Search

Research was conducted to examine the electroluminescence (EL) performance of organic light emitting diodes (OLEDs) with a thick doped hole transport layer (DHTL). The basic cell structure is an anode/DHTL/HTL/emitter layer/cathode. Results indicate that the combination of a hole transport polycarbonate polymer and a tris (4-bromophenyl) amiium hexachroloantimonate as a dopant can form thick DHTL with yield an excellent EL performance. The EL characteristics of doped OLEDs are presented.

The electroluminescent characteristics of single-layer organic light emitting diodes (SOLEDs) were examined using SOLED devices composed of an inert polymer in which emissive electron transport molecules, hole transport molecules and highly fluorescent dopants as luminescent centers are scattered. Two dopants, namely, rubrene and coumarin, were investigated. Results show that the two dopants differ in charge carrier recombination and emission mechanisms.

Second-harmonic generation in a uniaxial crystal in total-reflection geometry is precisely measured. A Y-cut plate and a Z-cut plate of quartz crystals were used as samples. The incident wave is totally reflected by a glass prism in contact with the sample crystal, and an evanescent wave penetrates into the sample as a fundamental wave. The results gave the quantitative values of the components for a nonlinear optical susceptibility tensor with various polarizations and with Y-cut and Z-cut quartz plates. This technique can be applied to various samples to evaluate their nonlinear optical efficiencies.

We investigate the effects of volatile additives in solutions used to prepare thin-film transistors (TFTs) of regioregular poly(3-hexylthiophene) (P3HT). We use the additives trifluoromethylbenzene (TFMB) and methylcyclohexane (MCH) because they are poor solvents for P3HT. The additives improve the performance of the resulting TFTs when the boiling point (Tb) of the major solvent, carbon tetrachloride, is lower than that of the additive. The maximum mobility is (4.0 ± 0.9) × 10-2 cm2V-1s-1, which is 6.1 times larger than that of TFTs prepared without TFMB or MCH added to the solution; the on/off ratio and the subthreshold slope were also improved. The relative Tb of the solvent and the additive affected the film formation with the amount of TFMB or MCH remaining at the final stage of thin film deposition influencing the precipitation of P3HT aggregates. [ABSTRACT FROM AUTHOR]

The authors report that thermal treatment effect on various N,N′-dialkyl-3,4,9,10-perylene tetracarbxylic diimides [PTCDI-Cn, alkyl-dodecyl (n=12), butadecyl (n=14), octadecyl (n=18)] thin-film transistors (TFTs) depends on the substituted alkyl chain length. It is clearly demonstrated that there are two kinds of molecular movements during the thermal treatment on PTCDI films; molecular rearrangement in the same layer and molecular migration from the lower layer to the upper layer. The former is directly related to the grain growth and can be controllable by applying an external electric field. The latter is also related not only to the grain growth but also to the formation of cracks between grains. These two movements show opposite dependence on the alkyl chain length during the thermal treatment; the former is more active in longer alkyl chain, but the latter in shorter one. However, they also have opposite effect to TFT performance, and PTCDI films with longer alkyl chains have great advantage on TFT performance for the thermal treatment. Consequently, PTCDI-C18 TFTs show the highest electron mobility as large as 1.2 cm2/V s after the thermal treatment at 140 °C. [ABSTRACT FROM AUTHOR]

To directly observe the behavior of single molecules in real time and space, the x-ray methodology, diffracted x-ray tracking, has been proposed. This system monitors the spots of a diffracted x ray from individual nanocrystals, which are labeled with the individual single molecules. To operate single molecular detection systems with x rays, it is necessary to fabricate dispersive nanocrystals and observe the diffracted spots from the nanocrystals. We succeeded in fabrications of dispersive one-dimensional (Mo/Si) nanocrystals with diameters of approximately 25 nm using reactive ion etching. Furthermore, we monitored well-defined diffracted x-ray spots from Mo/Si nanocrystals (2.5 bilayers: Mo/Si/Mo/Si/Mo, d-space = 5.0 nm) in real time (2.0 ms). [ABSTRACT FROM AUTHOR]

The various thermal treatment effects exhibited on the N-alkyl perylene diimide thin-film transistors (TFTs) with different alkyl chain are discussed. These effects are shown to be highly dependent on the substituted alkyl chain length.

A distributed feedback (DFB) resonator composed of gold (Au) nanoparticles is used to find a tunable lasing action of dye-doped glass films. Photoreduction of chloroauric ions doped in silica/titania (SiO2/TiO2) sol-gel films are used to fabricate the Au-DFB resonators having various periodic spacings of 400-600 nm.

The electroluminescence (EL) response of organic light-emitting diodes (OLEDS) with different metal cathodes and device-area dependence was investigated. Electron mobility in the bilayer showed mixed mobility features for each layer.

Reports on the effect of low energy helium[sup+] ion-beam bombardment upon the structure of pyrene thin films formed on quartz substrates. Measurement of film thickness on each sample in a region bombarded by ions and a region shadowed from ions; Effect of ion current density upon pyrene film structure; Chemical reaction induced by ion irradiation.

Provides information on a study concerning the fluorescence characterization of polymeric materials, methyl methacrylate films using excimer laser as an ablation source. Experiment; Effect of ablation on properties of polymer films; Fluorescence dynamics.

A study on the attraction of adult Propsilocerus akamusi midges to different-colored light traps was carried out from October 21 to November 15, 2013. The 6 colored lights used in light-emitting diode (LED) lamps were white, green, red, blue, amber, and ultraviolet (UV). The UV lamp attracted the most P. akamusi, followed by green, white, blue, amber, and red. A white pulsed LED light attracted only half the number of midges as did a continuous-emission white LED light. The result indicated that manipulation of light color, considering that the red LED light and/or pulsed LED light are not as attractive as the other colors, may be appropriate for the development of an overall integrated strategy to control nuisance P. akamusi in the Lake Suwa area. [ABSTRACT FROM AUTHOR]