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Vacuum Deposition (vacuum + deposition)
Selected AbstractsAn Alternative Approach to Constructing Solution Processable Multifunctional Materials: Their Structure, Properties, and Application in High-Performance Organic Light-Emitting DiodesADVANCED FUNCTIONAL MATERIALS, Issue 18 2010Shanghui Ye Abstract A new series of full hydrocarbons, namely 4,4,-(9,9,-(1,3-phenylene)bis(9H -fluorene-9,9-diyl))bis(N,N -diphenylaniline) (DTPAFB), N,N,-(4,4,-(9,9,-(1,3-phenylene)bis(9H -fluorene-9,9-diyl))bis(4,1-phenylene))bis(N -phenylnaphthalen-1-amine) (DNPAFB), 1,3-bis(9-(4-(9H -carbazol-9-yl)phenyl)-9H -fluoren-9-yl)benzene, and 1,3-bis(9-(4-(3,6-di- tert -butyl-9H -carbazol-9-yl)phenyl)-9H -fluoren-9-yl)benzene, featuring a highly twisted tetrahedral conformation, are designed and synthesized. Organic light-emitting diodes (OLEDs) comprising DNPAFB and DTPAFB as hole transporting layers and tris(quinolin-8-yloxy)aluminum as an emitter are made either by vacuum deposition or by solution processing, and show much higher maximum efficiencies than the commonly used N,N,-di(naphthalen-1-yl)- N,N,-diphenylbiphenyl-4,4,-diamine device (3.6 cd A,1) of 7.0 cd A,1 and 6.9 cd A,1, respectively. In addition, the solution processed blue phosphorescent OLEDs employing the synthesized materials as hosts and iridium (III) bis[(4,6-di-fluorophenyl)-pyridinato-N, C2] picolinate (FIrpic) phosphor as an emitter present exciting results. For example, the DTPAFB device exhibits a brightness of 47 902 cd m,2, a maximum luminescent efficiency of 24.3 cd A,1, and a power efficiency of 13.0 lm W,1. These results show that the devices are among the best solution processable blue phosphorescent OLEDs based on small molecules. Moreover, a new approach to constructing solution processable small molecules is proposed based on rigid and bulky fluorene and carbazole moieties combined in a highly twisted configuration, resulting in excellent solubility as well as chemical miscibility, without the need to introduce any solubilizing group such as an alkyl or alkoxy chain. [source] Rational Design of Charge-Neutral, Near-Infrared-Emitting Osmium(II) Complexes and OLED FabricationADVANCED FUNCTIONAL MATERIALS, Issue 16 2009Tsang-Chi Lee Abstract A new series of charge neutral Os(II) isoquinolyl triazolate complexes (1,4) with both trans and cis arrangement of phosphine donors are synthesized, and their structural, electrochemical and photophysical properties are established. In sharp contrast to the cis -arranged complexes 2,4, the trans derivative 1, which shows a planar arrangement of chromophoric N -substituted chelates, offers the most effective extended , -delocalization and hence the lowest excited state energy gap. These complexes exhibit phosphorescence with peak wavelengths ranging from 692,805,nm in degassed CH2Cl2 at room temperature. Near-infrared (NIR)-emitting electroluminescent devices employing 6,wt % of 1 (or 4) doped in Alq3 host material are successfully fabricated. The devices incorporating 1 as NIR phosphor exhibit fairly intense emission with a peak wavelength at 814,nm. Forward radiant emittance reaches as high as 65.02,µW,cm,2, and a peak EQE of ,1.5% with devices employing Alq3, TPBi and/or TAZ as electron-transporting/exciton-blocking layers. Upon switching to phosphor 4, the electroluminescence blue shifts to 718,nm, while the maximum EQE and radiance increase to 2.7% and 93.26 (,W,cm,2) respectively. Their performances are optimized upon using TAZ as the electron transporting and exciton-blocking material. The OLEDs characterized represent the only NIR-emitting devices fabricated using charge-neutral and volatile Os(II) phosphors via thermal vacuum deposition. [source] High Definition Digital Fabrication of Active Organic Devices by Molecular Jet Printing,ADVANCED FUNCTIONAL MATERIALS, Issue 15 2007J. Chen Abstract We introduce a high resolution molecular jet (MoJet) printing technique for vacuum deposition of evaporated thin films and apply it to fabrication of 30,,m pixelated (800,ppi) molecular organic light emitting devices (OLEDs) based on aluminum tris(8-hydroxyquinoline) (Alq3) and fabrication of narrow channel (15,,m) organic field effect transistors (OFETs) with pentacene channel and silver contacts. Patterned printing of both organic and metal films is demonstrated, with the operating properties of MoJet-printed OLEDs and OFETs shown to be comparable to the performance of devices fabricated by conventional evaporative deposition through a metal stencil. We show that the MoJet printing technique is reconfigurable for digital fabrication of arbitrary patterns with multiple material sets and high print accuracy (of better than 5,,m), and scalable to fabrication on large area substrates. Analogous to the concept of "drop-on-demand" in Inkjet printing technology, MoJet printing is a "flux-on-demand" process and we show it capable of fabricating multi-layer stacked film structures, as needed for engineered organic devices. [source] Direct Comparison of Highly Efficient Solution- and Vacuum-Processed Organic Solar Cells Based on Merocyanine DyesADVANCED MATERIALS, Issue 37 2010Nils M. Kronenberg Identically configured bulk heterojunction organic solar cells based on merocyanine dye donor and fullerene acceptor compounds (see figure) are manufactured either from solution or by vacuum deposition, to enable a direct comparison. Whereas the former approach is more suitable for screening purposes, the latter approach affords higher short-circuit current density and power conversion efficiency. [source] Flexible Fullerene Field-Effect Transistors Fabricated Through Solution ProcessingADVANCED MATERIALS, Issue 47 2009Chao-Feng Sung C60-based thin-film transistors are fabricated through solution processing. On rigid indium tin oxide glass, the transistors display electron mobilities as high as 0.21,cm2 V,1 s,1 and a threshold voltage of 0.7,V, only slightly lower than those of organic thin-film transistors prepared through vacuum deposition. On ITO-coated PET substrates, the mobilities in the flexible devices (see image) are approximately one order of magnitude lower than those of devices prepared on rigid glass substrates. [source] Formation of Europium Chelate Complexes by Vacuum Co-Deposition and Their Application in Organic Light-Emitting Diodes,ADVANCED MATERIALS, Issue 13 2004T. Oyamada A unique method of material synthesis based on vacuum co-deposition is reported. A Eu complex was formed by co-deposition of bis(dipivaloymethanato)europium (Eu(DPM)3) and 2,9-dimethyl-4,7-diphenyl-1,10-phenanthroline (BCP), which both showed excellent volatility during vacuum deposition. Photoexcitation of the BCP led to intense emission from the Eu3+ ions, verifying efficient exciton energy transfer and therefore complex formation. [source] Studies on structural and optical properties of Cu-Sb-O thin filmsPHYSICA STATUS SOLIDI (C) - CURRENT TOPICS IN SOLID STATE PHYSICS, Issue 9 2010Nadia Chaglabou Abstract We report in this paper the structural and optical properties of Cu-Sb-O thin films systems. Samples were prepared via sequential thermal vacuum deposition of Cu and Sb or Sb and Cu (10 -5 Torr) on glass substrates after what they were heated in vacuum at 200 °C for 1 hour. So, the obtained intermetallic multilayer systems (Cu/Sb)j=1,2,3 and (Sb/Cu)j=1,2,3 were annealed in air atmosphere between 30°C and 400 °C for 3 h for j=1; for 6 h for j=2 and for 9 h for j=3. These films were characterized for their structural, surface morphological, compositional, and optical properties by using X-ray diffraction (XRD) and optical (transmittance and reflectance) measurement techniques. The X-ray diffraction (XRD) patterns revealed the presence of CuO, Sb2O3 and Sb2O4phases. The absorption coefficient of Cu-Sb-O thin films in all cases is in the range104 -105 cm -1. The films after annealing have two direct band gap energies in the ranges 1.48,1.50 eV and 2.20-2.95 eV. The electrical measurements show a conversion from a metallic phase to the semiconductor phase after annealing. The samples exhibit p-type conductivity after annealing in air of the intermetallic multilayer systems (Cu/Sb)j=3 and (Sb/Cu)j=3. (© 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Fabrication of 2-D nanostructures via metal deposition through a colloidal mask: comparison between thermal evaporation and RF magnetron sputteringPHYSICA STATUS SOLIDI (C) - CURRENT TOPICS IN SOLID STATE PHYSICS, Issue 12 2008Magdalena Ulmeanu Abstract We use spherical polystyrene beads in the size range from 500 nm - 2 ,m to form lithographic masks on surfaces. The masks consist of hexagonally arranged monolayers of these particles formed independently via a self-organized process upon solvent evaporation. With the help of the so called floating technique, the masks can be transferred to almost any arbitrary substrate. They have been utilized e.g. as masks for vacuum deposition, ion etching, or as masters for micro-contact-printing. Current research concentrates on the structure differences when the film deposition was done by thermal evaporation or RF magnetron sputtering. Investigations have been done on different metallic films, with emphasizes on Au thin film. The structures were investigated by atomic force microscopy (AFM) and scanning force microscopy (SEM). The differences in the nanostructures obtained after the removal of the colloidal mask will be evaluated in respect with the thin film deposition technique. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] High throughput testing platform for organic Solar CellsPROGRESS IN PHOTOVOLTAICS: RESEARCH & APPLICATIONS, Issue 7 2008Moritz K. Riede Abstract In this paper we present a high throughput testing setup for organic solar cells that is necessary for an efficient analysis of their behaviour. The setup comprises process parameter logging, automated measurement data acquisition and subsequent data management and analysis. Utilising this setup the reproducibility of solar cells and the effect of production parameter variations has been tested with a set of 360 solar cells based on the poly-3-hexylthiophene:1-(3-methoxycarbonyl)-propyl-1-1-phenyl-(6,6)C61 bulk heterojunction. Variations in power conversion efficiency between 1 and 3% were observed on varying production parameters hardly mentioned in literature. The conditions during the vacuum deposition of the aluminium cathode turned out to have a significant effect. The key solar cell parameter affecting the performance was the fill factor (FF). As such the work exemplifies the necessity for a combined approach to analyse the complex behaviour of organic solar cells. The developed high throughput testing setup provides a basis for an efficient testing of production parameter variations and materials and additionally opens the door for statistical analysis. Copyright © 2008 John Wiley & Sons, Ltd. [source] Synthesis of Oligo(thienylfuran)s with Thiophene Rings at Both Ends and Their Structural, Electronic, and Field-Effect PropertiesCHEMISTRY - AN ASIAN JOURNAL, Issue 12 2007Yasuo Miyata Dr. Abstract Oligo(thienylfuran)s with thiophene rings at both ends (SOSOSOS, DE-SOSOS, DH-SOSOS, DE-SOSOSOS, and DH-SOSOSOS; S and O denote thiophene and furan rings, respectively, DE and DH denote diethyl- and dihexyl-substituted, respectively) were newly synthesized by repetitive Stille coupling reactions. The UV/Vis maximum absorptions of the oligomers, SO, SOSO, SOSOS, SOSOSO, and SOSOSOS, exhibited a clear bathochromic shift with increasing number of heterocycles. The value of the oxidation peak potential (Epa1) determined by cyclic voltammetry decreased with an increase in the number of heterocycles by 0.06,0.08,V per heterocycle. The crystal-packing structures of DE-SOSOS and DH-SOSOS determined by X-ray crystallography have a herringbone motif and are denser than the reported structures of pentacene and ,-sexithiophene. The morphologies of thin films prepared by vacuum deposition and spin coating were investigated by atomic force microscopy and X-ray diffraction. Among these films, those of DE-SOSOS and DH-SOSOS exhibited highly ordered arrangements. The devices based on vacuum-deposited and spin-coated films of DE-SOSOS and DH-SOSOS displayed the highest FET mobilities of 10,2,10,3,cm2,V,1,s,1 among the oligomers reported in this study. [source] | ||||||||||