stable solid-state red fluorescence from organosilane-functionalized carbon dots (CDs) with sizes around 3 nm is reported for the first time. Meanwhile, a novel method is also first reported for the efficient construction of dual-fluorescence morphologies. The quantum yield of these solid-state CDs and their aqueous solution is 9.60 and 50.7%, respectively. The fluorescence lifetime is 4.82 ns for solid-state CDs, and 15.57 ns for their aqueous solution. These CDs are detailedly studied how they can exhibit obvious photoluminescence overcoming the self-quenching in solid state. Luminescent materials are constructed with dual fluorescence based on as-prepared single emissive CDs (red emission) and nonfluorescence media (starch, Al2 O3 , and RnOCH3 COONa), with the characteristic peaks located at nearly 440 and 600 nm. Tunable photoluminescence can be successfully achieved by tuning the mass ratio of CDs to solid matrix (such as starch). These constructed dual-fluorescence CDs/starch composites can also be applied in white light-emitting diodes with UV chips (395 nm), and oxygen sensing.

Phytotoxicity, Uptake, and Translocation of Fluorescent Carbon Dots in Mung Bean Plants

Fluorescent carbon dots (CDs) have been widely studied in bioscience and bioimaging, but the effect of CDs on plants has been rarely studied. Herein, mung bean was adopted as a model plant to study the phytotoxicity, uptake, and translocation of red emissive CDs in plants. The incubation with CDs at a concentration range from 0.1 to 1.0 mg/mL induced physiological response of mung bean plant and imposed no phytotoxicity on mung bean growth. The lengths of the root and stem presented an increasing trend up to the treatment of 0.4 mg/mL. Confocal imaging showed that CDs were transferred from the roots to the stems and leaves by the vascular system through the apoplastic pathway. The uptake kinetics study was performed and demonstrated that the CDs were abundantly incubated by mung beans during both germination and growth periods. Furthermore, in vivo visualization of CDs provides potential for their successful application as delivery vehicles in plants based on the unique optical properties.

Towards efficient dual-emissive carbon dots through sulfur and nitrogen co-doped

Herein, unique S and N co-doped carbon dots (S,N-C-dots) were synthesized via a one-pot hydrothermal method. The S,N-C-dots not only possess a relatively high photoluminescence (PL) quantum yield (QY) (43%), but also present unique optical properties with dual-emission (blue and yellow) and excitation-independent characteristics. It is extremely rare for bare carbon dots (C-dots) to have dual-emission under single excitation wavelength. Herein, we achieved a series of solid-state lighting materials, such as silica-encapsulated C-dots (silica/C-dots), light conversion films (LCFs), and white-light-emitting diodes (WLEDs), using S,N-C-dots as a doping fluorophore. Moreover, we conducted some comparative experiments to prove that the unique properties of the S,N-C-dots were ascribed to the co-doping effects of S and N atoms. The yellow emission originates from the intrinsic state emission and the blue emission originates from the surface energy trap emission. This study presents a facile preparation of highly efficient dual-emissive S,N-C-dots and provides a new strategy to develop various solid-state lighting materials.

Double carbon dot assembled mesoporous aluminas: solid-state dual-emission photoluminescence and multifunctional applications

Carbon dot (CD)-based solid-state fluorescent materials have attracted a lot of attention in recent years owing to their superior optical and environmentally friendly properties, demonstrating a potential use in many applications. However, previously reported CD-based solid-state fluorescent materials mostly assemble a type of CD in the matrix which has only a single characteristic peak, and those of assembled double CDs with two characteristic peaks are very rare. Such a drawback restricts their further application, particularly in the field of white light emitting diodes (WLEDs). Herein, a rare type of double CD-based fluorescent material has been synthesized with dual characteristic peaks at 420 nm and 635 nm via the one-step assembly of blue- and red-emissive carbon dots (bCDs, rCDs) into mesoporous aluminas (MAs). The MA non-fluorescent matrix neither competes for absorbing excitation light nor absorbs the emission from the CDs, leading to excellent PL emitting properties and color and thermal stabilities. The emissive colors are tunable in the white-light region simply through adjusting excitation wavelengths, showing their great potential for phosphor-based WLEDs. In the field of agricultural planting, transparent sunlight conversion films based on co-assembled phosphors have been obtained, revealing inherent optical properties and an efficient process for converting sunlight into blue and red lights, which are essential for plant photosynthesis.

Preparation and properties of dual-mode luminescent NaYF4:Yb,Tm@SiO2/carbon dot nanocomposites

Herein, NaYF4:Yb,Tm@SiO2/carbon dot nanocomposites have been successfully fabricated by a facile route. The structure and morphology of the nanocomposites were characterized by SEM, TEM, XRD, FT-IR and XPS measurements. It was demonstrated that carbon dots were embedded well in the silica layer coating on the surface of NaYF4:Yb,Tm nanoparticles, leading to a relatively stable structure of the nanocomposites. The nanocomposites showed interesting dual-mode luminescence properties, i.e. blue green light under a 365 nm UV lamp and blue purple light under a 980 nm laser. They were utilized to achieve light conversion films, ion detection probes and cell imaging, suggesting their great potential in the fields of anti-counterfeiting and bioapplications.

Correction: Towards efficient dual-emissive carbon dots through sulfur and nitrogen co-doped

Correction for ‘Towards efficient dual-emissive carbon dots through sulfur and nitrogen co-doped’ by Wan Zhou et al., J. Mater. Chem. C, 2017, 5, 8014–8021.

Near-Ultraviolet to Near-Infrared Fluorescent Nitrogen-Doped Carbon Dots with Two-Photon and Piezochromic Luminescence

Carbon dots (CDs) have gained intensive interests owing to their unique structure and excellent optoelectronic performances. However, to acquire CDs with a broadband emission spectrum still remains an issue. In this work, nitrogen-doped CDs (N-CDs) with near-ultraviolet (NUV), visible, and near-infrared (NIR) emission were synthesized via one-pot solvothermal strategy, and the excitation-independent NUV and NIR emission and excitation-dependent visible emission were observed in the photoluminescence (PL) spectra of N-CDs. Moreover, the as-synthesized N-CDs displayed two-photon fluorescence emission. It is important to note that N-CDs also exhibited piezochromic luminescence with reversibility, in which the red- and blue-shifted PL with increasing applied pressure (0.07-5.18 GPa) and the red- and blue-shifted PL with releasing applied pressure (5.18 GPa to 1 atm) were developed for the first time. Combined with good hydrophilicity, high photobleaching resistance, and low toxicity, the piezochromic luminescence would greatly boost the valuable applications of N-CDs.

Controlled Synthesis of BaYF 5 :Er 3+ , Yb 3+ with Different Morphology for the Enhancement of Upconversion Luminescence

In this work, Er3+/Yb3+-codoped BaYF5 with different sizes and shapes have been synthesized by a simple solvothermal method. By changing the fluoride source, pH value, solvent, surfactants, Yb3+ concentration, temperature, and reaction time, the optimum synthetic conditions of BaYF5:Er3+, Yb3+ were found to improve the upconversion luminescent properties. It is found that the emission intensity of green and red light is enhanced for several times by the way of using NaBF4 as a fluoride source with the comparison of NH4F and NaF. Moreover, the effects of different surfactants are not the same. Adding 5% polyetherimide (PEI) as surfactant can also improve the upconversion emission. On the contrary, when sodium citrate (CIT) as another surfactant was used to add, the sizes of the nanocrystals were gradually increased and the luminous properties also declined.