Advanced Functional Materials

Solvent-vapor annealing has been successfully employed to increase the degree of order in the self-organization of a perylene-bis(dicarboximide) derivative cast on different substrates from solution (see figure). Upon exposure to tetrahydrofuran vapors, the starting needle-like structures rearrange into millimeter-long fibers, which have a sub-micrometer cross section, with remarkable mass transport at the surface.

A highly shape-selective synthesis of ZnO particles with tunable morphologies and bandgaps (see figure) is realized at temperatures as low as 32 °C by using polyvinylpyrrolidone (PVP) as the nucleation promoter and structure-directing agent.

Submolecularly resolved scanning tunnelling microscopy studies of reactions occurring in confined space (i.e., in two dimensions on a surface, see figure) provide genuine insight into the chemical reaction mechanism and offer new ways to achieve greater control over the reactivity of organic molecules.

The engineering of artificial defects in self-assembled 3D photonic crystals, along with the fabrication of perfect colloidal crystals without unwanted defects will collectively lead to technological applications of self-assembled 3D photonic crystals in the near future. Major recent advances from these authors and an extensive literature review are presented.

The cytotoxicity of micrometer-long gold nanowires is studied as a function of the nanowire aspect ratio and type of surface capping agent. Shorter nanowires are internalized within cells with greater efficiency but are relatively less toxic as compared to their longer counterparts. The nanowires are used to deliver green fluorescence protein expressing plasmids and probe molecules to cells without affecting the viability of the cells.

Solution-processable molecules based on 1,4,5,8-naphthalenetetracarboxylic diimide, which constitutes the central unit, have been synthesized with thiophene substituents of varying chain length attached to the naphthalene core. Organic field-effect transistor devices describe the transfer from n-type to ambipolar character depending on the structure of the molecules.

InGaP quantum dots (QDs) encapsulated with chitosan nanoparticles (see figure) are presented as a robust tool for deep-tissue imaging. These near IR emitting probes can penetrate up to 6 mm into tissue, and results indicate that they can safely be used to perform real-time examinations of a wide variety of organs.

Highly sensitive, low cost, simple nanosensor designs for naked-eye detection of trace levels of toxic metal ions have been successfully developed by the immobilization of chromophore probe molecules into spherical nanosized cavities and surfaces. These chemical nanosensors are reversible and hsow long term stability, and have the potential to serve effectively in on-site field analysis of environmental samples, which eliminates the necessity for instrument-dependent analysis.

A detailed structural study of Bioglass^® using a combination of high-energy X-ray and neutron diffraction, NMR, and reverse Monte Carlo modelling is presented. Bioglass^® is a melt-quenched silicate glass, containing calcium, phosphorus and sodium, with the ability to promote bone regeneration and to fuse to living bone.

The in vivo cellular uptake, degradation and biocompatibility of polyelectrolyte microcapsules produced from alternating dextran sulphate and poly-L-arginine layers on a template of calcium carbonate microparticles is reported. A moderate tissue reaction is observed after subcutaneous injection of polyelectrolyte microcapsules in mice. Within sixteen days after subcutaneous injection, most of the microcapsules are internalized by the cells and start to degrade. The number of polyelectrolyte layers determines the stability of the microcapsules after cellular uptake.

Fourfold oligothienyl-functionalized perylene bisimides are synthesized to produce polymeric networks through electrochemical oxidation. In situ conductance investigation on the resultant films reveals two separate regimes of electrical conductance that can be related to the oligothiophene and perylene bisimide manifolds.

Monodispersed Cu₂O nanocubes with approximate average sizes of 40, 65, 100, 230, and 420 nm have been prepared using a seed-mediated synthesis approach in aqueous solution. The standard deviation of the nanocube sizes in each sample is below 10 %.

Oxygen-deficient BaAl₂O₄, with strong optical absorption in the spectral range from 200 to 2500 nm (see figure), was prepared by the thermal treatment of nanometer-sized BaAl₂O₄ in H₂ flow. The optical absorption is caused by oxygen vacancies existing in the prepared oxygen-deficient BaAl₂O₄ sample.

Solvent-vapor annealing has been successfully employed to increase the degree of order in the self-organization of a perylene-bis(dicarboximide) derivative cast on different substrates from solution (see figure). Upon exposure to tetrahydrofuran vapors, the starting needle-like structures rearrange into millimeter-long fibers, which have a sub-micrometer cross section, with remarkable mass transport at the surface.

A new series of starburst triarylamine fluorophores, showing unique aggregation-induced emission (AIE) upon aggregation or in the solid state, has been synthesized. By changing the substituent groups, the emission of the AIE-active molecules can be tuned from the cyan to the red region. OLEDs using these compounds as non-doped host red emitter and hole transporter have been fabricated. One was tested as a chlorine gas fluorescence solid film chemodosimeter for the first time.

High-efficiency and color-stable blue-light-emitting polymers have been developed by copolymerizing a small amount of blue-emitting dopant into an ultraviolet-emitting polymer host. Because of the efficient energy transfer/charge trapping in these polymers, the devices based on them show excellent device performances with a very stable pure-blue-light emission (see figure).

We analyze effects induced by the incorporation of nitrogen atoms into the backbone of aryl-based molecular wires by comparing the geometrical/organizational parameters, electronic structures, and electrical properties of a new heteroaromatic molecule, 6-(5-pyridin-2-ylpyrazin-2-yl)pyridine-3-thiol (PPPT), and the structurally analogous terphenyl-4-thiol (TPT) system (see figure).

Excited-state energy transfer from spherical green-light-emitting nanocrystals as donor to rod-shaped red-light-emitting nanocrystals as acceptor results in red fluorescence in mixed films. Uniaxial alignment of the quantum rods provides polarized emission, while the absorption remains unpolarized (see figure).

A new copolymer of fluorene with balanced hole and electron mobility is presented and characterized in electronic devices. Bulk heterojunction polymer solar cells with a methanofullerene [6,6]-phenyl-C₆₁-butyric acid methyl ester acceptor also give well-balanced electron and hole mobility, to result in a 3.7% power conversion efficiency.

Hexagonal (left) and cubic (right) phase of NaGdF₄:Eu³⁺ (10 mol %) under broad-band UV excitation (230–300 nm). Oxygen substitution in the cubic lattice leads to a stronger Eu³⁺-emission due to the presence of the Eu³⁺-O^2– charge transfer band in the UV region.

The photoconductivity of solution-cast Zn_1-xMg_xO/poly(3-hexylthiophene) (P3HT) thin films and bilayers is investigated to determine the locus of free charge carrier generation in the bilayer system. Free carrier generation in the bilayers predominantly occurs in the bulk of P3HT, followed by electron injection to the oxide to yield photocurrent in photovoltaic cells (see scheme).

Electropolymerized methyl viologen-imprinted polyphenol on electrodes provides a selective medium for the electrochemical detection of methyl viologen and enables vectorial electron transfer communication. The imprinting process and the selectivity of sensing are driven by π donor–acceptor interactions.

Hybrid films of ZnO and tetrasulfonated nickel phthalocyanine can be electrodeposited within a wide range of phthalocyanine contents just by changing its concentration in the electrodeposition bath, allowing to tune the structural, optical and (photo-)electrical properties of the films.

Iron oxide coated Fe nanocubes are synthesized by thermal decomposition of an iron oleate complex in squalene. More than 90 % of the resultant nanoparticles have a cubic morphology. The nanocubes are in a superparamagnetic state at room temperature, with a low-T magnetic anisotropy about 10 times larger than that of bulk Fe.

A carbon-coated LiTi₂(PO₄)₃/LiMn₂O₄aqueous lithium-ion battery is proposed. It delivers a specific energy of 60 W h kg^–1 based on the total weight of the active material, and also exhibits an excellent cycling stability and rate capability.

Well-crystallized and pure olivine-phase LiFePO₄–1.37 wt % Ag composite thin films with uniform and variable thickness can be deposited on Si/SiO₂/Ti/Pt substrates via a pulsed laser deposition method. The as-deposited cathode films show a superior electrochemical performance (see figure) with a good combination of moderate specific capacity, stable cycling, and most importantly, remarkable tolerance against high rate and over-charging/-discharging.

A highly shape-selective synthesis of ZnO particles with tunable morphologies and bandgaps (see figure) is realized at temperatures as low as 32 °C by using polyvinylpyrrolidone (PVP) as the nucleation promoter and structure-directing agent.

Device layout can affect the determination of donor–acceptor organic solar-cell efficiency. Devices with crossing electrodes and unpatterned conducting layers (see figure) can collect non-negligible current from regions usually not considered as part of the photovoltaic element.

Zeolitic molecular pockets embedded in the walls of the mesoporous material Zeotile-2 (see scheme) impose steric constraints on the adsorption of branched alkanes. These constraints permit separation of linear and branched alkanes via shape selectivity, uniquely combining the properties of mesoporous and microporous materials.

The magnetic and transport properties of homogeneously strained high quality LCMO/STO thin films are analyzed. Soft X-ray absorption spectroscopy at the O K-edge shows that interfacial strain due to substrate/film mismatch is strong enough to split the e_g and t_2g levels close to the film/substrate interface, promoting selective orbital occupancy with charge localization, favoring the appearance of an orbital glass insulating phase. Concomitantly, we observe an increase of the Mn⁴⁺ concentration close to this interface.

Hybrid organic-inorganic thin films exhibiting patterned structuring on the nanometer scale have been prepared via the sol-gel process assisted by spin coating. A self-templating process is demonstrated via atomic force and transmission electron microscopy showing the formation of nanometer size aggregates consisting of interconnected spherulates under acidic conditions and of assembled fibers under basic conditions.

Nearly monodisperse, spherical nanoparticles of Ni₂P with high surface areas have been prepared by arrested precipitation, and their surfaces have been modified by ligand removal and ligand exchange. The activity towards hydrodesulfurization of thiophene and the phase stability of the nanoparticles was found to be a sensitive function of the surface chemistry. In all cases, the Ni₂P nanoparticles are more active than bulk materials.

A novel 3D cement direct printing process is established to manufacture a variety of calcium phosphate bone graft substitutes with programmed macropore architecture at room temperature (see figure). Here we compare the in vivo dissolution of CaHPO₄·2H₂0, brushite, with that of the anhydrous form monetite for the first time. Monetite was found to be approximately twice more soluble in vivo and, unlike brushite, did not convert to insoluble HA.

A microwave-induced method for controlled purification of single-walled carbon nanotubes by removing residual metal catalysts and non-tubular carbonaceous matter is presented. The method employs weak acids and chelating agents to remove these impurities. Consequently, there is no detectable damage or functionalization of the nanotube sidewalls.