Constructing Functional Mesostructured Materials from Colloidal Nanocrystal Building Blocks

A review. The authors describe how recent insights into colloidal nanocrystal (NC) surface chem. have fueled dramatic progress in functional mesostructures. The simplest mesoscale assemblies considered are networks of NCs constructed by in situ replacement of their bulky, insulating surface ligands with small mols. Optical and electrochem. applications of these mesoscale materials are considered

Preparation of organometallic uracil-analogue Fischer carbenecomplexes: Comparative study of conventional heatingvs microwave irradiation

Mono and disubstituted ureas react with alkynyl Fischer carbene complexes to give mono and di N,N-substituted organometallic uracil analogues. An optimization of the process using different starting metal carbene complexes and variously substituted ureas under conventional heating (with and without solvent) and microwave irradiation techniques is reported. The synthesis of the metal–carbene analog of the commercially available dimethyl uracil is reported

Tunable Infrared Absorption and Visible Transparency of Colloidal Aluminum-Doped Zinc Oxide Nanocrystals

Plasmonic nanocrystals were attracting a lot of attention both for fundamental studies and different applications, from sensing to imaging and optoelectronic devices. Transparent conductive oxides represent an interesting class of plasmonic materials in addn. to metals and vacancy-doped semiconductor quantum dots. A rational synthetic strategy of high-quality colloidal Al-doped Zn oxide nanocrystals is reported. The presence of substitutional Al in the Zn oxide lattice accompanied by the generation of free electrons is proved by tunable surface plasmon absorption in the IR region both in soln. and in thin films

Nanocrystal-based active layers with tailored interfaces and architectures for advanced energy applications

The properties of tasked nanocrystals in energy-related devices are strongly dependent on the presence and chem. nature of ligands at their surface, and the architectures they assume in electroactive layers. Here we will describe an exceptionally versatile class of reagents for native ligand stripping of carboxylate-, phosphonate- and amine- passivated nanocrystals, resulting in either bare or BF4-/DMF-passivated surfaces depending on the material used. These reagents were effective both for thin films of nanocrystals as well as their dispersions. Significantly, no etching of the nanocrystals was obsd. We will also show that dispersions of ligand stripped nanocrystals are useful as nanoinks and are amenable to architecturing at the mesoscale using suitable macromol. tamplating agents that make particular use of specific and dynamic mol. interactions at the nanocrystal surface. Structured electroactive layers as such are poised to overcome challenges assocd. with electrochem. reactions occurring at accessible interfaces

Modulation of Carrier Type in Nanocrystal-in-Matrix Composites by Interfacial Doping

Inorganic nanocomposites synthesized by combination of colloidal nanocrystals (NCs) and inorganic clusters have recently emerged as new materials with novel and unique functionalities. Much of the demonstrated promise of nanocomposites derives from the unique interactions between NC and matrix components - this generates new material properties, which direct unique transport behavior in the overall solid or nanocomposite - be it mass, charge, or heat. While measured empirically, it has remained largely impossible to take an a priori look at material properties and use those as a guideline to design desired transport behavior. Fundamentally, this is because the structural and electronic changes manifest at those interfaces have remained hidden from examination. Here, we provide experimental evidence that transport behavior in nanocrystal-in-matrix (NIM) composites is dictated primarily by interfacial charge transfer associated with electronic and structural reconstructions as the composite forms. Our approach building continuous composite superlattices serves as a starting point for systematic probing of the nanointerface of NIM composites via ultrathin films. A combination of field effect transistor device characterization and photoemission spectroscopy reveals the systematic dependence of the polarity of charge transfer on the selection of matrix materials in NIM composites. We use this insight to combine, by design, different components to tune the carrier type in NIM composites