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Although perovskite nanocrystals have attracted considerable interests as emerging semiconductors in optoelectronic devices, design and fabrication of a deformable structure with high stability and flexibility while meeting the charge transport requirements remain a huge challenge. Herein, a combined soft‐hard strategy is demonstrated to fabricate intrinsically flexible all‐inorganic perovskite layers for photodetection via ligand cross‐linking. Perfluorodecyltrichlorosilane (FDTS) is employed as the capping ligand and passivating agent bound to the CsPbBr3 surface via Pb‐F and Br‐F interactions. The SiCl head groups of FDTS are hydrolyzed to produce SiOH groups which subsequently condense to form the SiOSi network. The CsPbBr3@FDTS nanocrystals (NCs) are monodispersed cubes with an average particle size of 13.03 nm and exhibit excellent optical stability. Furthermore, the residual hydroxyl groups on the surface of the CsPbBr3@FDTS render the NCs tightly packed and cross‐linked to each other to form a dense and elastic CsPbBr3@FDTS film with soft and hard components. The photodetector based on the flexible CsPbBr3@FDTS film exhibits outstanding mechanical flexibility and robust stability after 5000 bending cycles. [ABSTRACT FROM AUTHOR]

This communication describes a novel low-dimensional nanohybrid structure consisting of all-inorganic perovskite nanocrystals (NCs) growing in situ on two-dimensional (2D) black phosphorus (BP) nanosheets. Such a nanohybrid structure promises synergetic properties by combining the respective strengths of perovskite materials and BP, which opens new opportunities for next-generation optoelectronic devices. [ABSTRACT FROM AUTHOR]

Abstract: Heterostructures composed of two‐dimensional black phosphorus (2D BP) with unique physical/chemical properties are of great interest. Herein, we report a simple solvothermal method to synthesize in‐plane BP/Co2P heterostructures for electrocatalysis. By using the reactive edge defects of the BP nanosheets as the initial sites, Co2P nanocrystals are selectively grown on the BP edges to form the in‐plane BP/Co2P heterostructures. Owing to disposition on the original defects of BP, Co2P improves the conductivity and offers more active electrocatalytic sites, so that the BP/Co2P nanosheets exhibit better and more stable electrocatalytic activities in the hydrogen evolution and oxygen evolution reactions. Our work not only extends the application of BP to electrochemistry, but also provides a new idea to improve the performance of BP by utilization of defects. Furthermore, this strategy can be extended to produce other BP heterostructures to expand the corresponding applications. [ABSTRACT FROM AUTHOR]

Black phosphorus quantum dots (BPQDs) were synthesized using a liquid exfoliation method that combined probe sonication and bath sonication. With a lateral size of approximately 2.6 nm and a thickness of about 1.5 nm, the ultrasmall BPQDs exhibited an excellent NIR photothermal performance with a large extinction coefficient of 14.8 Lg−1 cm−1 at 808 nm, a photothermal conversion efficiency of 28.4 %, as well as good photostability. After PEG conjugation, the BPQDs showed enhanced stability in physiological medium, and there was no observable toxicity to different types of cells. NIR photoexcitation of the BPQDs in the presence of C6 and MCF7 cancer cells led to significant cell death, suggesting that the nanoparticles have large potential as photothermal agents. [ABSTRACT FROM AUTHOR]

CdMnTe ( x = 0, 0.1, 0.2) nanocrystals have been synthesized by mechanical alloying (MA) Cd, Mn, and Se elemental powders. XRD patterns and HRTEM images confirmed the formation of cubic CdMnTe nanocrystals. All the diffraction peaks from elemental Cd, Mn, and Te powders disappeared completely in those XRD patterns of as-milled CdMnTe nanocrystals for more than 20 h. When the MA process was carried out for 40 h, typical zinc blende structure diffraction mode was exhibited in the XRD pattern. Subsequently, capping the surface of as-milled CdMnTe nanocrystals with long chain trioctylphosphine/trioctylphosphine oxide/nitric acid (TOP/TOPO/NA) molecules has achieved colorful dispersion solution, which shows similar optical properties to those CdTe nanocrystals prepared by wet chemical process. The grain size is within the range of 2-8 nm for the capped CdMnTe nanocrystals being ball milled for 40 h. The PL excitation peak red shifts to longer wavelength side with increasing Mn concentration. Pure CdTe nanocrystals show ferromagnetism behavior at room temperature, the saturation magnetization value and magnetic hysteresis loop increase with the content of substituting Mn ions within the CdMnTe nanocrystals. [ABSTRACT FROM AUTHOR]

We developed a new fluorescent nanocomposite by using a layer-by-layer approach to link NaYF:Ce,Tb rare-earth (RE) nanocrystals and CdSe/ZnSe semiconductor quantum dots (QDs) with opposite charges. Under ultraviolet light excitation, the nanocomposites exhibited both the green Tb emission centered at 550 nm, and the red QD emission at 650 nm. Sensing applications showed that the red QD emission was quenched by trace amount of Cu (or Ag) ions due to the ion displacement mechanism, while the green RE emission kept constant. Thus, the nanocomposites with the decreased QD/RE emission intensity ratio and changed fluorescence output color provided a visible 'indicator' to detect metal ions quantificationally. In comparison with single emission materials, the dual emission nanocomposites can be a more reliable probe for various sensing applications. [ABSTRACT FROM AUTHOR]

Semiconductor nanocrystals (SNCs) doped with Mn2+ and Cu2+ ions (ZnSe:Mn, ZnSe:Mn/CdSe, and ZnSe:Cu) were synthesized and their nonlinear absorption properties were investigated using the typical open-aperture Z-scan technique. A reversal from reverse saturable absorption (RSA) to saturable absorption (SA) was observed in the ZnSe:Mn SNCs. In contrast, the SA signals were largely suppressed and only RSA signals were measured in the ZnSe:Mn/CdSe and ZnSe:Cu SNCs. These different nonlinear absorption properties implied strong interactions between the excited excitons and impurity ions, which agreed well with the analysis performed by the theory model of the exciton transition in the energy structures. The nonlinearities of the doped SNCs could be controllably tuned by the integration of different doped ions and host SNCs. This strategy shows promise for extensive potential applications in optical limiting and switching. [ABSTRACT FROM AUTHOR]

An image is presented of the synthesis of black phosphorus quantum dots.

• A simple in situ photopolymerization technique to produce homogeneous perovskite-silicone elastomer composites. • The fabrication process is completed in 5 min under UV irradiation at ambient conditions. • The mechanical property of composite is tunable from rigid to elastic. • The superb properties of composite enable optical visualization tracking for magnetically driven soft robots. Metal halide perovskite (CsPbX 3 , X = Cl, Br, I) nanocrystals (MHP NCs) have been widely investigated for a variety of optoelectronic applications due to their superior photophysical characteristics. However, the inherent poor stability has limited broad applications. Herein, a facile in situ photopolymerization strategy using MHP NCs as photo-initiators is designed to fabricate homogeneous perovskite-silicone composites with outstanding stability, flexibility, and scalability. The fabrication process is completed upon exposure to 30 W ultraviolet light for 5 min under ambient conditions without additional protections and additives. The composites have exceptional stability in air and can even withstand harsh conditions, such as a basic pH of 13 for six months. The mechanical properties of composites are tunable from rigid to elastic by regulating the composition, ratios of polymerization monomers, and reaction time. Their superb properties enable optical visualization tracking for magnetically driven soft robots. This convenient and effective approach opens a new pathway for future applications in optical tracking, soft displays, biological detection, and bioimaging of perovskite nanocrystals. [ABSTRACT FROM AUTHOR]

This paper describes a facile method for synthesis of Au–AgCdSe hybrid nanorods with controlled morphologies and spatial distributions. The synthesis involved deposition of Ag tips at the ends of Au nanorod seeds, followed by selenization of the Ag tips and overgrowth of CdSe on these sites. By simply manipulating the pH value of the system, the AgCdSe could selectively grow at one end, at both the ends or on the side surface of a Au nanorod, generating a mike-like, dumbbell-like, or toothbrush-like hybrid nanorod, respectively. These three types of Au–AgCdSe hybrid nanorods displayed distinct localized surface plasmon resonance and photoluminescence properties, demonstrating an effective pathway for maneuvering the optical properties of nanocrystals. [ABSTRACT FROM AUTHOR]

Abstract: A surfactant-free aqueous solution route has been established for the synthesis of LaF3:Ln 3+/LaF3 core/shell nanocrystals (Ln=Ce, Tb, Nd) heated at 75°C at ambient pressure. All the as-prepared nanocrystals with spherical shape have an average size around 20nm, and consist of well crystallized hexagonal phases. The X-ray photoelectron spectra was used to confirm that the LaF3 shells have coated the LaF3:Ce3+, Tb3+ cores. Compared with that of the original cores under the same conditions, the emission intensity of the LaF3:Ce3+, Tb3+/LaF3 and LaF3:Nd3+/LaF3 core/shell nanocrystals increased significantly of 120% and 60%, respectively. The quantum yield of the LaF3:Ce3+, Tb3+/LaF3 core/shell nanocrystals reached about 27% in aqueous solution. These results indicate that a significant reduction of the quenching from the surface of the core nanocrystals can be obtained by the synthesis of the core/shell structures, and this method can provide more desirable lanthanide-doped nanocrystals for potential biological applications. [Copyright &y& Elsevier]

MnF2 nanocrystals co-doped with Yb3+/Er3+ ions were synthesized via a polyethyleneimine (PEI)-based method. These nanocrystals exhibited unique red up-converted fluorescence at 660nm under excitation at 970nm, because Mn2+ ions in the host efficiently induced an energy transfer (4S3/2→4F9/2) of Er3+. Considering that the light of wavelength 600–1100nm has a high penetration depth in tissues, such PEI-coated up-converted nanocrystals have the potential to be good candidates for deep tissue imaging. [Copyright &y& Elsevier]