Facile synthesis of high-brightness green-emitting carbon dots with narrow bandwidth towards backlight display

High-performance carbon dots(CDs)allowing the application in high-end display devices are highly desirable and usually limited by the absence of simple and easy synthesis methods.In this work,we exploited an easy-to-implement strategy for the one-step synthesis of green-emitting CDs(G-CDs)with superb optical properties.The G-CDs were synthesized using m-phenylenediamine(m-PD)as a single precursor,and the reaction reacted at 180℃for 12 h The resultant G-CDs exhibit high-purity and excitationindependent green fluorescence with the photoluminescence(PL)peak located at 516 nm,full width at half maximum(FWHM)of 46 nm,and PL quantum yield(QY)of∼80%under the 470nm excitation light.The G-CDs and corresponding composite film prepared with polyvinyl butyral(G-CDs@PVB)exhibit good PL stability after undergoing long-time storage for one year and 360 h exposure under 460nm blue light.The G-CDs@PVB film was used as color-conversion materials in green-emitting light-emitting diode(LED)application,exhibiting a Commission internationale de l’Eclairage(CIE)chromaticity coordinate of(0.21,0.44).The film was also used in CD-based liquid crystal display(CD-LCD)application,achieving a color gamut value of 85%.This work will offer a working basis for the synthesis of high-performance CDs as well as their application in displays.

Ultrastable and ultrasensitive pH-switchable carbon dots with high quantum yield for water quality identification,glucose detection,and two starch-based solid-state fluorescence materials

It is attractive and encouraging to develop new fluorescent carbon dots(CDs)with excellent optical properties and promising applications prospects.Herein,highly-efficient green emissive CDs(m-CDs)with a high quantum yield(QY)of 71.7%in water are prepared through a facile solvothermal method.Interestingly,the m-CDs exhibit excellent fluorescence stability in the pH range of 1–9.However,the fluorescence intensity of the m-CDs is almost completely quenched as the pH is increased from 9 to 10.The mechanism of the unique pH-responsive behavior is discussed in detail and a plausible mechanism is proposed.Owing to the unique pH-responsive behavior,the m-CDs are used as a on-off fluorescent probe for water quality identification.By combining the reversible pH-ultrasensitive optical properties of the m-CDs in the pH range of 9–10 with the glucose oxidase-mimicking(GOx-mimicking)ability of Au nanoparticles(AuNPs),glucose can be quantitatively detected.Finally,two environment-friendly starch-based solid-state fluorescence materials(powder and film)are developed through green preparation routes.

Red-emitting,self-oxidizing carbon dots for the preparation of white LEDs with super-high color rendering index

Carbon dots(CDs),as a kind of carbon nanomaterials,have attracted widespread attention due to their unique structure and excellent optical properties,and they are low-cost,environmentally friendly and biocompatible.However,the development of near-infrared(NIR)emission CDs remains a challenge.In this study,we successfully prepared CDs with a maximum emission of714 nm using citric acid as the carbon source,thiourea and ammonium fluoride as the dopant source,and N,N-dimethylformamide as the solvent.The quantum yield(QY)is as high as 22.64%.Interestingly,the prepared CDs self-oxidize in the presence of oxygen,resulting in a blue shift of their emission.Therefore,they can be used to prepare white light-emitting diodes(WLEDs)without adding other fluorescent substances.Notably,the work presented herein constitutes the first report of WLEDs preparation from single CDs.

Photo-induced Ag modulating carbon dots:Greatly improved fluorescent properties and derived sensing application

Carbon dots(CDs)have been attracted much attention and widely studied due to their excellent fluorescence(FL)properties,better biocompatibility and outstanding photo/chemical stability.However,the disadvantage of lower quantum yield(QY)still limits its wide application.Herein,we reported a novel and convenient strategy to prepare photo-induced Ag/CDs(p-Ag/CDs)by irradiating the mixed Ag+and hydrophobic CDs(h-CDs)acetone solution with ultraviolet(UV)light.The obtained p-Ag/CDs exhibit a greatly enhanced FL emission together with a blue shift(460 nm)than h-CDs(520 nm).The QY of p-Ag/CDs is measured to be 51.1%,which is 10.4 times higher than that of h-CDs(4.9%),indicating that photo-induced Ag modulation can effectively improve the optical properties of CDs.The mechanisms for the FL enhancement and blue shift of h-CDs are studied in detail.The results prove that the greatly enhanced FL emission is from the generated Ag nanoparticles(AgNPs)by UV light irradiation based on metal-enhanced fluorescence(MEF),and the increased oxygen-contained groups in this process lead to the blue shift in CDs fluorescence.Interestingly,the p-Ag/CDs exhibit higher sensitivity and selectivity for sulfide ions(S2-)detection than that of h-CDs,which have a lower response to S2-.This work not only offers a novel strategy to improve the FL properties of materials but also endows them with new functions and broadens their application fields.

Controllable emission bands and morphologies of high-quality CsPbX3 perovskite nanocrystals prepared in octane

Halide perovskite （CsPbX3, X = C1, Br, or I） quantum dots have received increasing attention as novel colloidal nanocrystals （NCs）. Accurate control of emission bands and NC morphologies are vital prerequisites for most CsPbX3 NC practical applications. Therefore, a facile method of synthesizing CsPbX3 （X = C1, Br, or I） NCs in the nonpolar solvent octane was developed. The process was conducted in air at - 90℃ to synthesize high-quality CsPbX3 NCs showing 12-44 nm wide emission and high photoluminescence quantum yield, exceeding 90%. An in situ anion-exchange method was developed to tune CsPbX3 NC photoluminescence emission, using PbX2 dissolved in octane as the halide source. NC morphology was controlled by dissolving specific metal-organic salts in the precursor solution prior to nucleation, and nanocubes, nanodots, nanosheets, nanoplatelets, nanorods, and nanowires were obtained following the same general method providing a facile, versatile route to controlling CsPbX3 NC emission bands and morphologies, which will broaden the range of CsPbX3 NC practical applications.

Lead-Free Hybrid Indium Perovskites with Highly Efficient and Stable Green Light Emissions

Lead halide perovskite nanocrystals(PNCs)have emerged as new-generation light-emitting materials with important potentials in optoelectronic applications.However,the toxicity of lead metal and the instabilities of PNCs overwhelmingly hinder their device engineering;thus,it is still urgent to construct new single crystalline lead-free perovskites with high-performance luminescent properties.

Novel seven-membered ring-fused naphthalimide derivatives with potentials for cancer theranostics

Naphthalimide derivatives have good planarity and large conjugated structure and therefore possess photophysical properties and biological activities. Previously, our group discovered seven-membered heterocyclic derivatives via modifying 4-and 5-positions of naphthalimide skeleton and found the derivatives had good water solubility and showed large stokes shift and strong fluorescence in water. In this article, we designed and synthesized more seven-membered ring-fused naphthalimide derivatives(Y1-Y16)by introducing different substitutions on the imide group. Among them, Y1, Y5, Y9 were found to show similar cytotoxic activities with Amonafide against A549 and HL60 cells, with IC50values at 10^(-6)mol/L.What is more, the asymmetry derivatives(Y1 and Y5) showed high fluorescent quantum yields in the aqueous phase(Ф = 0.47). Considering the great fluorescence quantum yields in water and the potent anti-tumor activities of the representative seven-membered ring-fused naphthalimides, they have potentials to be used as agents for cancer theranostics.