Luting Ling

Triphase Microfluidic‐Directed Self‐Assembly: Anisotropic Colloidal Photonic Crystal Supraparticles and Multicolor Patterns Made Easy

However, it is stilla great challenge to mount or shape CPCs into a desiredmorphology (e.g., spheres, Janus, ellipsoids, and dumbbell-like supaparticles); efficient pathways are needed to selec-tively endow CPCs with versatile functions whilst preservingtheir original optical properties.Herein, we developed a triphase microfluidic-directedself-assembly to construct CPC supraparticles with control-lable and predictable shape, and selectively introducedadvanced functions to them. The triphase microfluidictechnique is a co-flowing system that produces continuousmicrodroplets comprising two immiscible phases. By adjust-ing the interfacial tension of each phase in the microfluidicsystem, CPC supraparticles with tunable shape, varying fromcrescent, meniscus, and ellipsoid to spherical were preparedbytheself-assemblyofthemonodispersecolloidalparticlesinthese microdroplet templates. Importantly, studying theinterfacechemistryindicatedthatthestructureofthebiphasicmicrodroplets and the resulting CPCs might be predicted inour strategy. The further introduction of photoinducedconsolidation into the triphase microfluidic system yieldedcore–shell or Janus CPC superstructures. The encapsulationof magnetic nanoparticles created Janus CPC supraparticleswith superparamagnetism and a photonic bandgap in twodistincthemispheres.ThesemultifunctionalJanusCPCsupra-particles exhibit “Dark” and “Light” switchable behaviorsunder an external magnetic field, and thus can be processedinto rewritable and color-tunable photonic patterns. To ourknowledge, this is the first example of the utilization of thetriphase microfluidic technique for the design of anisotropicCPCs. This facile strategy can be extended to build up aseriesofnovelmultidimensionalcolloidalstructures,withtheaimofcollecting colloidal particles and orgnizing them into func-tional materials for pratical application.Figure 1a illustrates the fabrication of shape-controllableCPC supraparticles in a triphase microfluidic flow-focusingdevice composed of a cylindrical polydimethylsiloxane(PDMS) capillary and a pair of inner cylindrical 25G steelneedles. We chose three immiscible fluids, an aqueoussolution of monodisperse polystyrene (PS) microspheres in

Fluorescent nanomaterial-derived white light-emitting diodes: what's going on

White light-emitting diodes (white LEDs) have recently attracted substantial interest owing to their remarkable energy conservation. The evolution of fluorescent nanomaterials with tunable optical properties has provided an opportunity for light source design of white LEDs. However, the stability and performance of fluorescent nanomaterial-derived white LEDs still fail to meet the requirements of practical applications. It is therefore imperative to boost their overall device performance, which depends on not only the exploitation of advanced fluorescent nanomaterials but also the design of a superior light source. In this review, the achievements regarding fluorescent nanomaterials as color converters towards white LEDs are highlighted, including semiconductor nanocrystals or colloidal quantum dots (QDs), carbon-based nanoparticles, silicon QDs, and organic–inorganic fluorescent nanocomposites. The challenges and future perspectives in this research area are also discussed.

Versatile dendrimer-derived nanocrystal microreactors towards fluorescence colloidal photonic crystals

The ability to finely bind colloidal photonic crystals with nanocrystals (NCs) is critical in many applications ranging from light-emitting devices to flexible displays and biological labels. Herein, the use of carbosilane–thioether generation 2 vinyl-terminated (G2-Vi) dendrimers facilitates zero dimensional (0D) and two dimensional (2D) microreactors with high-uptake NCs, allowing them to generate fluorescent colloidal photonic crystals. Dendrimer-functionalized microspheres were prepared by seeded copolymerization from micrometer-sized polystyrene (PS) seed particles and G2-Vi dendrimers. As an independent 0D microreactor, such dendrimer-functionalized microsphere latices bearing abundant thioether anchor sites can capture guest metal ion components, followed by the introduction of chalcogenides, and hence the in situ generation of higher-uptake NCs was realized. Furthermore, the as-obtained NC–latex hybrids from 0D microreactors were directly self-assembled into large-scale ordered colloidal arrays with uniform fluorescence. Additionally, compact assemblies from the Cd2+-loaded dendrimer-functionalized microspheres were constructed and were employed as a large-scale 2D reactor. An on-demand fluorescence pattern was freely and quickly displayed via a reaction-induce-response process by screen stencil oriented printing.

Interfacial synthesis of SnSe quantum dots for sensitized solar cells

A new interfacial synthesis of colloidal SnSe quantum dots (QDs) was realized with use of common precursors under a moderate temperature (95 °C). SnSe QD-sensitized solar cells were fabricated to show an improved power conversion efficiency (>5 times) with a high fill factor of 0.71.

Interface-spawned NiSe quantum dots: preparation, photoluminescence properties and applications

We report herein the first interfacial synthesis of photoluminescent NiSe QDs and their evolution towards excitation-dependent multicolour hybrid QDs after solvothermal treatment. We demonstrate that tri-n-octylphosphine (TOP), a very commonly used ligand for the synthesis of QDs, would pyrolyze and generate fluorescent carbon dots (CDs), which is responsible for the asymmetrical and bimodal emission of QDs but has been neglected before. Also described is the application of these QDs for multicolour fluorescent patterns with high uniformity.

Generation of a carbon dots/ammonium persulfate redox initiator couple for free radical frontal polymerization

We report a new redox initiator couple of ammonium persulfate (APS)/carbon dots (CDs) with high initiation efficiency used in frontal polymerization (FP). The CDs also served as fluorescent reagents, and had good dispersion and a relatively high absolute quantum yield (>60%). The initiation efficiency and possible mechanism of CDs/peroxydisulfate (S2O82−) initiators were investigated. The electron transfer between the CDs and S2O82− made decomposition of the latter into free radicals easier. Besides, electron transfer occurred between the CDs and vinyl monomers, prompting the CDs to be applied to initiate monomers alone. Therefore, the combined effects of the CDs and APS made vinyl monomers more prone to be triggered in FP, thereby lowering the reaction temperature considerably. This research might provide a promising avenue to discover other polymerization initiators with high efficiency for the synthesis of versatile materials.

Recognition of Latent Fingerprints and Ink-Free Printing Derived from Interfacial Segregation of Carbon Dots

Carbon dots (CDs) have attracted increasing interest in recent years owing to their desirable properties. Despite the availability of diverse elaborate CDs, the function and application of CDs are far to be fully exploited. Here, biomass-derived carbon dots dispersed in a polymer matrix are found to behave as ink-free patterned substrates, which are demonstrated to be useful for nondestructive collection and recognition of latent fingerprints (LFPs), as well as printing. The coating of CD/poly(vinyl alcohol) solution on a LFP yields a flexible transparent film; a stable fluorescent fingerprint with clear ridge details enabling personal identification is formed on this film. Encouragingly, this method can be applied to nondestructively lift and recognize long-timely exposed LFPs from various surfaces. The mechanism for LFP collection and visualization is proposed, which should be ascribed to the interfacial segregation of CDs in the polymer matrix during the film forming process. This mechanism is further validated by and utilized for application of CD/polymer composites in relief printing, intaglio printing, and micro-trace transferring.