This review captures the synthesis, assembly, properties, and applications of copper chalcogenide NCs, which have achieved significant research interest in the last decade due to their compositional and structural versatility. The outstanding functional properties of these materials stems from the relationship between their band structure and defect concentration, including charge carrier concentration and electronic conductivity character, which consequently affects their optoelectronic, optical, and plasmonic properties. This, combined with several metastable crystal phases and stoichiometries and the low energy of formation of defects, makes the reproducible synthesis of these materials, with tunable parameters, remarkable. Further to this, the review captures the progress of the hierarchical assembly of these NCs, which bridges the link between their discrete and collective properties. Their ubiquitous application set has cross-cut energy conversion (photovoltaics, photocatalysis, thermoelectrics), en...

Compound Copper Chalcogenide Nanocrystals

The design of nanoparticles is critical for their efficient use in many applications ranging from biomedicine to sensing and energy. While shape and size are responsible for the properties of the inorganic nanoparticle core, the choice of ligands is of utmost importance for the colloidal stability and function of the nanoparticles. Moreover, the selection of ligands employed in nanoparticle synthesis can determine their final size and shape. Ligands added after nanoparticle synthesis infer both new properties as well as provide enhanced colloidal stability. In this article, we provide a comprehensive review on the role of the ligands with respect to the nanoparticle morphology, stability, and function. We analyze the interaction of nanoparticle surface and ligands with different chemical groups, the types of bonding, the final dispersibility of ligand-coated nanoparticles in complex media, their reactivity, and their performance in biomedicine, photodetectors, photovoltaic devices, light-emitting devices, sensors, memory devices, thermoelectric applications, and catalysis.

The Role of Ligands in the Chemical Synthesis and Applications of Inorganic Nanoparticles.

Technological advances made in constructing high-resolution instrumentation have enabled fabrication of sophisticated counterfeit products As a result, the need to develop novel anti-counterfeiting materials and systems is greatly increasing Accordingly, various functional materials that display distinct chemical, physical as well as optical and electrical properties have been investigated for preventing and detecting counterfeiting In this feature article, we describe recent strategies that have been devised for anti-counterfeiting purposes that focus on colorimetric and fluorometric approaches that are employed in the determination of the authenticity of banknotes, documents, medicine, etc In addition, methods of incorporating organic electronics on banknotes as active authentication tools as well as molecular imaging techniques based on mass spectrometry are briefly described

Recent functional material based approaches to prevent and detect counterfeiting

The development of copper chalcogenide based nanomaterials as promising candidates for sustainable energy materials, due to their environmental compatibility and low toxicity, is presented and discussed in this review. Different solution syntheses have recently been developed for the low-cost preparation of copper chalcogenide nanocrystals, and their unique properties derived from copper deficiencies were investigated with much progress. The notorious compositional instability and defect formation of copper chalcogenide nanocrystals have been healed by forming donor–acceptor pairs in ternary and quaternary chalcogenide based nanocrystals, especially in copper zinc tin sulfides (CZTS). In addition to their use as light absorbers in solar cells, copper chalcogenide nanocrystals have also been utilized in different applications, such as electrode materials in Li ion batteries and high efficiency counter electrodes in dye/quantum dot sensitized solar cells as well as for NIR photothermal therapy. All relate to their unique copper deficiency properties. The copper chalcogenide based nanomaterials are believed to be sustainable materials for future energy applications once the syntheses and property investigations have led to a more complete understanding of their physics.

Development of plasmonic semiconductor nanomaterials with copper chalcogenides for a future with sustainable energy materials

Designer polymer–quantum dot architectures

We report a novel technique for generating polymer fluorescent barcode nanorods by reactive ion etching of polymer multilayer films using nonclose-packed (ncp) colloidal microsphere arrays as masks. The fluorescent polymer multilayer films were spin-coated on a substrate, and ncp microsphere arrays were transferred onto these films. The exposed polymers were then etched away selectively, leaving color-encoded nanorods with well-preserved fluorescent properties. By modifying the spin-coating procedure, the amount of polymer in each layer could be tuned freely, which determined the relative fluorescence intensity of the barcode nanorods. These nanorod arrays can be detached from the substrate to form dispersions of coding materials. Moreover, the shape of the nanorods is controllable according to the different etching speeds of various materials, which also endows the nanorods with shape-encoded characters. This method offers opportunities for the fabrication of novel fluorescent barcodes which can be used ...

Controlled Fabrication of Fluorescent Barcode Nanorods

Detection of highly toxic and bioaccumulative heavy metal ions using fluorescent semiconductor nanoparticles (NPs) has stimulated recent research interests, but the separation of NPs after detection has failed to be achieved. In this paper, fluorescent CdTe NPs-based superparticles (SPs) were fabricated using oil droplets in microemulsion as templates. By controlling the experimental variables, SPs with different fluorescence and composition were obtained. In particular, CdTe/Fe3O4 binary SPs simultaneously exhibited strong fluorescence and magnetism, thus achieving the separation of SPs. These CdTe-based SPs showed an improved detection of Cu2+ and Ag+.

Fabrication of CdTe nanoparticles-based superparticles for an improved detection of Cu2+ and Ag+

A novel microsensor to Hg(2+) was fabricated through self-assembly of aqueous CdTe nanoparticles (NPs). The morphologies of self-assembly mainly included classical dendrites, straight dendrites, and small islands. The formation process of these morphologies was systematically investigated by using the field emission scanning electron microscope, confocal laser scanning microscope, and atom force microscope instruments, etc. The proposed mechanism showed that the dendrite structure was formed via manipulating the short-range van der Waals interaction and long-range electrostatic interaction, which was realized through altering the ligand and concentration of the CdTe NPs. Furthermore, polymers with positive charges were used to effectively control the morphology of the self-assembly as well as improve the property of photoluminescence. These CdTe dendrites were used as microsensors to Hg(2+), which presented the advantages of low cost, quick detection time, high selectivity, and easy operation.

Self-assembly of CdTe nanoparticles into dendrite structure: A microsensor to Hg2+

In this paper, we demonstrated a modified hot-injection method to synthesize high-quality Cu2–xSe nanocrystals (NCs) in liquid paraffin without using the hazardous and unstable alkylphosphines as the ligand of Se. The key of this method is the capability for tuning the reactivity of Se at the stage of formation of Cu2–xSe nuclei. The low reactivity of Se facilitated the decomposition of copper(II) acetylacetonate into Cu2O, whereas the increase of Se reactivity promoted the reaction between Cu and Se. By control of the experimental variables, such as reaction time, Se concentration, reaction temperature, and, particularly, the addition of the noncoordinating solvent of Se, high-quality Cu2–xSe NCs were prepared. The resultant Cu2–xSe NCs possessed an indirect band-gap absorption around 1050 nm, potentially applicable in photovoltaic investigations. As an example, the optoelectronic properties of Cu2–xSe NCs were investigated, which showed a promising increase in photocurrent under AM 1.5 illumination. Bec...

Synthesis of Cu2–xSe Nanocrystals by Tuning the Reactivity of Se

In this paper, we demonstrated a “one-pot” strategy for synthesizing ZnSe nanocrystals (NCs) in liquid paraffin. All materials, including Zn source, Se source, and ligand, were mixed in liquid paraffin beforehand, which avoided the injection of Se source at high temperature. The resultant ZnSe NCs possessed high photoluminescence quantum yields and narrow size distribution. Moreover, the size, shape, and crystal phase of NCs were controllable by altering the experimental variables, such as precursor concentration, Zn:Se molar ratio, and heating rate. Because the raw materials used here were low-cost and environmentally friendly, this “one-pot” synthetic protocol would facilitate the commercial scale synthesis of high-quality ZnSe NCs.

Yang Ning

Papers

Controlled Fabrication of Fluorescent Barcode Nanorods

Fabrication of CdTe nanoparticles-based superparticles for an improved detection of Cu2+ and Ag+

Self-assembly of CdTe nanoparticles into dendrite structure: A microsensor to Hg2+

Synthesis of Cu2–xSe Nanocrystals by Tuning the Reactivity of Se

“One-pot” synthesis and shape control of ZnSe semiconductor nanocrystals in liquid paraffin