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Yasuhiko Shirota - One of the best experts on this subject based on the ideXlab platform.
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high performance organic photovoltaic devices using a new Amorphous molecular material with high hole drift mobility tris 4 5 phenylthiophen 2 yl phenyl amine
Advanced Functional Materials, 2009Co-Authors: Hiroshi Kageyama, Hitoshi Ohishi, Masatake Tanaka, Yutaka Ohmori, Yasuhiko ShirotaAbstract:A new Amorphous molecular material, tris[4-(5-phenylthiophen-2- yl)phenyl]amine (TPTPA), is synthesized and characterized. TPTPA forms a stable Amorphous Glass with a Glass-transition temperature of 83 °C when the melt sample is cooled. It also forms Amorphous thin films by a thermal deposition technique. TPTPA exhibits a hole drift mobility of 1.0 × 10 ―2 cm 2 V ―1 s ―1 at an electric field of 1.0 × 10 5 V cm ―1 and at 293 K, as determined by the time-of-flight method, which is of the highest level among those of Amorphous molecular materials. pn-Heterojunction organic photovoltaic devices (OPVs) using TPTPA as an electron donor and C 60 or C 70 as an electron acceptor exhibit high performance with fill factors of 0.66∼0.71 and power conversion efficiencies of 1.7∼2.2% under air-mass (AM) 1.5G illumination at an intensity of100mW cm ―2 , which are of the highest level ever reported for OPVs using Amorphous molecular materials.
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surface relief grating formation using a novel azobenzene based photochromic Amorphous molecular material tris 4 phenylazo phenyl amine
Molecular Crystals and Liquid Crystals, 2005Co-Authors: Toru Takahashi, Takahiro Tanino, Hiroyuki Ando, Hideyuki Nakano, Yasuhiko ShirotaAbstract:ABSTRACT A novel azobenzene-based photochromic Amorphous molecular material, tris[4-(phenylazo)phenyl]amine (TPAPA), was designed and synthesized. TPAPA was found to readily form an Amorphous Glass with a Glass-transition temperature of 67°C and to exhibit photochromism as Amorphous film. Irradiation of Amorphous film of TPAPA with two coherent Ar+ laser beams led to the formation of surface relief grating with a diffraction efficiency of 2 ≈ 3% and a modulation depth of ca. 100 nm.
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formation of a surface relief grating using a novel azobenzene based photochromic Amorphous molecular material
Advanced Materials, 2002Co-Authors: Hideyuki Nakano, Toru Takahashi, Toshiaki Kadota, Yasuhiko ShirotaAbstract:A new photochromic Amorphous molecular material based on an azobenzene, BFIAB, has been designed and synthesized. BFlAB readily forms an Amorphous Glass with a Glass-transition temperature of 97 °C and exhibits photochromism in the Amorphous solid film as well as in solution. The BFlAB Amorphous film forms a surface relief grating (see Figure) with a high diffraction efficiency and a large modulation depth by irradiation with two coherent 488 nm Ar + laser beams.
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multilayered organic electroluminescent device using a novel starburst molecule 4 4 4 tris 3 methylphenylphenylamino triphenylamine as a hole transport material
Applied Physics Letters, 1994Co-Authors: Yasuhiko Shirota, Yoshiyuki Kuwabara, Hiroshi Inada, Takeo Wakimoto, Hitoshi Nakada, Yoshinobu Yonemoto, Shin Kawami, Kunio ImaiAbstract:A novel π‐conjugated starburst molecule, 4,4’,4‘‐tris(3‐methylphenylphenylamino)triphenylamine (m‐MTDATA), which forms a stable Amorphous Glass, functions as an excellent hole transport material for organic electroluminescent devices. An electroluminescent device consisting of double hole transport layers of m‐MTDATA and 4,4’‐bis(3‐methylphenylphenylamino)biphenyl and an emitting layer of tris(8‐quinolinolato)aluminum exhibits a high luminance efficiency and significant durability.
H Erguig - One of the best experts on this subject based on the ideXlab platform.
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structural optical and electrical properties of ni doped cds thin films prepared by spray pyrolysis
Journal of Alloys and Compounds, 2013Co-Authors: A Rmili, A Louardi, F Ouachtari, A Bouaoud, B Elidrissi, T Chtouki, H ErguigAbstract:Abstract Un-doped and Ni-doped cadmium sulphide (Ni–CdS) thin films were prepared by spray pyrolysis technique using perfume atomizer, from aqueous solution of hydrated cadmium chloride (CdCl2⋅H2O) and thiourea (CS(NH2)2 as sources of cadmium and sulphur ions respectively. We used hexahydrated nickel chloride (NiCl2⋅6H2O) as the dopant. The films were deposited on heated Amorphous Glass substrates at 400 °C. The effect of the [Ni]/[Cd] ratio on the structural, morphological, optical and electrical properties of these films was investigated. X-ray diffraction (XRD) studies revealed that all the deposited films (un-doped and Ni-doped CdS) were polycrystalline with hexagonal structure and exhibited [1 0 1] preferential orientation. The scanning electron microscopy (SEM) images showed a dense surface structure composed of crystallites whose average size decreases when the [Ni]/[Cd] ratio increases. The optical study showed that all the films were highly transparent. The transmittance in the visible region varies between 70% and 85%, depending on the dopant concentration. The film obtained with the [Ni]/[Cd] ratio equal to 4 at.% Ni showed minimum resistivity of 1.3 × 105 Ω cm at room temperature.
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transparent conducting properties of ni doped zinc oxide thin films prepared by a facile spray pyrolysis technique using perfume atomizer
Materials Chemistry and Physics, 2013Co-Authors: A Bouaoud, A Louardi, A Rmili, F Ouachtari, B Elidrissi, T Chtouki, H ErguigAbstract:Abstract Undoped and Ni doped zinc oxide (Ni–ZnO) thin films were prepared by a facile spray pyrolysis technique using perfume atomizer from aqueous solution of anhydrous zinc acetate (Zn(CH3COOH)2 and hexahydrated nickel chloride (NiCl2·6H2O) as sources of zinc and nickel, respectively. The films were deposited onto the Amorphous Glass substrates kept at (450 °C). The effect of the [Ni]/[Zn] ratio on the structural, morphological, optical and electrical properties of Ni doped ZnO thin film was studied. It was found from X-ray diffraction (XRD) analysis that both the undoped and Ni doped ZnO films were crystallized in the hexagonal structure with a preferred orientation of the crystallites along the [002] direction perpendicular to the substrate. The scanning electron microscopy (SEM) images showed a relatively dense surface structure composed of crystallites in the spherical form whose average size decreases when the [Ni]/[Zn] ratio increases. The optical study showed that all the films were highly transparent. The optical transmittance in the visible region varied between 75 and 85%, depending on the dopant concentrations. The variation of the band gap versus the [Ni]/[Zn] ratio showed that the energy gap decreases from 2.95 to 2.72 eV as the [Ni]/[Zn] ratio increases from 0 to 0.02 and then increases to reach 3.22 eV for [Ni]/[Zn] = 0.04. The films obtained with the [Ni]/[Zn] ratio = 0.02 showed minimum resistivity of 2 × 10−3 Ω cm at room temperature.
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characterization of cobalt oxide thin films prepared by a facile spray pyrolysis technique using perfume atomizer
Journal of Alloys and Compounds, 2011Co-Authors: A Louardi, A Rmili, F Ouachtari, A Bouaoud, B Elidrissi, H ErguigAbstract:Abstract Cobalt oxide (Co 3 O 4 ) thin films were prepared by a facile spray pyrolysis technique using perfume atomizer from aqueous solution of hydrated cobalt chloride salt (CoCl 2 ·6H 2 O) as source of cobalt. The films were deposited onto the Amorphous Glass substrates kept at different temperatures (300–500 °C). The influences of molar concentration of the starting solution and substrate temperature on the structural, morphological and optical properties of (Co 3 O 4 ) thin films were studied. It was found from X-ray diffraction (XRD) analysis that the films prepared with molar concentration greater than 0.025 M/L were polycrystalline spinel type cubic structure. The preferred orientation of the crystallites of these films changes gradually from (6 2 2) to (1 1 1) when the substrate temperature increases. By Raman spectroscopy, five Raman active modes characteristic of Co 3 O 4 spinel type cubic structure were found and identified at 194, 484, 522, 620 and 691 cm −1 . The scanning electron microscopy (SEM) images showed micro porous structure with very fine grains less than 50 nm in diameter. These films exhibited also a transmittance value of about 70% in the visible and infra red range.
T.-a. Óvári - One of the best experts on this subject based on the ideXlab platform.
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intrinsic domain wall pinning in rapidly solidified Amorphous nanowires
Journal of Applied Physics, 2014Co-Authors: T.-a. Óvári, H. ChiriacAbstract:Magnetoelastic anisotropy calculations and experimental switching field data are used to investigate the origin of the domain wall pinning in rapidly solidified Amorphous Glass-coated nanowires and submicron wires. The correlation of experimental and calculated results have shown that the magneto-mechanical coupling between internal stresses induced during preparation and magnetostriction is responsible for the pinning of the domain walls in Amorphous wires with diameters below 300 nm, whilst in thicker submicron wires demagnetization is also important. The results are important for fully understanding and controlling magnetic switching in rapidly solidified Amorphous nanowires for future applications.
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Interdomain wall in Amorphous Glass-coated microwires
Physical Review B, 2007Co-Authors: Horia Chiriac, T.-a. Óvári, S. Corodeanu, G. AbabeiAbstract:Amorphous Glass-coated microwires display a core-shell-type magnetic structure, whose main components, the inner core and the outer shell, have been extensively studied. In this paper, the interdomain wall that separates these two main components of the core-shell structure is investigated. The wall position and width in microwires with various compositions and dimensions are calculated. Experimental investigation techniques, such as ferromagnetic resonance, ultrahigh frequency giant magnetoimpedance, and axial hysteresis loop measurements, are subsequently employed to investigate those regions of the microwires in which the presence of the interdomain wall is expected to have the most significant effects. The investigation of the interdomain wall unveils aspects of the magnetism of these materials and opens up the way for the development of methods of controlled optimization of their magnetic properties in order to improve their response as sensitive elements in magnetic sensor devices.
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optimized gmi response of co based Amorphous Glass coated microwires by direct control over the magnetoelastic anisotropy from the surface region
IEEE Transactions on Magnetics, 2007Co-Authors: H. Chiriac, M Tibu, S. Corodeanu, T.-a. ÓváriAbstract:Results on the correlation between microwire dimensions and anisotropy distribution in the surface region and subsequently on their influence on the magnitude of the GMI response are reported. Calculated results show a strongly nonlinear dependence of surface region anisotropy on the metallic core diameter. Theoretical results allow one to understand the complex relation between GMI response and microwire dimensions. A suitable criterion for the optimization of the magnitude of the GMI effect has been found. Glass thickness has little effect on the magnitude of the GMI effect in optimized microwires
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Size triggered change in the magnetization mechanism of nearly zero magnetostrictive Amorphous Glass-coated microwires
Journal of Applied Physics, 2007Co-Authors: Horia Chiriac, S. Corodeanu, M. Ţibu, T.-a. ÓváriAbstract:Results on the change in the magnetization mechanism with microwire dimensions in nearly zero magnetostrictive Co-based Amorphous Glass-coated microwires are reported. Microwires with a metallic core diameter of 20μm or more display a change in the magnetization mechanism from domain wall displacement to magnetization rotation with the increase of an externally applied tensile stress, which is equivalent to an increase of the Glass coating thickness. Microwires with the metallic core diameter below 20μm do not display this change in the magnetization mechanism. They are magnetized only through magnetization rotation. Experimental results are explained based on the competition between magnetostatic and magnetoelastic energy terms. Minimization of a preponderant magnetostatic term in the total free energy results in an axial easy axis of magnetization and a corresponding bistable magnetic behavior. Bistability vanishes if the magnetoelastic energy term becomes preponderant and the corresponding easy axis be...
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magnetic behavior of negative and nearly zero magnetostrictive Glass covered Amorphous wires
IEEE Transactions on Magnetics, 1996Co-Authors: H. Chiriac, T.-a. Óvári, Gh Pop, Firuta BarariuAbstract:Results on the magnetic behavior and properties of negative and nearly zero magnetostrictive Amorphous Glass-covered magnetic wires and on their changes determined by Glass removal, applied tensile stresses, and annealing are reported. The experimental data allow the explanation of their specific magnetic behavior as emerging from the changes produced in the domain structure by these factors. The similarity in behavior between negative and nearly zero magnetostrictive Glass-covered wires is due to the very high values of internal stresses induced during preparation.
H Garciamiquel - One of the best experts on this subject based on the ideXlab platform.
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dc and ac linear magnetic field sensor based on Glass coated Amorphous microwires with giant magnetoimpedance
Journal of Magnetism and Magnetic Materials, 2015Co-Authors: Victor M Garciachocano, H GarciamiquelAbstract:Abstract Giant Magnetoimpedance (GMI) effect has been studied in Amorphous Glass-coated microwires of composition (Fe 6 Co 94 ) 72.5 Si 12.5 B 15 . The impedance of a 1.5 cm length sample has been characterized by using constant AC currents in the range of 400 µA–4 mA at frequencies from 7 to 15 MHz and DC magnetic fields from − 900 to 900 A/m. Double peak responses have been obtained, showing GMI ratios up to 107%. A linear magnetic field sensor for DC and AC field has been designed, using two microwires connected in series with a magnetic bias of 400 A/m with opposite direction in each microwire in order to obtain a linear response from ±70 (A/m) rms for AC magnetic field, and ±100 A/m for DC magnetic field. A closed loop feedback circuit has been implemented to extend the linear range to ±1 kA/m for DC magnetic field.
Tobin J Marks - One of the best experts on this subject based on the ideXlab platform.
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cdo as the archetypical transparent conducting oxide systematics of dopant ionic radius and electronic structure effects on charge transport and band structure
Journal of the American Chemical Society, 2005Co-Authors: Yu Yang, Andrew W Metz, Arthur J Freeman, Shu Jin, Julia E Medvedeva, John R Ireland, Mark C Hersam, Tobin J MarksAbstract:A series of yttrium-doped CdO (CYO) thin films have been grown on both Amorphous Glass and single-crystal MgO(100) substrates at 410 degrees C by metal-organic chemical vapor deposition (MOCVD), and their phase structure, microstructure, electrical, and optical properties have been investigated. XRD data reveal that all as-deposited CYO thin films are phase-pure and polycrystalline, with features assignable to a cubic CdO-type crystal structure. Epitaxial films grown on single-crystal MgO(100) exhibit biaxial, highly textured microstructures. These as-deposited CYO thin films exhibit excellent optical transparency, with an average transmittance of >80% in the visible range. Y doping widens the optical band gap from 2.86 to 3.27 eV via a Burstein-Moss shift. Room temperature thin film conductivities of 8,540 and 17,800 S/cm on Glass and MgO(100), respectively, are obtained at an optimum Y doping level of 1.2-1.3%. Finally, electronic band structure calculations are carried out to systematically compare the structural, electronic, and optical properties of the In-, Sc-, and Y-doped CdO systems. Both experimental and theoretical results reveal that dopant ionic radius and electronic structure have a significant influence on the CdO-based TCO crystal and band structure: (1) lattice parameters contract as a function of dopant ionic radii in the order Y (1.09 A) Y > Sc; (3) the dopant d state has substantial influence on the position and width of the s-based conduction band, which ultimately determines the intrinsic charge transport characteristics.
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cdo as the archetypical transparent conducting oxide systematics of dopant ionic radius and electronic structure effects on charge transport and band structure
Journal of the American Chemical Society, 2005Co-Authors: Yu Yang, Andrew W Metz, Arthur J Freeman, Julia E Medvedeva, John R Ireland, Mark C Hersam, Jun Ni, Tobin J MarksAbstract:A series of yttrium-doped CdO (CYO) thin films have been grown on both Amorphous Glass and single-crystal MgO(100) substrates at 410 °C by metal−organic chemical vapor deposition (MOCVD), and their phase structure, microstructure, electrical, and optical properties have been investigated. XRD data reveal that all as-deposited CYO thin films are phase-pure and polycrystalline, with features assignable to a cubic CdO-type crystal structure. Epitaxial films grown on single-crystal MgO(100) exhibit biaxial, highly textured microstructures. These as-deposited CYO thin films exhibit excellent optical transparency, with an average transmittance of >80% in the visible range. Y doping widens the optical band gap from 2.86 to 3.27 eV via a Burstein−Moss shift. Room temperature thin film conductivities of 8540 and 17 800 S/cm on Glass and MgO(100), respectively, are obtained at an optimum Y doping level of 1.2−1.3%. Finally, electronic band structure calculations are carried out to systematically compare the structu...