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The magnetic fields in substituted hexabenzocoronenes (HBC) are effective for producing oriented films of discotic liquid-crystalline materials, which allows the investigation of structure-property relationships in magnetically aligned films formed in field-effect transistor structures in a noninvasive, contact-free way. Since the magnetic field alignment is applicable to a wide range of self-assembled systems, this approach can be used for optimizing the properties of functional materials.

Author(s): Natalie Stutzmann [1]; Theo A. Tervoort (corresponding author) [1]; Kees Bastiaansen [1, 2]; Paul Smith (corresponding author) [1] The ability to micropattern materials is of great importance for manufacturing [...]

The chemical structures designed by inserting decoupling spacers between a trisfunctionalized benzene core and the three azobenzene moieties, as well as adding polar end groups to the latter that allow formation of both an amorphous and a liquid-crystalline phase. The obtained nonpolymeric, azobenzene-containing compounds could find valuable application for fabrication of stable holographic volume gratings.

Atomic force microscopy reveals that control of thin film morphology by respective self-assembly of p-type oligo(p-phenylenevinylene)s (OPV)s and n-type perylenebisimides (PBI)s in solution prior to processing results in film architectures which constitute uniform rodlike domains. Such films show improved charge-carrier mobility when compared to films processed from molecular dissolved molecules, and ampipolar field-effect transistors constructed from dyad complexes of OPVs and PBIs exhibit independent pathways for charge transport.

An efficient synthetic route to the first high molecular weight poly(3-hexylthiophene)-Polyethylene (P3HT-PE) block copolymer using ruthenium-catalyzed ring-opening metathesis polymerization (ROMP) is described. The novel P3Ht-PE block copolymers would allow exploration of new functional morphologies and expand the processing and structural toolbox for conjugated materials.

A surface X-ray diffraction study is presented showing that highly ordered and uniaxially aligned hexa(3,7-dimethyl-octanyl)hexa-peri-hexabenzocoronene (HBC-C8,2) films can be fabricated by crystalization from solution onto friction-transferred poly(tetrafluoroethylene) (PTFE) layers. A quasi-2D epitaxial growth mechanism with a grapho-epitaxial component for one of the three phases explains the formation of the three rotational HBC-C8, 2 variants.

Blends and other multicomponent systems are used in various polymer applications to meet multiple requirements that cannot be fulfilled by a single material. In polymer optoelectronic devices it is often desirable to combine the semiconducting properties of the conjugated species with the excellent mechanical properties of certain commodity polymers. Here we investigate bicomponent blends comprising semicrystalline regioregular poly(3-hexylthiophene) and selected semicrystalline commodity polymers, and show that, owing to a highly favourable, crystallization-induced phase segregation of the two components, during which the semiconductor is predominantly expelled to the surfaces of cast films, we can obtain vertically stratified structures in a one-step process. Incorporating these as active layers in polymer field-effect transistors, we find that the concentration of the semiconductor can be reduced to values as low as 3 wt% without any degradation in device performance. This is in stark contrast to blends containing an amorphous insulating polymer, for which significant reduction in electrical performance was reported. Crystalline–crystalline/semiconducting–insulating multicomponent systems offer expanded flexibility for realizing high-performance semiconducting architectures at drastically reduced materials cost with improved mechanical properties and environmental stability, without the need to design all performance requirements into the active semiconducting polymer itself. [ABSTRACT FROM AUTHOR]

Electronic devices based on single crystals of organic semiconductors provide powerful means for studying intrinsic charge-transport phenomena and their fundamental electronic limits. However, for technological exploitation, it is imperative not to be confined to the tedious growth and cumbersome manipulation of molecular crystals—which generally show notoriously poor mechanical properties—but to be able to process such materials into robust architectures by simple and efficient means. Here, we advance a general route for facile fabrication of thin-film devices from solution. The key beneficial feature of our process—and the principal difference from existing vapour deposition and solution-processing schemes—is the incorporation of a glass-inducing diluent that enables controlled crystallization from an initial vitreous state of the organic semiconductor, formed in a selected area of the phase diagram of the two constituents. We find that the vitrifying diluent does not adversely affect device performance. Indeed, our environmentally stable, discrete rubrene-based transistors rival amorphous silicon devices, reaching saturated mobilities of up to 0.7 cm2 V−1 s−1, ON–OFF ratios of ≥106 and subthreshold slopes as steep as 0.5 V per decade. A nearly temperature-independent device mobility, indicative of a high crystalline quality of our solution-processed, rubrene-based films, corroborates these findings. Inverter and ring-oscillator structures are also demonstrated. [ABSTRACT FROM AUTHOR]

Reports on the generation of patterned ceramic surfaces with a feature resolution in the micrometer range by casting aqueous suspensions of high solids loadings onto nonporous polymer molds. Fabrication of high-quality line patterns for alumina, zirconia, cerium gadolinium oxide and tin oxide powders.

The article reports on a simple, rapid film-deposition technique that allows deposited molecules to self-organize into complex architectures with high charge-carrier mobilities where required within a low-charge-carrier-mobility surround that provides electrical insulation for individual devices. It describes the key features and advantages of organic field-effect transistors.

The semiconductors [Pt(NH2dmoc)4][PtCl4], where dmoc denotes (S)-3,7-dimethyloctyl, and [Pt(NH2eh)4][PtCl4], where eh is (R)-2-ethylhexyl, are soluble quasi-one-dimensional compounds with a backbone of linearly arranged platinum atoms. Uniaxially oriented films of those metal complexes of approximately 0.1 μm thickness were deposited from solution on quartz glass slides covered with a friction-deposited orientation layer of approximately 40 nm poly(tetrafluoroethylene) (PTFE). UV/vis spectra recorded with polarized light as well as electron diffraction patterns of [Pt(NH2dmoc)4][PtCl4] indicated that the films were highly ordered, the platinum arrays oriented parallel to the orientation direction of the PTFE molecules. As a consequence, the films exhibited a pronounced anisotropy, among other characteristics, in the electric conductivity, which is of potential use in electronic devices. [Copyright &y& Elsevier]