Influence of gaseous annealing environment on the properties of indium-tin-oxide thin films

The influence of postannealing in different gaseous environments on the optical properties of indiu-tin-oxide (ITO) thin films deposited on glass substrates using e-beam evaporation has been systematically investigated. It is found that the annealing conditions affect the optical and electrical properties of the films. Atomic force microscopy, x-ray diffraction, and x-ray photoemission spectroscopy (XPS) were employed to obtain information on the chemical state and crystallization of the films. These data suggest that the chemical states and surface morphology of the ITO film are strongly influenced by the gaseous environment during the annealing process. The XPS data indicate that the observed variations in the optical transmittance can be explained by oxygen incorporation into the film, decomposition of the indium oxide phases, as well as the removal of metallic In. © 2005 American Institute of Physics.published_or_final_versio

Self-assembled monolayer formed by a rhenium complex containing hyperbranched polymer

The synthesis of a hyperbranched polymer containing a rhenium bipyridine complex is reported. The polymer was synthesized from a monomer that contains two chlorotricarbonyl rhenium(I) bipyridine moieties and a stilbazole ligand, and the polymer was formed by the coordination reaction in one single step. Gel permeation chromatography results showed that the resulting polymer had a strong interaction with the column packing material, which was reduced when the eluent was added with an electrolyte. Both atomic force microscopy and laser light scattering showed that the size of the polymer molecules was in the range between 25-30 nm. A monolayer of polymer molecules could form on a pretreated substrate by the self-assembly process, which can serve as the building block for multilayer ultrathin film devices.link_to_subscribed_fulltex

Gas-sensing properties of thick film based on ZnO nano-tetrapods

ZnO sensors were fabricated from ZnO tetrapod structures prepared in four different atmospheres and their gas-sensing properties were investigated. It was found that the gas-sensing properties were strongly dependent on the preparation atmosphere. This is likely due to the effects of the preparation atmosphere on the intrinsic defect concentration. It was found that the sensors based on tetrapods prepared in humidified Ar flow exhibited the best performance, characterized by high response, good selectivity and very short response time to dilute C 2H 5OH, making them promising candidates for practical detectors for dilute C 2H 5OH. © 2004 Elsevier B.V. All rights reserved.link_to_subscribed_fulltex

Perylene Tetracarboxylic Diimide (PTCDI) nanowires: Synthesis and characterization

Perylene tetracarboxylic diimide (PTCDI) is a material widely used in organic thin-film-based electronic and optoelectronic devices, such as transistors, light-emitting diodes and photovoltaic cells. It has been reported recently that copper phthalocyanine (CuPc) solar cell performance can be significantly improved if CuPc forms nanowires instead of flat film surface. However, nanostructures of PTCDI reported up to date include only self-assembled nanobelts in a solution, which is not suitable for small molecule device applications. For organic solar cells based on small molecules, vapor deposition organic nanostructure fabrication is of considerably more interest. In this work, fabrication of PTCDI nanostructures by evaporating PTCDI powder in Ar flow has been performed. The nanostructures were grown on glass, quartz and ITO (indium-tin oxide) substrates which were located downstream from the source. The obtained nanostructures were characterized by scanning electron microscopy (SEM) and photoluminescence (PL). The effect of substrate type, substrate temperature, gas flow rate and fabrication time on the resulting nanostructures were investigated. The synthesis conditions had significant effect on the morphologies of the resulting nanostructures, and the optimal fabrication conditions for device applications are discussed.link_to_subscribed_fulltex

Small molecule organic nanostructures-fabrication and properties

Organic materials are of great interest for the development of low cost electronic and optoelectronic devices. Although majority of research on organic materials is concerned with synthesis of novel compounds and organic thin films, organic nanostructures are attracting increasing interest in recent years. We briefly review different growth methods of organic nanostructures, which can be roughly divided into vapor deposition methods and self-assembly techniques in solution. Then we highlight some interesting properties of organic nanostructures, as well as possible applications, including field emission, electronic and optoelectronic devices.link_to_subscribed_fulltex

Spectroscopic ellipsometry of the optical functions of tris (8-hydroxyquinoline) aluminum (Alq3)

Optical functions of tris (8-hydroxyquinoline) aluminum (Alq3) have been studied in the spectral range from 1.55 to 5 eV using spectroscopic ellipsometry. The samples have been deposited by thermal evaporation on glass substrates. Optical functions of Alq3 deposited on unheated substrates and on substrates kept at 100 °C have been determined. The influence of atmosphere exposure to the optical properties of the Alq3 films has been investigated by photoluminescence measurements, absorption measurements, and spectroscopic ellipsometry. It has been found that the substrate temperature during evaporation affects the environmental stability of the films. © 2002 Elsevier Science B.V. All rights reserved.link_to_subscribed_fulltex

Stable White Light Electroluminescence from Highly Flexible Polymer/ZnO Nanorods Hybrid Heterojunction Grown at 50°C

<p>Abstract</p> <p>Stable intrinsic white light&#8211;emitting diodes were fabricated from c-axially oriented ZnO nanorods (NRs) grown at 50&#176;C via the chemical bath deposition on top of a multi-layered poly(9,9-dioctylfluorene-co&#8211;<it>N</it>-(4-butylpheneylamine)diphenylamine)/poly(9,9dioctyl-fluorene) deposited on PEDOT:PSS on highly flexible plastic substrate. The low growth temperature enables the use of a variety of flexible plastic substrates. The fabricated flexible white light&#8211;emitting diode (FWLED) demonstrated good electrical properties and a single broad white emission peak extending from 420 nm and up to 800 nm combining the blue light emission of the polyflourene (PFO) polymer layer with the deep level emission (DLEs) of ZnO NRs. The influence of the temperature variations on the FWLED white emissions characteristics was studied and the devices exhibited high operation stability. Our results are promising for the development of white lighting sources using existing lighting glass bulbs, tubes, and armature technologies.</p