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Injection Layer (injection + layer)

Distribution by Scientific Domains

Polymers and Materials Science	85%

Selected Abstracts

Enhanced Performance of Fullerene n-Channel Field-Effect Transistors with Titanium Sub-Oxide Injection Layer

ADVANCED FUNCTIONAL MATERIALS, Issue 9 2009
Shinuk Cho
Abstract Enhanced performance of n-channel organic field-effect transistors (OFETs) is demonstrated by introducing a titanium sub-oxide (TiOx) injection layer. The n-channel OFETs utilize [6,6]-phenyl-C61 butyric acid methyl ester (PC61BM) or [6,6]-phenyl-C71 butyric acid methyl ester (PC71BM) as the semiconductor in the channel. With the TiOx injection layer, the electron mobilities of PC61BM and PC71BM FET using Al as source/drain electrodes are comparable to those obtained from OFETs using Ca as the source/drain electrodes. Direct measurement of contact resistance (Rc) shows significantly decreased Rc values for FETs with the TiOx layer. Ultraviolet photoelectron spectroscopy (UPS) studies demonstrate that the TiOx layer reduces the electron injection barrier because of the relatively strong interfacial dipole of TiOx. In addition to functioning as an electron injection layer that eliminates the contact resistance, the TiOx layer acts as a passivation layer that prevents penetration of O2 and H2O; devices with the TiOx injection layer exhibit a significant improvement in lifetime when exposed to air. [source]

Vertical-type organic device using thin-film ZnO transparent electrode

ELECTRICAL ENGINEERING IN JAPAN, Issue 2 2007
Hiroyuki Iechi
Abstract We propose a double heterojunction organic light-emitting diode (OLED) using a zinc oxide (ZnO) film, which works as a transparent and electron injection layer. The crystal structure of the ZnO films as a function of Ar/O2 flow ratio and the basic characteristics of the OLED depending on the ZnO sputtering conditions are investigated. Excellent characteristics of the novel OLED were obtained, as high as 470 cd/m2 at 22 V and 7.6 mA/cm2. The results obtained here demonstrate that the vertical organic light-emitting transistor (OLET) using a ZnO layer as an electron injection layer is promising as a key element for flexible sheet displays. © 2006 Wiley Periodicals, Inc. Electr Eng Jpn, 158(2): 49,55, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/eej.20151 [source]

Enhanced Performance of Fullerene n-Channel Field-Effect Transistors with Titanium Sub-Oxide Injection Layer

Highly Efficient Hole Injection Using Polymeric Anode Materials for Small-Molecule Organic Light-Emitting Diodes

ADVANCED FUNCTIONAL MATERIALS, Issue 3 2009
Kaushik Roy Choudhury
Abstract A novel, highly efficient hole injection material based on a conducting polymer polythienothiophene (PTT) doped with poly(perfluoroethylene-perfluoroethersulfonic acid) (PFFSA) in organic light-emitting diodes (OLEDs) is demonstrated. Both current,voltage and dark-injection-current transient data of hole-only devices demonstrate high hole-injection efficiency employing PTT:PFFSA polymers with different organic charge-transporting materials used in fluorescent and phosphorescent organic light-emitting diodes. It is further demonstrated that PTT:PFFSA polymer formulations applied as the hole injection layer (HIL) in OLEDs reduce operating voltages and increase brightness significantly. Hole injection from PTT:PFFSA is found to be much more efficient than from typical small molecule HILs such as copper phthalocyanine (CuPc) or polymer HILs such as polyethylene dioxythiophene: polystyrene sulfonate (PEDOT-PSS). OLED devices employing PTT:PFFSA polymer also demonstrate significantly longer lifetime and more stable operating voltages compared to devices using CuPc. [source]

Construction of Redispersible Polypyrrole Core,Shell Nanoparticles for Application in Polymer Electronics

ADVANCED MATERIALS, Issue 10-11 2009
Jianjun Wang
Redispersible conductive core,shell nanoparticles with a polystyrene core and a polystyrene sulfonate shell loaded with polypyrrole (PPy) are constructed. The smooth conducting thin films assembled from the PPy core,shell nanoparticles show high transmittance in the visible range and adequate adhesion to the substrates. Performance of light-emitting devices with the conducting thin film as the hole injection layer is tested and compared with the one based on PEDOT/PSS. [source]

Hole Injection in a Model Fluorene,Triarylamine Copolymer

ADVANCED FUNCTIONAL MATERIALS, Issue 2 2009
Hon Hang Fong
Abstract Recent developments in synthesis and purification have yielded conjugated polymers with hole mobilities exceeding 0.01,cm2 V,1 s,1. Essential to harvesting the potential of these materials in organic light emitting diodes (OLEDs) is the identification of suitable ohmic contacts. Using a model fluorene copolymer that shows high-mobility, non-dispersive hole transport, it is demonstrated that electrodes commonly used as anodes in OLEDs are very poor hole injectors. Injection from Au and indium tin oxide anodes is limited by energy barriers of 0.75 and 0.65,eV, respectively, and the injected current is found to be temperature independent,a prediction that was not reproduced by the leading injection model for disordered organic semiconductors. Injection from a poly(3,4-ethylenedioxythiophene) doped with poly(styrenesulfonate) (PEDOT:PSS) anode, on the other hand, is found to become less efficient with electric field, a behavior which is currently not understood. In thinner poly[(9,9,-dioctylfluorenyl-2,7-diyl)- co -(4,4,-(N -(4- sec -butyl))diphenylamine)] films, which are of relevance to OLEDs, ohmic losses on the PEDOT:PSS layer are found to limit the flow of current. These results illustrate the opportunity to further improve the performance of OLEDs as well as the challenge posed by high mobility conjugated polymers for the design of hole injection layers. [source]