Self-organization In Thin Films Research Articles

Influence of Backbone Ladderization and Side Chain Variation on the Orientation of Diketopyrrolopyrrole-Based Donor-Acceptor Copolymers.

Ladder polymers with poly(diketopyrrolopyrrole) (DPP) moieties have recently attracted enormous interest for a large variety of opto-electronic applications. Since the rigidity of the backbone increases with ladderization, a strong influence on the self-organization of thin films is expected. We study the molecular orientation of DPP-based ladder polymers in about 50 nm thin films using polarization modulation-infrared reflection-absorption spectroscopy (PM-IRRAS). Exemplarily, for one polymer, the orientation in thicker films is qualitatively investigated by infrared spectroscopy in transmission. Further, this method allows us to rule out the effects of a possible azimuthal ordering, which would affect the analysis of the orientation by PM-IRRAS. For all polymers, the long axis of the polymer backbone is preferentially oriented parallel to the substrate surface, pointing to a high degree of ordering. It is suggested that the choice of the side chains might be a promising way to tune for face-on and edge-on orientations. The exemplarily performed investigation of interface properties on substrates with different work functions suggests that the choice of the side chains has a minor effect on the interfacial electronic interface structure.

Dielectric layer of printed circuit boards formation using dendrimer morphology polyaluminosilicates

Aluminosilicates with different molecular weights have been synthesized. A composite material based on aluminosilicates and highly dispersed filler powders with various filling degrees has been obtained. Viscosity values of the aluminosilicates with different molecular weights and composites based on them with highly dispersed AlO(OH) powders have been studied. The processes of mechanochemical mixing of the aluminosilicates with fillers have been studied. The interrelation between the molecular architecture of branched polyaluminosilicates functionalized by reactive groups and their self-organization in thin films and layers has been revealed. Samples with applied dielectric layers and coatings on aluminum bases have been produced. Thermal conductivity of the developed dielectric layers used in printed circuit boards on metal bases has been measured.

Electronic structure and self-organization properties of low band gap polymers: The effect of the introduction of additional thiophene moieties

An approach to improve the efficiency of donor-acceptor based bulk heterojunction (BHJ) organic solar cells is the use of low band gap (LBG) polymers as donor materials. The properties of these materials in BHJ solar cells are strongly influenced by their morphology and ability for self-organization in thin-films. We studied for two related polymer pairs the influence of the introduction of additional (hexyl-) thiophene moieties on both the electronic structure and ability for self-organization in thin films using Ultraviolet photoelectron spectroscopy (UPS) and Near-Edge X-Ray Absorption Fine Structure spectroscopy (NEXAFS). In addition, the influence of mixing with PCBM and post-processing annealing on the molecular orientation is investigated. We find that the introduction of additional (hexyl-) thiophene moieties in the polymer structure does not affect significantly the electronic structure of the polymers in thin films, but has a strong impact on their self-organization properties and consequently affects their behavior in devices.

Self-organization in thin films of nanocomposite silicon-carbon

In order to develop new materials for lithium batteries, thin films on based on Si/C nanocomposite have been synthesized and investigated. These films are produced by the consequent magnetron deposition of nanosize layers of carbon and silicon onto metallic substrates at under room temperature. The thickness of each layer is 1–6 nm, and the total thickness of the films varies from 100 to 400 nm. The film structure is examined by energy dispersive X-ray analysis (EDAX), optical and Raman spectroscopy, scanning electron microscopy (SEM), and atomic force microscopy (AFM). It is shown that the films are not layer structures as was expected; they are fractal disordered structures characterized by three scale levels: a matrix that consists of 20–30-nm particles, the aggregates (200 nm) stabilized in this matrix, and tiny particles 3–5 nm in size which are incorporated in large aggregates. The structure of the aggregates is analyzed by computer simulation. The values of fractal dimensionality are determined, and the ways of fractal structure formation and development are considered.

Self Organization in Thin Films of a Substituted Perylene Imide with a Twisted Aromatic Core

ABSTRACTThe aromatic core of perylene bisimides can be twisted by chemical substitution with chlorine in the bay-position. An example for this strategy is 1,6,7,10-tetra-chloro-N,N'-dimethyl-perylene-tetracarboxylic-bisimide, Cl4MePTCDI. This twisting leads to a decrease in directed intermolecular interactions, which causes a decrease in the electronic coupling of the molecules, interesting to be investigated in thin films of this molecular semiconductor. An amorphous solid phase was formed by physical vapor deposition. This amorphous phase showed the tendency to crystallize under ambient conditions as apparent von optical microscopy at the films. The crystallized phase was investigated by atomic force microscopy AFM and optical methods, where a formation of weak excimers was found.

Synthesis of Carboxylated Monodisperse Latexes and Their Self-Organization in Thin Films

The capability of carboxylated latexes of poly(methyl methacrylate) and copolymers of styrene with glycidyl methacrylate or methacrylic acid for self-organization in thin films was studied in relation to the compositions of the dispersion medium and polymer and to the latex particle size.

Self-Organization in Thin Films of Liquid Crystalline Perylene Diimides

A family of liquid crystalline organic semiconductors based on perylene-3,4,9,10-tetracarboxyldiimide is introduced. The thermal transitions, self-organizing behavior, and change in photophysical properties upon self-organization of one member of the family are described. Red, polycrystalline thin films of spin-coated N,N‘-bis[3-[1,3-bis[2-(2-methoxyethoxy)ethoxy]-2-propoxy]propyl] perylene-3,4,9,10-tetracarboxyldiimide spontaneously form a highly crystalline black phase after about 24 h. The quantum yield for fluorescence from the black phase is enhanced 7-fold, and the width (fwhm) of the emission band is decreased by more than a factor of 2, with respect to the red phase. The self-organization process appears to decrease spontaneously both the energetic disorder and the density of exciton quenching sites in the film.