bluuebunny/crossref_metadata_2025_split huggingface dataset:
Cr/Cr Compound Bilayered Thin Film Black Matrix For Lcd Color Filter
Authors: Lee Byung Hak , Kim Lee Gon , Lee Si-Hyun 
Published: April 2011

AbstractThe effect of process parameters on the optical property of the chromium/chromium compound multilayered thin film black matrix for liquid crystal display color filter has been investigated. A chromium compound layer was deposited reactively by DC magnetron sputtering, using gas mixture of Ar, CO2, and N2 on soda-lime glass substrate. Metallic chromium layer deposition was followed to enhance the light obstruction of the black matrix. X-Ray diffraction and transmission electron microscopy study showed that CrN is the major phase with unidentifiable oxides and carbides present as minor phases, in chromium compound layer, with nanocrystalline structure. Metallic chromium layer showed columnar growth structure. The ratio of CO2 in the reactive sputtering gas greatly affected the optical property of the multilayer, despite that N2 is the gas which contributes to the formation of the major phase. Delicate change of optical property is due to compositional variation of the compound layer, caused by reaction due to environmental changes. When processed with 10.28% of CO2 and 4.88% of N2 in 3.3 mTorr pressure, film with optical reflectivity of 3.31% at 655 nm of photon wavelength was obtained.
Improved Growth Of Srga2s4 Thin Film Electroluminescence Phosphors
Authors: Braunger D. , Oberacker T. A. , Troppenz U. , Schock H.-W. 
Published: April 2011

AbstractCerium activated ternary strontium thiogallate phosphor thin films have been deposited by multi-source evaporation of elemental strontium, gallium and sulfur as source materials. Cerium chloride (CeCI3) has been used as activator starting material. In order to avoid SrS as well as Ga phase segregations elemental In as well as compounds, such as LiF, NaF, LiCl, and SrCI2, have been investigated as possible growth enhancing agents.Coevaporation of indium resulted in an improved crystallization with the drawback of an increased reabsorption of the cerium emission. The other additives lead to improved crystal quality combined with true-blue cathodoluminescence (CL) performance (C.I.E. color coordinates of up to 0. 14/0.12) which proves phosphor layers without any SrS phase segregations.Thin film electroluminescent (TFEL) devices with SrGa2S4:CeCl3 phosphor layers prepared with LiF as additive exhibit highest ever reported L40 luminances of 78 cd/m2 and luminous efficiencies of 0.017 lm/W at a transferred charge of 1 μ;C/cm2 with 1 kHz / 50 μs bipolar square wave excitation.
Electron Injection Effects in Electroluminescent Devices Using Polymer Blend Thin Films
Authors: Wu C. C. , Sturm J. C. , Register R. A. , Suponeva L. , Thompson M. E. 
Published: April 2011

AbstractIn this paper, we discuss the effects of electron injection on electroluminescence (EL) efficiency in single-layer EL devices using blends of poly(N-vinylcarbazole) (PVK) and poly(3-nbutyl- p-pyridyl vinylene) (Bu-PPyV). Pure Bu-PPyV thin films suffer from formation of excimers due to the strong interchain interaction. Diluting Bu-PPyV with the high-energy-gap and holetransporting polymer PVK suppresses excimer formation and substantially raises both photoluminescence (PL) and EL efficiencies. The emission color is converted from red to green, indicating a transition from excimer emission to monomer emission of Bu-PPyV. The electron injection and EL efficiency can be fluther improved by adding small-molecule oxadiazoles into the blends as electron-transport materials. In optimized devices, an external EL quantum efficiency (backside emission only) as high as 0.8% photon/electron and practical brightnesses of 100 cd/m2 and 1000 cd/m2 can be achieved at ∼9V and ∼13.5V, respectively.
Poly(bithiazole)s: A New Class of Conjugated Polymers for Polymer-Based Light-Emitting Diodes
Authors: Politis J. K. , Nanos J. , He Yi , Kanicki J. , Curtis M. D. 
Published: April 2011

AbstractA new class of conjugated polymers have been synthesized based on the bithiazole moiety. The photoluminescence (PL) of these polymers ranges throughout the visible, from blue-green to red. These materials also show high stability, both thermal and oxidative. Therefore, it appears that this class of polymers are good candidates for polymer-based light emitting diodes.
Optical Studies of Znse Nanocrystals In Potassium Borosilicate Glass Matrices
Authors: Smith Christine A. , Risbud Subhash H. , Lee Howard W. H. , Cooke J. Diane 
Published: April 2011

AbstractWe have prepared ZnSe nanocrystals embedded in potassium borosilicate glass matrices in concentrations up to 14 wt%. The optical and electronic properties of these nanocrystals as a function of the fabrication process were investigated with High Resolution Transmission Electron Microscopy (HRTEM) and various optical techniques including absorption, photoluminescence, and excitation spectroscopy, and photoluminescence lifetime measurements. HRTEM confirms the presence of nanocrystals and indicates an average diameter size of 50 Å. The majority of the photoluminescence extends throughout the visible and is highly red-shifted from the absorptionedge, indicating emission from trap states such as Se vacancies. Contributions from the ZnSe nanocrystals as well as the borosilicate glass matrix are also observed. Exponential and biexponential photoluminescence decays are observed with decay times ranging from a few nanoseconds to a few hundred nanoseconds. The significance of these results to the optical and electronic properties of the ZnSe nanocrystals and their relevance as luminescent materials for light emitting applications will be discussed.
The True Liquid Crystal Approach to Mesoporous Silica
Authors: Attard George S. , Edgar Mark , Emsley James W. , Göltner Christine G. 
Published: April 2011

AbstractLiquid crystalline phases, consisting of nonionic surfactant and water, are exploited as templates for the synthesis of inorganic nanostructures In this approach the aqueous domains of a lyotropic liquid crystal phase function as a confining medium, in which the polymerisation of a watersoluble precursor takes place without destroying the nanostructure. Conducting the prepration of mesoporous silica in a lyotropic liquid crystal phase has considerable advantages over previous routes towards mesoporous ceramic oxides. (i) The nanostructure of the solid can be predicted a priori by knowing the phase structure of the liquid crystal before solidification, (ii) this approach allows the use of nonionic surfactants as templates, (iii) the progress of the reaction can be observed by a variety of methods, such as polarised light optical microscopy, X-ray diffraction, and deuterium NMR spectroscopy, all of which are noninvasive. The synthesis and a new way of monitoring the temporal evolution of the inorganic nanostructure using deuterium NMR spectroscopy are described. The results show unambiguously that the lyotropic liquid crystal phase acts as a template for the nanostructure.
Polymerization Effects on the Electro-Optic Properties of a Polymer Stabilized Ferroelectric Liquid Crystal
Authors: Guymon C. Allan , Dougan Lisa A. , Hoggan Erik N. , Bowman Christopher N. 
Published: April 2011

AbstractThe introduction of polymeric materials into liquid crystal (LC) matrices has been the focus of much interest in recent years. When a small percentage of polymer network is introduced, the mechanical strength of an LC system increases dramatically without significantly altering the electro-optic properties of the LC. One particular group of LCs, namely, ferroelectric liquid crystals (FLCs), are excellent candidates for such stabilization. FLCs, despite showing great potential for use in electro-optic and display technology due to inherently fast switching times and bistability, have found limited use as they are extremely susceptible to mechanical shock. This study examines the effects of polymerization conditions of a diacrylate monomer in an FLC on its inherent electro-optic properties. The LC phase in which polymerization occurs has a dramatic effect on the polymerization behavior and formation of the polymer network. Such effects have interesting implications on the ferroelectric polarization and switching speed of the FLC. As the temperature of polymerization increases and thus the order of the LC phase decreases, the ferroelectric polarization and the switching time increase.
Use of Glass-Forming Liquid Crystal Materials for Electroluminescent Diodes
Authors: Tsutsui T. , Lin C. P. , Saito S. , Chen S. H. , Shi H. , Mastrangelo J. C. 
Published: April 2011

AbstractSpin-coated thin films of cyclohexane-based liquid crystalline materials were used for the fabrication of electroluminescent diodes. Electroluminescence from single-component films of cyclohexane-based liquid crystalline materials was observed. Double component films composed of a cyclohexane-based liquid crystalline material and a conventional hole transport dye were shown to give improved electroluminescence performances, but emission was due to exciplexes composed of two components. Use of cyclohexane-based dye molecules was effective for suppressing the formation of inter-molecular complexes. The highest external quantum efficiency observed was 0.17%.
Phase-Separation Behavior and Electro-Optical Properties for (Polymer/Liquid Crystal) Composite Films
Authors: Kikuchi Hirotsugu , Jeong Hwan-Kyeong , Kajiyama Tisato 
Published: April 2011

AbstractDominant factors that control the aggregation structure and electro-optical properties were presented for (polymer/liquid crystal) composite films prepared by a solvent cast method from homogeneous solutions. Phase-separation behavior of the composite films consisting of a three dimensional polymer network and low molecular weight liquid crystals (LCs) embedded in the network was studied by evaluating the development of optical heterogeneity in the casting solution during film formation and by observing the morphology of the polymer networks. It was confirmed from light scattering studies of the casting solution during solvent evaporation that the phase-separated structure of polymer and LC was formed through spinodal decomposition. The resultant size of the LC domain in the composite film was controlled by regulating the solvent evaporation rate. The morphology of the polymer network in the composite film was also strongly influenced by the solubility between the polymer and the casting solvent. The electro-optical properties based on field controlled light scattering of the composite film were strongly dependent on the size of the LC domain. Though the rise response time decreased, the decay response time increased with an increase in the size of LC domains in the composite film. When poly(diisopropyl fumarate), which is not compatible with the LC, was used as the matrix polymer, no electro-optical hysteresis was observed, while considerable electro-optical hysteresis was observed for the composite film consisting of poly(methyl methacrylate), which shows a certain compatibility with the LC.
Studies of polymer ball type polymer dispersed liquid crystal films
Authors: Chang S. J. , Yin Y. C. , Lin C. M. , Fuh A. Y. G. 
Published: April 2011

AbstractPolymer dispersed liquid crystals ( PDLC ) are potentially useful as new types of display devices. By applying an electric field, one can switch the PDLC cell from a highly scattering opaque state to a transparent state. Normal PDLC cells consist of liquid crystal droplets, having sizes on the order of micrometers, embedded in a transparent polymer matrix. In this paper, we report the development of a new kind of PDLC cell with a distinct type of polymer morphology, teferred to as “reverse ” or “polymer ball ” type. The electro-optical behavior and the micro structure of the PDLC films were investigated by a He-Ne laser and the scanning electron microscopy ( SEA ) respectively.
Advances in Liquid Crystals for Am-Lcd
Authors: Kenji Furukawa , Etsuo Nakagawa , Yasuyuki Goto 
Published: April 2011

AbstractPhysical properties of mono-, di- and tri- fluorobenzenc derivatives with different core structures consisting of 3-ring system were measured. By introduction of fluorine atoms, phase change telnperaturcs decreased, nematic temperature range narrowed, optical anisotropy and elastic constant decreased, and dielectric anisotropy increased. From a calculation with MOPAC ver. 6.0, it is clear that elastic constants depend upon shapes of molecules under a restricted condition.By blending the investigated compounds as main components, different nematic mixtures, having
low threshold voltage low viscosity, large optical anisotropy or wide nematic range, which are suitable for specific applications for AM-LCD, were obtained
Synthesis and Physical Properties of π -Conjugated Polymers Containing Mesogenic Group
Authors: Watanabe Y. , Koide N. 
Published: April 2011

AbstractNovel side chain type liquid crystalline polymers, polythiophene and poly(aryleneethynylene) [PAE], containing a mesogenic group in the side chain were synthesized. Polythiophene derivatives were obtained by dehalogenative polycondensation with zero-valence nickel complex under mild condition. PAE type polymers were obtained by coupling dihalo aromatic compound with diethynyl aromatic compound. Their thermal properties were examined by differential scanning calorimetry, optical microscopy and X-ray diffractometry. All polymers exhibited a smectic or nematic mesophase depending upon the polymer backbone and pendant mesogenic group. Polythiophene derivatives exhibited electrochemical activity. Annealing polythiophene derivatives led to a lower oxidation potential and a higher conductivity. The degree of the orientation of the polymer backbone was supported by polarized UV-vis measurement. An effective conjugated length became longer by introducing thiophene rings into the polymer backbone. A high quantum yield of fluorescence was observed for PAE type polymers.
Electronic Structures of P-Type Doped CuInS2
Authors: Yamamoto T. , Katayama-Yoshida H. 
Published: April 2011

AbstractWe have studied the electronic structures of CuIn(S0.875X0.125)2 (X=B, C, N, Si or P) based on the ab-initio electronic band structure calculations using the augmented spherical wave (ASW) method. We have clarified that the physical characteristics of the p-type doped CuInS2 crystals are mainly determined by a change in the strength of interactions between Cu and S atoms. On the basis of the calculated results, we discussed the material design considerations, such as controlling the strength of resistivity for p-type doped CulnS2 materials and converting the conduction type, from n-type to p-type by a codoping method.
Defect Distribution And Metastability in Chalcopyrite Semiconductors
Authors: Walter T. , Herberholz R. , Müller C. , Schock H. W. 
Published: April 2011

AbstractDeep levels in chalcopyrite based heterojunctions are investigated by capacitance techniques. A method is presented which allows the determination of defect distributions from admittance measurements. For CuInSe2 a defect level at 280 meV above the valence band with an attempt to escape frequency of about 1011 s-1 is detected. A characteristic defect structure consisting of a shallow defect level and a broad deep structure is observed for Cu(In, Ga)Se2. The depth of the shallow defect is affected by annealing treatments which are necessary to achieve the optimum performance of the devices. CulnS2grown under an excess of CuS exhibits a high density of shallow defects whereas for Cu-poor CuInS2 defects close to midgap position with a large capture cross section are observed. These defects are metastable with respect to current injection and illumination relaxing to the equilibrium state around room temperature. The increase of the defect density after illumination results in a reduced bucking current. CV measurements can be interpreted in terms of a high density of deep states.
Effect of CdCl2 Treatment of CdS Films on CdTe/CdS Solar Cells
Authors: Song W. , Mao D. , Feng L. , Zhu Y. , Aslan M. H. , Collins R. T. , Trefny J. U. 
Published: April 2011

AbstractWe investigated the effect of CdCl2 treatment of CdS films on the photovoltaic performance of polycrystalline CdTe/CdS solar cells. X-ray diffraction studies indicated that the diffusion of S into CdTe is qualitatively the same for CdTe/CdS films fabricated with both as-deposited and CdCl2-treated CdS. A major difference was observed in the extent of Te diffusion into CdS for the two types of CdS films. Full conversion of CdS into CdS1-yTey; was observed for films prepared with asdeposited CdS, while the formation of the ternary phase was below the detection limit for films prepared with CdCl2-treated CdS. Photoluminescence measurements confirmed this result. The difference in interdiffusion leads to differences in optical transmission of CdS films and spectral response of CdTe/CdS solar cells. An increase of 2.7 mA/cm2 in short-circuit current density was observed as a result of improved spectral response in the wavelength range of 500–600 nm for the CdCl2-treated CdS.
Comparison Between Al- and B-Doped Zno Window Layers For CuInSe2Thin Film Solar Cells
Authors: Nakada T. , Murakami N. , Kunioka A. 
Published: April 2011

AbstractA comparative study of several properties of ZnO:Al and ZnO:B films grown by magnetron sputtering has been performed. The influence of these window layers on device performance has also been investigated. Sputter-deposited ZnO:B films were used for the first time as a window material of CIS thin film solar cells. The short circuit current was improved by replacing ZnO:Al with ZnO:B window layers. A discussion of the issues relating to ZnO window layers for improving cell performance is presented.
Structure Effect on Electrical Properties of Ito Films Prepared by Rf Reactive Magnetron Sputtering
Authors: Meng Li-Jian , Santos M. P. dos 
Published: April 2011

AbstractITO films have been deposited onto glass substrates by rf reactive magnetron sputtering using In-Sn (90–10) alloy target. After the deposition, the films were annealed in air at 500 °C for 30, 60, 90 and 180 min respectively. The film structure varies as the annealing time is changed. The film electrical properties show a strongly dependence on the film structure. Although all the films show a preferred orientation along the (400) direction, the film which has high (222) diffraction peak intensity, has high carrier mobility and low resistivity.
Amorphous Silicon Films From Dichlorosilane and SiH4 For Solar Cells
Authors: Payne A. M. , Wagner S. 
Published: April 2011

AbstractWe have deposited amorphous silicon films from mixtures of dichlorosilane (SiH2CI2, DCS), and silane (SiH4) and made the first p-i-n solar cells using i-layers of this material. We measured optical and electronic transport properties of the DCS-derived films and relate them to the solar cell performance. The DCS cells are compared to standard cells made with SiH4.
Cost Impacts of Anti-Reflection Coatings on Silicon Solar Cells
Authors: Wong David C. , Waugh Art 
Published: April 2011

AbstractDespite the early discovery of the Photovoltaic effect by Bechquerel almost 107 years ago, its commercial value had never been seriously considered because of its high cost in production and low in energy conversion efficiency. A familiar predicament has restrained demand for photovoltaic application: People won't use them until they are affordable, but they won't get affordable until there is a mass market for them. As has happened in other expensive markets, businesses are desperate to crack the conundrum. Since the oil shortage in the 70s, crystalline solar cell efficiency has increased from 8% to over 13% to date on 100 mm2 commercial silicon cells by refining the process with advanced device technologies. Together with increased production volume, the cost per watt has been reduced from over $ 8 in the 80's to as low as $3 to day. However, the cost is still considered too high to compete with fossil fuel energy. Further cost reduction is necessary by improving the cell and module conversion efficiency. The increase in cell efficiency and the process to achieve the goal, however, have to follow the golden rule of economics that the operational cost is a fraction of the profit in return. It is shown numerically in this paper that Anti Reflection (AR) coating on silicon solar cells by Atmospheric Pressure Chemical Vapor Deposition (APCVD) technique for large volume production could have over 650% profit return.
More Insights Into the ZnO/a-SiC:H(B) Interface - An Improved TCO/p Contact
Authors: Böhmer E. , Siebke F. , Rech B. , Beneking C. , Wagner H. 
Published: April 2011

AbstractSolar cells based on amorphous silicon (a-Si:H) exhibit a decreased fill factor if ZnO is used as front electrode instead of SnO2. This is due to a poor electric contact between the ZnO and the p-type a-SiC:H(B) layer. To gain a deeper understanding of the chemical and electronic properties of the ZnO/p interface, in-situ XPS measurements were applied to thin a-SiC:H(B) films deposited on ZnO. The effects of CO2 and H2 plasma pretreatments on clean ZnO surfaces and the influence of deposition conditions on the ZnO/a-SiC:H interface were investigated. Upon H2 plasma treatment the formation of SiOx by chemical transport of Si from the reactor walls is observed. Furthermore, a shift of all core levels towards higher binding energies indicates the formation of an accumulation layer. CO2 plasma treatments show no effects on ZnO. Depth profiling across the ZnO/a-SiC:H interface indicates SiO2 formation on ZnO. The depth profile of ZnO related core levels exhibits two features: a reduction of the ZnO at the interface, and, after longer sputter times, a core level shift towards higher binding energy due to an hydrogen induced accumulation layer in the n-type ZnO. The latter causes a depletion of the p-layer resulting in an enhanced series resistance and diminished fill factor. To reduce the depletion layer thin highly conductive microcrystalline layers were introduced, increasing the fill factor up to 74%.
A Learning Curve Approach to Projecting Cost and Performance in Thin Film Photovoltaics
Authors: Cody George , Tiedje Thomas 
Published: April 2011

AbstractThe current cost of electricity generated by PV power is still extremely high with respect to utility power and there remain questions as to whether PV power can ever be competitive with electricity generated by fossil fuels. A previous paper by the authors supplied an objective framework for considering this important question and introduced analytical tools to define and project the technical/economic status of PV power through the year 2010. In this paper, we update this previous work in the context of the recent announcements by Amoco/Enron Solar of projected sales of PV power in 1997 at rates considerably less than the US average.
Optimization Of Porous Silicon Reflectance For Solar Cell Applications
Authors: Coles A. X. , Gerhardt R. A. , Rohatgi A. 
Published: April 2011

AbstractThe potential use of porous silicon as an antireflective coating on solar cells has recently been recognized. This study investigates the effect of current density, anodization time, and surface conditions on the reflectance of porous silicon which was fabricated by anodizing (100) float zone single crystal Si wafers. The wafers were coated on one side with Al prior to anodization, and a HFbased solution was used as the electrolyte. Current densities of 5 – 100 mA/cm2 were used to anodize both polished and unpolished wafers over time intervals ranging from 2sec - 30 minutes. Reflectance properties were tested over the 400 - 1100 nm range, and minimum reflectances of 3 – 5% were achieved. The reflectance of the best porous Si sample normalized with respect to the sun's spectrum compares favorably with the reflectance of a double layer ZnS/ MgF2 with prior texturing.