Organic Optocoupler with Simple Construction as an Effective Linear Current Transceiver.

In this study, it is shown that an efficient organic optocoupler (OPC) can be fabricated using commercially available and solution-processable organic semiconductors. The transmitter is a single-active-layer organic light-emitting diode (OLED) made from a well-known polyparavinylene derivative, Super Yellow. The receiver is an organic light-emitting diode (OLSD) with a single active layer consisting of a mixture of the polymer donor PTB7-Th and the low-molecular-weight acceptor ITIC; the receiver operates without an applied reverse voltage.

Bottlebrush Polymers for Articular Joint Lubrication: Influence of Anchoring Group Chemistry on Lubrication Properties.

The role of carboxylic, aldehyde, or epoxide groups incorporated into bottlebrush macromolecules as anchoring blocks (or cartilage-binding blocks) is investigated by measuring their lubricating properties and cartilage-binding effectiveness. Mica modified with amine groups is used to mimic the cartilage surface, while bottlebrush polymers functionalized with carboxylic, aldehyde, or epoxide groups played the role of the lubricant interacting with the cartilage surface. We demonstrate that bottlebrushes with anchoring blocks effectively reduce the friction coefficient on modified surfaces by 75-95% compared to unmodified mica.

Molecular Dynamics and Structure of Poly(Methyl Methacrylate) Chains Grafted from Barium Titanate Nanoparticles.

Core-shell nanocomposites comprising barium titanate, BaTiO (BTO), and poly(methyl methacrylate) (PMMA) chains grafted from its surface with varied grafting densities were prepared. BTO nanocrystals are high-k inorganic materials, and the obtained nanocomposites exhibit enhanced dielectric permittivity, as compared to neat PMMA, and a relatively low level of loss tangent in a wide range of frequencies. The impact of the molecular dynamics, structure, and interactions of the BTO surface on the polymer chains was investigated.

Gold Nanoparticles as Effective ion Traps in Poly(dimethylsiloxane) Cross-Linked by Metal-Ligand Coordination.

At this time, the development of advanced elastic dielectric materials for use in organic devices, particularly in organic field-effect transistors, is of considerable interest to the scientific community. In the present work, flexible poly(dimethylsiloxane) (PDMS) specimens cross-linked by means of ZnCl-bipyridine coordination with an addition of 0.001 wt.

Self-Aligned Bilayers for Flexible Free-Standing Organic Field-Effect Transistors.

Free-standing and flexible field-effect transistors based on 6,13-bis(triisopropylsilylethynyl)-pentacene (TIPS-pentacene)/polystyrene bilayers are obtained by well-controlled phase separation of both components. The phase separation is induced by solvent vapor annealing of initially amorphous blend films, leading to crystallization of TIPS-pentacene as the top layer. The crystallinity and blend morphology strongly depend on the molecular weight of polystyrene, and under optimized conditions, distinct phase separation with a well-defined and trap-free interface between both fractions is achieved.

Surface-enhanced Raman scattering of water in aqueous dispersions of silver nanoparticles.

The resonance Raman effect (RRE) is a phenomenon which results in a strong selective enhancement of Raman signals from the samples. Previous studies showed that the RRE in liquid water directly corresponds to its supramolecular structure. It was also reported that the electric-field-induced orientation of water molecules on the electrode surface results in the surface-enhanced Raman scattering (SERS) effect.

Effects of Counter Anions on AC and DC Electrical Conductivity in Poly(Dimethylsiloxane) Crosslinked by Metal-Ligand Coordination.

There is an urgent need for the development of elastic dielectric materials for flexible organic field effect transistors (OFETs). In this work, detailed analysis of the AC and DC electrical conductivity of a series of flexible poly(dimethylsiloxane) (PDMS) polymers crosslinked by metal-ligand coordination in comparison to neat PDMS was performed for the first time by means of broadband dielectric spectroscopy. The ligand was 2,2-bipyridine-4,4-dicarboxylic amide, and Ni, Mn, and Zn were introduced for Cl, Br, and I salts.

Inkjet Printing of an Electron Injection Layer: New Role of Cesium Carbonate Interlayer in Polymer OLEDs.

Among solution-processable techniques, inkjet printing is a potential method for manufacturing low-cost and high-resolution polymer organic light-emitting diodes (PLEDs) for displays/solid-state lighting applications. Herein, we demonstrate use of the inkjet printed cesium carbonate (CsCO) film as an electron injection interlayer. We have elaborated the CsCO ink using an alcohol-based solvent for the industrial-grade printhead.

Geometry Control of Source/Drain Electrodes in Organic Field-Effect Transistors by Electrohydrodynamic Inkjet Printing.

In this work we study the influence of dielectric surface and process parameters on the geometry and electrical properties of silver electrodes obtained by electrohydrodynamic inkjet printing. The cross-section and thickness of printed silver tracks are optimized to achieve a high conductivity. Silver overprints with cross-section larger than 4 μm and thickness larger than 90 nm exhibit the lowest resistivity.

Effect of β-Ketoiminato Ancillary Ligand Modification on Emissive Properties of New Iridium Complexes.

A series of new bis(benzo[]quinolinato) Ir(III) complexes with modified β-ketoiminato ancillary ligands were synthesized, and their electrochemical, photophysical properties were determined with the support of theoretical calculations. Moreover, all the synthesized heteroleptic Ir(III) complexes were examined as dopants of the host-guest type emissive layers in solution-processed phosphorescent organic light emitting diodes (PhOLEDs) of a simple structure. As expected on the basis of voltammetry measurements as well as DFT calculations, all the compounds appeared to be green emitters.

Inkjet Printing of Super Yellow: Ink Formulation, Film Optimization, OLEDs Fabrication, and Transient Electroluminescence.

Inkjet printing technique allows manufacturing low cost organic light emitting diodes (OLEDs) in ambient conditions. The above approach enables upscaling of the OLEDs fabrication process which, as a result, would become faster than conventionally used vacuum based processing techniques. In this work, we use the inkjet printing technique to investigate the formation of thin active layers of well-known light emitting polymer material: Super Yellow (poly(para-phenylene vinylene) copolymer).

Realizing 20% External Quantum Efficiency in Electroluminescence with Efficient Thermally Activated Delayed Fluorescence from an Exciplex.

The investigation of nondoped exciplex blends of 2,4,6-tris[3-(diphenylphosphinyl)phenyl]-1,3,5-triazine (PO-T2T), working as the one-electron acceptor molecule, with different electron donors is reported. The emissions of these exciplexes span from the blue to orange-red regions, showing clear contribution from thermally activated delayed fluorescence (TADF) and delayed fluorescence originated from nongeminate recombination of charge carriers created by the dissociation of optically generated exciplexes. We focus our studies on the properties of TADF in these systems, covering in particular the physical meaning of the different transient components observed in their luminescence decays.

Slot-Die Coating of Double Polymer Layers for the Fabrication of Organic Light Emitting Diodes.

This study presents the slot-die coating process of two layers of organic materials for the fabrication of organic light emitting diodes (OLEDs). Poly(3,4-ethylenedioxythiophene) polystyrene sulfonate (PEDOT:PSS), which is commonly used in OLEDs and in organic photovoltaic devices as the hole injection layer (HIL), has been deposited via slot-die coating. Uniform films of PEDOT:PSS were obtained after optimizing the slot-die processing parameters: substrate temperature, coating speed, and ink flow rate.

Nonhalogenated Solvent-Processed All-Polymer Solar Cells over 7.4% Efficiency from Quinoxaline-Based Polymers.

Two conjugated polymers, with different side chains of alkoxy-substituted difluorobenzene and alkyl-substituted difluorobenzene based on quinoxaline (Qx) as the electron acceptor unit and benzodithiophene as the electron donor unit, named HFQx-T and HFAQx-T, were used as electron donor polymers to fabricate all-polymer solar cells (all-PSCs) with a naphthalenediimide-bithiophene n-type semiconducting polymer (N2200). Usually, halogenated solvents are harmful to natural environment and human beings, and solvent additives were disadvantageous in the process of roll-to-roll technology. The Qx-based polymers are successfully used to fabricate high-performance all-PSCs, which processed with the nonhalogenated solvent tetrahydrofuran (THF) at room temperature.

Parylene C as a versatile dielectric material for organic field-effect transistors.

An emerging new technology, organic electronics, is approaching the stage of large-scale industrial application. This is due to a remarkable progress in synthesis of a variety of organic semiconductors, allowing one to design and to fabricate, so far on a laboratory scale, different organic electronic devices of satisfactory performance. However, a complete technology requires upgrading of fabrication procedures of all elements of electronic devices and circuits, which not only comprise active layers, but also electrodes, dielectrics, insulators, substrates and protecting/encapsulating coatings.

Balanced Ambipolar Organic Field-Effect Transistors by Polymer Preaggregation.

Ambipolar organic field-effect transistors (OFETs) based on heterojunction active films still suffer from an imbalance in the transport of electrons and holes. This problem is related to an uncontrolled phase separation between the donor and acceptor organic semiconductors in the thin films. In this work, we have developed a concept to improve the phase separation in heterojunction transistors to enhance their ambipolar performance.

Microstructure-Dependent Charge Carrier Transport of Poly(3-hexylthiophene) Ultrathin Films with Different Thicknesses.

Since the interfacial order of conjugated polymers plays an essential role for the performance of field-effect transistors, comprehensive understanding on the charge carrier transport in ultrathin semiconducting films below thicknesses of 10 nm is required for the development of transparent and flexible organic electronics. In this study, ultrathin films based on poly(3-hexylthiophene) as conjugated polymer model system with a thickness range from single monolayer up to several multilayers are investigated in terms of microstructure evolution and electrical properties of different molecular weights. Interestingly, a characteristic leap in field-effect mobility is observed for films with thickness greater than four layers.

Evolution of high-temperature molecular relaxations in poly(2-(2-methoxyethoxy)ethyl methacrylate) upon network formation.

Copolymers of 2-(2-methoxyethoxy)ethyl methacrylate (poly(MEOMA)) are regarded as bioinert replacements of poly(-isopropylacrylamide) in some biomedical applications. Networks of poly(MEOMA) of various architecture form thermo-responsive hydrogels. Here, we present dielectric and mechanical spectroscopy studies on segmental motions and network relaxation processes in linear poly(MEOMA) and its networks - bare network and the network grafted with short poly(MEOMA) chains.

Poly(vinyl methyl ether) hydrogels at temperatures below the freezing point of water-molecular interactions and states of water.

Water interacting with a polymer reveals a number of properties very different to bulk water. These interactions lead to the redistribution of hydrogen bonds in water. It results in modification of thermodynamic properties of water and the molecular dynamics of water.

High-performance single crystal organic field-effect transistors based on two dithiophene-tetrathiafulvalene (DT-TTF) polymorphs.

Solution prepared single crystal organic field-effect transistors (OFETs) combine low-cost with high performance due to structural ordering of molecules. However, in organic crystals polymorphism is a known phenomenon, which can have a crucial influence on charge transport. Here, the performance of solution-prepared single crystal OFETs based on two different polymorphs of dithiophene-tetrathiafulvalene, which were investigated by confocal Raman spectroscopy and X-ray diffraction, are reported.

Raman resonance effect in liquid water.

Raman spectroscopy is a technique preferably used for studies of water structure because the proportions of intensities of main OH stretching modes are thought to reflect well a network of "intermonomer" hydrogen bonds as well as its disturbance by the presence of some solutes. The work presented herein demonstrates how the intensity ratio of two main components (around 3200 and 3400 cm (-1)) depends on the excitation wavelength in the visible range. Polarized Raman spectra indicate that the component at ca.

Harnessing ICl reduction processes for synthesis of different BEDT-TTF-based molecular conductors.

Both calculations and experimental data, showing the possibility of formation of I3-, I2Cl-, and ICl2- anions through ICl reduction processes, are described in detail. The above processes were used successfully for the preparation of different molecular conductors based on trihalide anions and bis(ethylenedithio)tetrathiafulvalene (BEDT-TTF). The reaction between ICl and BEDT-TTF occurring in a strong polar reaction media (epsilon > or = 34.