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Artykuły w czasopismach na temat "Light emitting elements"
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Yulaeva, Yulia, Artem Khomyakov i Vasily Tuev. "A decomposition optical-mechanical model of a led emitting element". Science Bulletin of the Novosibirsk State Technical University, nr 4 (18.12.2020): 177–97. http://dx.doi.org/10.17212/1814-1196-2020-4-177-197.
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Light-emitting diodes are ahead of traditional light sources in terms of luminous efficacy (luminous flux per unit of electrical power consumption), which arouses an increased interest in the developers of LED lamps in the standard size of incandescent lamps. When designing LED lamps for direct replacement of incandescent lamps, it is necessary to ensure a spherical light distribution in these lighting devices. The design of the lamp with filamentary LED emitting elements is recognized as the best in terms of uniformity of the spatial distribution of light. In this work, a decomposition model of an LED emitting element has been developed, which is created on the basis of the parameters of an optical-mechanical model of LED emitting crystals, and includes the following sequentially performed actions: – construction of a geometric model of the LED emitting element; – determination of the properties of the surface source of the LED emitting element and the angular distribution of radiation of the LED emitting element model as a point emitter; – development of a primary model of an LED crystal with subsequent adjustment of its parameters; – verification of the decomposition model by comparison with the experimentally measured parameters of the LED emitting element. An assessment of the quality of the LED emitting element model as a point emitter was carried out; for this, the averaged measured and modeled LIDCs were superimposed at the same azimuthal angles on top of each other. The discrepancies between the calculated and experimental data do not exceed 10%, which confirms a high accuracy of the LED emitting element model as a point emitter. The resulting file is the properties of the surface source and the value of the luminous flux of the LED emitting element, equal to FW = 254 mW. The model is characterized by increased versatility and can be used for LED emitting elements with an arbitrary configuration of LED crystals and LED lamps based on them.
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Zhang, H. X., E. Gu, C. W. Jeon, Z. Gong, M. D. Dawson, M. A. A. Neil i P. M. W. French. "Microstripe-array InGaN light-emitting diodes with individually addressable elements". IEEE Photonics Technology Letters 18, nr 15 (sierpień 2006): 1681–83. http://dx.doi.org/10.1109/lpt.2006.879926.
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Kim, D. Y., D. Vak, J. Jo, J. Ghim, C. Chun, B. Lim i A. Heeger. "Polymers for Light-Emitting Devices with Integrated Hole-Transporting Elements". Synfacts 2006, nr 12 (grudzień 2006): 1236. http://dx.doi.org/10.1055/s-2006-955588.
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Hansen, Eric C., Yun Liu, Hendrik Utzat, Sophie N. Bertram, Jeffrey C. Grossman i Moungi G. Bawendi. "Blue Light Emitting Defective Nanocrystals Composed of Earth‐Abundant Elements". Angewandte Chemie International Edition 59, nr 2 (7.01.2020): 860–67. http://dx.doi.org/10.1002/anie.201911436.
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Hansen, Eric C., Yun Liu, Hendrik Utzat, Sophie N. Bertram, Jeffrey C. Grossman i Moungi G. Bawendi. "Blue Light Emitting Defective Nanocrystals Composed of Earth‐Abundant Elements". Angewandte Chemie 132, nr 2 (3.12.2019): 870–77. http://dx.doi.org/10.1002/ange.201911436.
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Bumai, Yurii, Aleh Vaskou i Valerii Kononenko. "Measurement and Analysis of Thermal Parameters and Efficiency of Laser Heterostructures and Light-Emitting Diodes". Metrology and Measurement Systems 17, nr 1 (1.01.2010): 39–45. http://dx.doi.org/10.2478/v10178-010-0004-x.
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Measurement and Analysis of Thermal Parameters and Efficiency of Laser Heterostructures and Light-Emitting DiodesA thermal resistance characterization of semiconductor quantum-well heterolasers in the AlGaInAs-AlGaAs system (λst≈ 0.8 μm), GaSb-based laser diodes (λst≈ 2 μm), and power GaN light-emitting diodes (visible spectral region) was performed. The characterization consists in investigations of transient electrical processes in the diode sources under heating by direct current. The time dependence of the heating temperature of the active region of a source ΔT(t), calculated from direct bias change, is analyzed using a thermalRTCTequivalent circuit (the Foster and Cauer models), whereRTis the thermal resistance andCTis the heat capacity of the source elements and external heat sink. By the developed method, thermal resistances of internal elements of the heterolasers and light-emitting diodes are determined. The dominant contribution of a die attach layer to the internal thermal resistance of both heterolaser sources and light-emitting diodes is observed. Based on the performed thermal characterization, the dependence of the optical power efficiency on current for the laser diodes is determined.
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Yu, Chao, Yifan Peng, Tianyi Guo, Qiang Fu, Haifeng Li i Xu Liu. "Beam shaping for multicolour light-emitting diodes with diffractive optical elements". Journal of Modern Optics 64, nr 4 (6.10.2016): 388–95. http://dx.doi.org/10.1080/09500340.2016.1240251.
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Caldiño, Ulises, Marco Bettinelli, Maurizio Ferrari, Elisa Pasquini, Stefano Pelli, Adolfo Speghini i Giancarlo C. Righini. "Rare Earth Doped Glasses for Displays and Light Generation". Advances in Science and Technology 90 (październik 2014): 174–78. http://dx.doi.org/10.4028/www.scientific.net/ast.90.174.
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Glasses are very versatile materials, also because of the ease of doping them with various elements and compounds. In particular, rare-earth-doped glasses have greatly contributed to the development of optical amplifiers, lasers, active optical waveguides and white-light-emitting devices. White light emitting diodes (W-LEDs) and color LEDS obtained by the combination of an UV emitting LED, such as AlGaN-based LED, with a glass phosphor exhibit very interesting properties. In the present contribution we report the luminescence characteristics of zinc-sodium-aluminosilicates glasses variously doped, namely either singly doped with Eu3+, Tb3+or Sm3+, or co-doped with Tb3+-Eu3+, Tb3+-Sm3+and Tb3+-Ce3+. These glasses have also proved to be suitable for ion exchange and therefore for the production of active optical waveguides.
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Parkova, Inese, Ivars Parkovs i Ausma Vilumsone. "Light-emitting textile display with floats for electronics covering". International Journal of Clothing Science and Technology 27, nr 1 (2.03.2015): 34–46. http://dx.doi.org/10.1108/ijcst-05-2013-0056.
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Purpose – Flexible light-emitting textile display is designed with floats for electronic elements covering and electronic contacts insulation what at the same time provides an opportunity to develop aesthetic design of the display in the single piece construction of material. The paper aims to discuss these issues. Design/methodology/approach – Display consists of interwoven electrically conductive yarns, non-conductive yarns and SMD LEDs connected to conductive yarns. Industrial jacquard weaving machine have been used, weave patterns were designed in PC-Edit software. Findings – Weave can be used as a tool to build and evolve electrotextile. Exploring weaving techniques and perceiving electronic circuit as a weave pattern, new approaches can be developed in electrotextile design field. Research limitations/implications – Connections of electronic elements and conductive textile materials still is actual problem what should be explored in further research. Practical implications – Flexible light emitting textile display can be used as output interface integrated into communication clothing by representing different animated images directly on clothing. Display also can be used for accessories, room and auto interior etc. applications. Originality/value – Paper describes method of light source integration directly into textile structure, combining functional and visual design of textile display.
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Kim, Hyeonbin, Jinho Keum i Moon Sung Kang. "NIR Light-Emitting Devices Based on Ligand-Crosslinked CuInS2/ZnS Quantum Dot Emissive Layer". Journal of Flexible and Printed Electronics 2, nr 1 (czerwiec 2023): 87–96. http://dx.doi.org/10.56767/jfpe.2023.2.1.87.
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Near-infrared (NIR) light-emitting components have gained attention for applications in sensing, communication, lighting, healthcare, and security. Colloidal CuInS2/ZnS quantum dots, composed of environmentally-friendly elements, are promising as active materials for NIR light-emitting devices. While the solution processibility of colloidal quantum dots allows for cost-effective film formation, it can also result in film dissolution when subsequent solution processes are performed to deposit upper functional layers during device fabrication. In this study, we demonstrate the effectiveness of ligand crosslinking in CuInS2/ZnS quantum dots, providing chemical tolerance to the film during subsequent solution processes. This enables the development of solution-based NIR light-emitting diodes, overcoming the film dissolution issue. Our findings open new possibilities for cost-effective fabrication of NIR devices using colloidal quantum dots.
Rozprawy doktorskie na temat "Light emitting elements"
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Siddiqui, Saiful Anam. "Erbium doped silicon light emitting diodes". Thesis, University of Surrey, 2003. http://epubs.surrey.ac.uk/843408/.
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Erbium, a rare earth element, has been shown to exhibit characteristic luminescence at 1.54mum due to its internal 4f transition from the first excited state (4pi3/2) to the ground state (4pi5/2). As this emission wavelength falls inside the maximum transmission window of silicon based optical fibers, erbium doped silicon might lead to the opportunity of silicon based optoelectronics. The introduction of erbium in silicon allows excitation through electron-hole recombination and subsequent radiative emission from the rare earth centers. The works reported here describe the structural, electrical and optical properties of crystalline silicon codoped with erbium and boron by ion implantation technique. Four sets of samples, co-implanted with erbium and boron at different Er dose, implantation energy and at different conditions, were prepared. Post-implantation annealing has been performed to recover the implantation damage to an acceptable value and to activate the dopant atoms optically and electrically. PL and EL measurements have been performed in the temperature range between 80K to room temperature. The sample with the lowest erbium concentration and energy gives the best PL and EL results. The observed emission peaks in both PL and EL measurements were at around 1.129mum, ~1.303mum, 1.50mum and 1.597mum at 80K. At higher temperatures, a broader peak at around 1.50mum with long tail towards the both end of wavelength has been observed. The peak at 1.129mum corresponding to the Si band edge emission, the reason for the peaks at around l.303mum has not been identified while the remaining two peaks correspond the Er3+ emission. Virtually no temperature quenching of Er luminescence is observed in some samples rather room temperature intensity is higher than that at 80K. The improvement of the temperature quenching effect on Er luminescence at room temperature has been attained in our results, which is significant improvement in comparison to the result found in the literature. The structural properties were studied by TEM in both cross-sectional and plan view configurations. TEM analyses showed dislocation loops and other defects of random size and distribution from the surface to 600nm below the surface. Er precipitates defects were also seen in the sample doped with Er comparatively at higher dose (1x1015Er/cm2) and energy (1.0 MeV). No detectable room temperature PL and EL signals were observed from the sample implanted at higher doses and energies.
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Habtemichael, Yishak Tekleab. "Packaging designs for ultraviolet light emitting diodes". Thesis, Georgia Institute of Technology, 2012. http://hdl.handle.net/1853/45764.
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Aluminum Gallium Nitride (AlGaN) / Gallium Nitride (GaN) based deep ultraviolet (DUV) light emitting didoes (LEDs) with emission wavelengths between 200-280 nm enable key emerging technologies such as water/air purification and sterilization, covert communications and portable bio-agent detection/identification systems for homeland security, and surface and medical device sterilization. These devices produce a large amount of undesired heat due to low quantum efficiencies in converting electrical input to optical output. These low efficiencies are attributed to difficulties in the growth&doping of AlₓGa₁₋ₓN materials and UV absorbing substrates leading to excessive joule heating, which leads to device degradation and a spectral shift in the emission wavelength. With this regard, effective thermal management in these devices depends on the removal of this heat and reduction of the junction temperature. This is achieved by decreasing the package thermal resistance from junction-to-air with cost-effective solutions. The use of heat sinks, thermal interface materials, and high conductivity heat spreaders is instrumental in the reduction of the overall junction-to-air thermal resistance.
This thesis work focuses on thermal modeling of flip-chip packaged deep UV LEDs to gain a better understanding of the heat propagation through these devices as well as the package parameters that have the biggest contributions to reducing the overall thermal resistance. A parametric study focusing on components of a lead frame package is presented to ascertain the thermal impacts of various package layers including contact metallizations, thermal spreading sub-mounts, and thermal interface materials. In addition the use of alternative thermal interface materials such as phase change materials and liquid metals is investigated experimentally.
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Yeo, Hyeonuk. "Synthesis of Optical Materials Based on Element-Blocks and Their Properties". 京都大学 (Kyoto University), 2017. http://hdl.handle.net/2433/225317.
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Williams, Jonathan H. T. "Finite element simulations of excitonic solar cells and organic light emitting diodes". Thesis, University of Bath, 2008. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.445404.
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Musolino, Mattia. "Growth, fabrication, and investigation of light-emitting diodes based on GaN nanowires". Doctoral thesis, Humboldt-Universität zu Berlin, Mathematisch-Naturwissenschaftliche Fakultät, 2016. http://dx.doi.org/10.18452/17409.
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Diese Arbeit gibt einen tiefgehenden Einblick in verschiedene Aspekte von auf (In,Ga)N/GaN Heterostrukturen basierenden Leuchtdioden (LEDs), mittels Molekularstrahlepitaxie entlang der Achse von Nanodrähten (NWs) auf Si Substraten gewachsen. Insbesondere wurden die Wachstumsparameter angepasst, um eine Koaleszierung der Nanodrähte zu vermindern. Auf diese Weise konnte die durch die NW-LEDs emittierte Intensität der Photolumineszenz (PL) um einen Faktor zehn erhöht werden. Die opto-elektronischen Eigenschaften von NW-LEDs konnten durch die Verwendung von Indiumzinoxid, anstatt von Ni/Au als Frontkontakt, verbessert werden. Zudem wurde demonstriert, dass auch selektives Wachstum (SAG) von GaN NWs auf AlN gepufferten Si Substraten mit einer guten Leistungsfähigkeit von Geräte vereinbar ist und somit als Wegbereiter für eine neue Generation von NW-LEDs auf Si dienen kann. Weiterhin war es möglich, strukturierte Felder von ultradünnen NWs durch SAG und thermische in situ Dekomposition herzustellen. In den durch die NW-LEDs emittierten Elektrolumineszenzspektren (EL) wurde eine Doppellinenstruktur beobachtet, die höchstwahrscheinlich von den kompressiven Verspannungen im benachbarten Quantentopf, durch die Elektronensperrschicht verursachten, herrührt. Die Analyse von temperaturabhängigen PL- und EL-Messungen zeigt, dass Ladungsträgerlokalisierungen nicht ausschlaggebend für die EL-Emission von NW-LEDs sind. Die Strom-Spannungs-Charakteristiken (I-V) von NW-LEDs unter Vorwärtsspannung wurden mittels eines Modells beschrieben, in das die vielkomponentige Natur der LEDs berücksichtigt wird. Die unter Rückwärtsspannung aktiven Transportmechanismen wurden anhand von Kapazitätstransientenmessungen und temperaturabhänigigen I-V-Messungen untersucht. Dann wurde ein physikalisches Modell zur quantitativen Beschreibung der besonderen I-V-T Charakteristik der untersuchten NW-LEDs entwickelt.This PhD thesis provides an in-depth insight on various crucial aspects of light-emitting diodes (LEDs) based on (In,Ga)N/GaN heterostructures grown along the axis of nanowires (NWs) by molecular beam epitaxy on Si substrates. In particular, the growth parameters are adjusted so as to suppress the coalescence of NWs; in this way the photoluminescence (PL) intensity emitted from the NW-LEDs can be increased by about ten times. The opto-electronic properties of the NW-LEDs can be further improved by exclusively employing indium tin oxide instead of Ni/Au as top contact. Furthermore, the compatibility of selective-area growth (SAG) of GaN NWs on AlN-buffered Si substrates with device operation is demonstrated, thus paving the way for a new generation of LEDs based on homogeneous NW ensembles on Si. Ordered arrays of ultrathin NWs are also successfully obtained by combining SAG and in situ post-growth thermal decomposition. A double-line structure is observed in the electroluminescence (EL) spectra emitted by the NW-LEDs; it is likely caused by compressive strain introduced by the (Al,Ga)N electron blocking layer in the neighbouring (In,Ga)N quantum well. An in-depth analysis of temperature dependent PL and EL measurements indicates that carrier localization phenomena do not dominate the EL emission properties of the NW-LEDs. The forward bias current-voltage (I-V) characteristics of different NW-LEDs are analysed by means of an original model that takes into account the multi-element nature of LEDs based on NW ensembles by assuming a linear dependence of the ideality factor on applied bias. The transport mechanisms in reverse bias regime are carefully studied by means of deep level transient spectroscopy (DLTS) and temperature dependent I-V measurements. The physical origin of the detected deep states is discussed. Then, a physical model able to describe quantitatively the peculiar I-V-T characteristics of NW-LEDs is developed.
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Eritt, Michael. "Großflächige Abscheidung organischer Leuchtdioden und Nutzung optischer Verfahren zur in situ Prozesskontrolle". Doctoral thesis, Universitätsbibliothek Chemnitz, 2011. http://nbn-resolving.de/urn:nbn:de:bsz:ch1-qucosa-63184.
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In der vorliegenden Arbeit wird die großflächige Abscheidung von organischen Leuchtdioden (OLED) für Beleuchtungsanwendungen in einer neuartigen Beschichtungsanlage vorgestellt. Ausgehend von den speziellen Anforderungen an gleichförmige Schichtdickenverteilung und hohe Abscheideraten für die organischen Schichten, sind die Verfahren der thermischen Vakuumverdampfung (VTE) und der organischen Dampfphasenabscheidung (OVPD) auf Substraten der Größe 370 x 470 mm² unter Fertigungsbedingungen kombiniert. Die Quellensysteme der Anlage wurden hinsichtlich der Verteilung des Materialauftrages und der Oberflächenrauigkeit qualifiziert. Die Kontrolle der Schichteigenschaften ist bei der organischen Dampfphasenabscheidung durch Variation der Parameter Substrattemperatur und Abscheiderate in einem weiten Bereich möglich. Die in situ Kontrolle der Schichtdicke mittels spektroskopischer Reflektometrie wird vorgestellt. Ein Messsystem ist in die Beschichtungsanlage integriert und abgeschiedene Schichten charakterisiert worden. Die Arbeit zeigt, dass die genaue Bestimmung der Dicke einzelner Schichten oder ganzer Schichtstapel mit diesem Verfahren möglich ist und zur ex situ Ellipsometrie vergleichbare Ergebnisse liefert. Um robuste OLED-Bauelemente herzustellen, wird eine organische Kurzschlussunterdrückungsschicht eingeführt, die konform mittels der OVPD-Technologie abgeschieden wird. Die strombegrenzenden Eigenschaften dieser Schicht wirken Defektströmen innerhalb der OLED entgegen. Die reproduzierbare Herstellung von 100 x 100 mm² großen, weißes Licht emittierenden OLED-Modulen mit mittleren Leistungseffizienzen von über 13 lm/W zeigt das Potential dieser TechnologieThe thesis deals with the large area deposition of organic light-emitting diodes (OLED) for lighting applications with a novel deposition tool. The special needs of film thicknesses homogeneity and high deposition rates for organic layers request the combination of thermal vacuum deposition (VTE) and organic vapour phase deposition (OVPD) processes to fabricate OLEDs on 370 x 470 mm² substrates. The deposition sources are qualified regarding layer homogeneity and morphology of the deposition processes. The layer properties are controlled in a wide range by the variation of the organic vapour phase deposition parameters: substrate temperature and deposition rate. The in situ determination of the substrate thickness is shown by the application of spectroscopic reflectometry. The thesis demonstrates the thickness analysis of single and multi-layer stacks by reflectometry. The data fit well to ex situ ellipsometry. Robust OLED devices with an additional short-circuit protection layer deposited by OVPD technology are introduced. The current limiting properties of this layer reduce the leakage currents in the OLED device. The fabrication of 100 x 100 mm² white emitting OLED modules with power efficiencies about 13 lm/W shows the great potential of the manufacturing technology
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Connors, Benjamin James. "Simulation of current crowding mitigation in GaN core-shell nanowire led designs". Thesis, Georgia Institute of Technology, 2011. http://hdl.handle.net/1853/41206.
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Core-shell nanowire LEDs are light emitting devices which, due to a high aspect
ratio, have low substrate sensitivity, allowing the possibility of low defect density GaN
light emitting diodes. Current growth techniques and physical non-idealities make the
production of high conductivity p-type GaN for the shell region of these devices difficult.
Due to the structure of core-shell nanowires and the difference in conductivity between ntype and p-type GaN, the full junction area of a core-shell nanowire is not used
efficiently. To address this problem, a series of possible doping profiles are applied to
the core of a simulated device to determine effects on current crowding and overall
device efficiency. With a simplified model it is shown that current crowding has a
possible dependence on the doping in the core in regions other than those directly in
contact with the shell. The device efficiency is found to be improved through the use of
non-constant doping profiles in the core region with particularly large efficiency
increases related to profiles which modify portions of the core not in contact with the
shell
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Bender, Vitor Cristiano. "Metodologia de projeto eletrotérmico de LEDs aplicada ao desenvolvimento de sistemas de iluminação pública". Universidade Federal de Santa Maria, 2012. http://repositorio.ufsm.br/handle/1/8510.
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Coordenação de Aperfeiçoamento de Pessoal de Nível SuperiorThis work presents an LED electrothermal design methodology applied to a street lighting system. The methodology aims to provide indicatives of the optimal LED operating point for lighting systems design, considering electrical, thermal and photometric system features. Different projects are developed according to the methodology, the theoretical results are compared with fluid dynamics simulation and demonstrated by experimental results. A research including luminous flux, luminous efficacy and flicker is performed considering the LED current ripple, defining acceptable levels of ripple based on the optimal operational point. The methodology is applied by developing a lighting system composed of an LED driver and a thermal dissipation system, comprising a luminaire, a heatsink and fans. The lighting system includes electrothermal feedback control. The results provide high power factor with low current harmonic distortion to the power grid. The LED operational temperature ensures the luminous flux maintenance over the system lifetime.
Este trabalho apresenta uma metodologia de projeto eletrotérmico de LEDs aplicada a um sistema de iluminação pública. A metodologia tem o objetivo de proporcionar indicativos do melhor ponto de operação do LED para o projeto de sistemas de iluminação, considerando os aspectos elétricos, térmicos e fotométricos envolvidos no sistema. Diferentes projetos são desenvolvidos utilizando a metodologia, os resultados teóricos obtidos são comparados com simulações computacionais de dinâmica dos fluidos e comprovados através de resultados experimentais. Um estudo do fluxo, eficácia e cintilação luminosa é também realizado considerando a ondulação de corrente aplicada aos LEDs, definindo os níveis aceitáveis de ondulação com base no ponto ótimo de operação. Para aplicação da metodologia é desenvolvido um sistema de iluminação pública composto por um circuito de acionamento dos LEDs e um sistema de dissipação térmica, formado por uma luminária, um dissipador de calor e ventiladores. O sistema de iluminação possui controle com realimentação eletrotérmica. Os resultados obtidos proporcionam alto fator de potência com baixa distorção harmônica ao sistema elétrico e temperatura de operação que garante a manutenção do fluxo luminoso dos LEDs durante toda a vida útil do sistema.
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Bender, Vitor Cristiano. "Modelagem e acionamento de diodos orgânicos emissores de luz (OLEDs) para sistemas de iluminação". Universidade Federal de Santa Maria, 2015. http://repositorio.ufsm.br/handle/1/3691.
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Coordenação de Aperfeiçoamento de Pessoal de Nível SuperiorThis thesis presents the study and characterization of organic light-emitting diodes (OLEDs) with the proposal of obtaining an equivalent model that is useful in the OLED driver design and in lighting systems projects. Initially, a literature review covering the operating principle and the constructive aspects of OLEDs is presented. From this, a model that integrates scale, photometrical, electrical and thermal aspects is proposed. This model is static and dynamic and is called EFET. A procedure for parameter identification of the model is proposed, jointly with an analysis of the intrinsic capacitance effect on the OLED electrical, thermal and photometrical performance. The proposed model is able to predict and simulate the OLED based lighting systems before building, saving time and cost. The model is validated using different OLED samples and conclusions are derived from the experimental validation and simulation results. An approach considering the dimming methods of OLEDs is presented, showing the chromatic impact caused by each method. Finally, an OLED driver based on the concept of switched capacitor converters is proposed. The thesis results are satisfactory and provide an enhancement to the state of the art in modeling and OLED driving.
A presente tese de doutorado apresenta o estudo e a caracterização de diodos orgânicos emissores de luz (OLEDs) com a proposta de um modelo equivalente que é útil no desenvolvimento de circuitos de acionamento e na análise de OLEDs, quando aplicados em sistemas de iluminação. Inicialmente, é apresentada uma revisão bibliográfica contemplando o princípio de funcionamento e os aspectos construtivos dos OLEDs. A partir disto, um modelo que integra os aspectos de escala, fotométricos, elétricos e térmicos é proposto. Esse modelo é denominado EFET e é dividido em estático e dinâmico. Uma proposta de procedimento para identificação dos parâmetros do modelo é apresentada, juntamente com a análise do efeito da capacitância intrínseca dos OLEDs no seu desempenho elétrico, térmico e fotométrico. Com o modelo proposto pode-se predizer e simular o comportamento dos OLEDs antes de construir o sistema de iluminação, reduzindo custos e tempo de desenvolvimento. O modelo é validado empregando diferentes amostras de OLEDs. Conclusões são obtidas a partir da validação experimental e de simulações empregando simuladores elétricos e da fluidodinâmica computacional através do método de elementos finitos. Uma abordagem considerando os métodos de ajuste da intensidade luminosa de OLEDs é apresentada, evidenciando o impacto cromático provocado por cada método. Por fim, um circuito de acionamento para OLEDs baseado no conceito de capacitores chaveados é proposto. Os resultados obtidos são satisfatórios e proporcionam um incremento ao estado da arte da modelagem e acionamento de OLEDs.
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Tu, Sheng-Han, i 杜昇翰. "Integration of special chip process and secondary elements for light emitting diodes illumination module". Thesis, 2010. http://ndltd.ncl.edu.tw/handle/82409340006152693592.
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博士國立中央大學
光電科學研究所
98
For the sake of energy shortage, the developments of new energy and energy saving have attracted the interests of advanced nations. The light emitting diodes possesses advantages such as low power consumption, compact volume and long life time so that it has took the place of conventional light source gradually. In this thesis we developed a series of methods that to crossed the chip process and lighting module enhance the light performance of light emitting diodes. We integrated special chip process and secondary optics element to form a lighting module that can be applied to different applications such as back light module of liquid crystal display, projector and street lamp. The adopted methods include imprinting technique, pad reflector, surface roughness, ThinGaN LED pattern design, the guided mode resonance (GMR) filter to enhance the output power efficiency of LED and modulate the lighting performances. The secondary optics elements were used to modulate the far-field pattern of LED to achieve an expanded or a collimator far-field pattern. In order to increase the light extraction efficiency and modulate the lighting performance of LED, we adopted the thermal stress free and room temperature imprinting technique. We imprinted the one and two dimension onto the chip surface by stable material SOG. After imprinting structure application, the output power enhancement reached 17% to 35%. Furthermore, the blazed grating can deflect the peak intensity of far-field pattern to 20° and the two dimensional structure can achieve an expansion far-field pattern. A GaN-based light-emitting diode (LED) with non-alloyed metal contacts and textured Ga-doped ZnO (GZO) contact layer were served as the n- and p-type electrode pads, respectively. Compared with the conventional LEDs with flat surface and Cr/Au metal contacts, the non-alloyed Ag/Cr/Au contacts used in the present experimental LEDs play the role of reflector to prevent the emitted light from absorption by the opaque electrode pads. Enhancement of light output power observed from the experimental LEDs is also due to the textured GZO layer that can disperse the angular distribution of photons at the GZO/air interface. With an injection current of 20mA, the enhancement of the LOP approximately has a 30% magnitude compared with conventional GaN-based LEDs. Finally, the numerical method was used to discussion the relation between output power and pad reflectivity. Several n-type electrode patterns were designed to evaluate the current spreading effects in high power ThinGaN light emitting diodes. A proposed three dimensional numerical simulation was used to investigate the current spreading distributions. The experimental current spreading tendencies in various n-type electrodes were consistent with the simulation results. The maximum lighting output power was enhanced to 11% in our electrode pattern designs. The current-voltage and luminance-current performance of LED chips can apparently be improved with a better current spreading distribution. Therefore, this three dimensional simulation method could be used for the advanced analysis and optimization of LED performance. A simple and hybrid combination of a green light-emitting diode (LED) chip with an asymmetric guided-mode resonance (GMR) filter is proposed to reduce the full-width-at-half-maximum (FWHM) of LED emission spectrum for the LED backlight system. The color gamut consisting of multiple LEDs is significantly expanded from 122 to 137. It also possesses stable transmittance within 5 degree incident angle for the unpolarized light. This GMR filter provides superior transmittance efficiency (84%), and FWHM performance (15nm). The fabrication tolerances of asymmetric GMR are also analyzed and discussed. A cost effective, high throughput, and high yield method for the increase of street lamp potency was proposed in this paper. We integrated the imprinting technology and the reflective optical element to obtain a street lamp with high illumination efficiency and without glare effect. The imprinting technique can increase the light extraction efficiency and modulate the intensity distribution in the chip level. The non-Lambertian light source was achieved by using imprinting technique. The compact reflective optical element was added to efficiently suppress the emitting light intensity with small emitting angle for the uniform of illumination intensity and excluded the light with high emitting angle for the prevention of glare. Compared to the convectional street lamp, the novel design has 40% enhancement in illumination intensity, the uniform illumination and the glare effect elimination.
Książki na temat "Light emitting elements"
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ZnO bao mo zhi bei ji qi guang, dian xing neng yan jiu. Shanghai Shi: Shanghai da xue chu ban she, 2010.
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Launay, Jean-Pierre, i Michel Verdaguer. Electrons in Molecules. Oxford University Press, 2018. http://dx.doi.org/10.1093/oso/9780198814597.001.0001.
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The book treats in a unified way electronic properties of molecules (magnetic, electrical, photophysical), culminating with the mastering of electrons, i.e. molecular electronics and spintronics and molecular machines. Chapter 1 recalls basic concepts. Chapter 2 describes the magnetic properties due to localized electrons. This includes phenomena such as spin cross-over, exchange interaction from dihydrogen to extended molecular magnetic systems, and magnetic anisotropy with single-molecule magnets. Chapter 3 is devoted to the electrical properties due to moving electrons. One considers first electron transfer in discrete molecular systems, in particular in mixed valence compounds. Then, extended molecular solids, in particular molecular conductors, are described by band theory. Special attention is paid to structural distortions (Peierls instability) and interelectronic repulsions in narrow-band systems. Chapter 4 treats photophysical properties, mainly electron transfer in the excited state and its applications to photodiodes, organic light emitting diodes, photovoltaic cells and water photolysis. Energy transfer is also treated. Photomagnetism (how a photonic excitation modifies magnetic properties) is introduced. Finally, Chapter 5 combines the previous knowledge for three advanced subjects: first molecular electronics in its hybrid form (molecules connected to electrodes acting as wires, diodes, memory elements, field-effect transistors) or in the quantum computation approach. Then, molecular spintronics, using, besides the charge, the spin of the electron. Finally the theme of molecular machines is presented, with the problem of the directionality control of their motion.
Części książek na temat "Light emitting elements"
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Nakamura, K., H. Ogura i T. Sugimoto. "Direct Visualization of High-Intensity Focused Ultrasonic Field Using Light-Emitting Diodes and Piezoelectric Elements". W Acoustical Imaging, 309–16. Dordrecht: Springer Netherlands, 2008. http://dx.doi.org/10.1007/978-1-4020-8823-0_43.
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Henrique Godoi, Bruno, Juliana Ferreira Strixino, Newton Soares da Silva i Cristina Pacheco Soares. "Can PDT Alter the Glycosylation of the Tumor Cell Membrane?" W Photodynamic Therapy - from Basic Science to Clinical Research [Working Title]. IntechOpen, 2020. http://dx.doi.org/10.5772/intechopen.94172.
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Photodynamic Therapy (PDT) is a cancer treatment that used the interaction of a photosensitizing drug and a light source. PDT can lead to changes in the expression of various cellular elements, compromising cell adhesion, and cytoskeleton integrity in cells undergoing treatment. However, the pathways of cellular alterations caused by this treatment are little known. Alterations in expression in surface glycoproteins and glycolipids are significant features in malignant tumor transformation and are strongly associated with tumor cell adhesion, invasion, and metastasis. This study evaluated photodynamic therapy effects on indirect distribution surface glycoproteins in human laryngeal carcinoma HEp-2 cell line surface, using Click-iT™ Metabolic Glycoprotein Labeling Reagent. Aluminum Phthalocyanine Tetrasulfonate (AlPcS4) was administrated at 5 μM/mL, followed by one hour of the incubation period for its accumulation in the tumor cells. After this time, cultures were irradiated with LED (light-emitting diode) dispositive (BioPdi/IRRAD-LED) λ = 660 nm. Evaluation of glycoproteins was performed by flow cytometry. Knowledge of the cellular alterations caused by the treatment will allow obtaining tools for the potentiation or optimization and personalization of the anticancer treatment. This therapy has a low cost and better efficacy, when applied early, about radiotherapy chemotherapy.
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Mee, Nicholas. "Ripples in the Fabric of Things". W Gravity: From Falling Apples to Supermassive Black Holes, 246–78. Wyd. 2. Oxford University PressOxford, 2022. http://dx.doi.org/10.1093/oso/9780192845283.003.0009.
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Abstract This chapter is about gravitational waves. It discusses the Hulse–Taylor binary neutron star system and its importance in testing general relativity and the discovery that the system is losing energy by emitting gravitational waves. The chapter looks at the history of gravitational wave detectors, culminating in the construction of the Advanced LIGO interferometer. The detection of the first gravitational wave signal is discussed in detail along with an analysis of the system that produced the gravitational wave. The text discusses the significance of this new window on the universe. The detection of neutron star mergers has offered an insight into how heavy elements such as gold are created. The detection of black hole mergers has given the most direct evidence for the existence of stellar mass black holes and has confirmed that gravitational waves travel at the speed of light. The chapter closes by looking at future gravitational wave observatories.
Streszczenia konferencji na temat "Light emitting elements"
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Donie, Yidenekachew J., Lorenz Graf Van Reventlow, Jan B. Preinfalk, Somayeh Moghadamzadeh, Jocelyn Van Leeuwen, Tsvetelina Merdzhanova, Karsten Bittkau i in. "Low- and high-index self-assembled nanopillars as light outcoupling elements in organic light emitting diodes". W Optical Devices and Materials for Solar Energy and Solid-state Lighting. Washington, D.C.: OSA, 2019. http://dx.doi.org/10.1364/pvled.2019.pw1c.3.
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Hoch, John S., Annette Grot, T. S. Tan i Joseph M. Kahn. "Diffractive Spot-Array Generation Using Multimode Surface-Emitting Lasers and Light-Emitting Diodes". W Diffractive Optics and Micro-Optics. Washington, D.C.: Optica Publishing Group, 1996. http://dx.doi.org/10.1364/domo.1996.dmd.3.
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The ability to shape the diverging beam from a surface-emitting laser or a light-emitting diode is important for future micro-optic illumination systems. In this paper, we consider using two surface-relief diffractive optical elements (DOEs) to shape the output from a 980-nm multimode vertical-cavity surface-emitting laser (VCSEL) into a closely spaced rectangular spot array in the near field (approximately 10 mm from the laser). We also describe a similar system for illumination by an 850-nm resonant-cavity light-emitting diode (RCLED). With small intensity variation from spot to spot, the rectangular spot array is intended to approximate a profile that is completely uniform from point to point. This design strategy is particularly valuable with the VCSEL, as its complicated multimode emission profile makes it nearly impossible to guarantee absolute uniformity within the rectangle, but creating a rectangular array of light spots spaced very close together is still feasible.
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Jewell, J. L., A. Scherer, Y. H. Lee, S. L. McCall, J. P. Harbison, L. T. Florez, R. S. Tucker, C. A. Burrus, C. J. Sandroff i N. A. Olsson. "Vertical cavity surface-emitting microlasers". W OSA Annual Meeting. Washington, D.C.: Optica Publishing Group, 1990. http://dx.doi.org/10.1364/oam.1990.mkk2.
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Electrically driven microlasers are attractive as elements of photonic switches, photonic chip-to-chip communications systems, or matrix-addressable light source arrays. Fabrication of more than one million lasers on a <1 cm chip, submilliampere threshold, 8-GHz modulation, and more recent progress will be discussed.
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Dalton, Larry R. "Organic Optical Materials: An Overview of Scientific Issues and Applications". W Solid State Lasers: Materials and Applications. Washington, D.C.: Optica Publishing Group, 1997. http://dx.doi.org/10.1364/sslma.1997.tha1.
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Although historically, organic materials have not been thought of as optical materials, organics are experiencing increased use as both passive and active optical components. Applications range from passive elements such as gratings, fibers, interconnects, lens, and prisms to active components such as light emitting diodes, electro-optic modulators, solid-state lasers, frequency doublers, optical memories, and sensor protection elements. The utilization of organic materials has typically involved competition with established technology based on inorganic materials. For example, polymeric optical fibers must compete with established silica fiber technology, polymeric electro-optic modulators must compete with established lithium niobate technology, organic light emitting diodes with a host of inorganic light emitting materials, etc. Unless organics offer special advantages, they have little chance of market penetration. A frequently quoted putative general advantage of organics, and particularly polymeric materials, is their processibility and low cost. In areas such as discrete passive components, this advantage clearly comes into play and has resulted with wide commercial use. Indeed, inorganic materials such as sol-gel glasses have major difficulty in competing with polymeric materials in the manufacture of passive discrete optical components. For applications, such as electro-optic modulators and light emitting diodes, the success of organics depends on a number of properties other than materials cost or processibility although even here processibility can be an important consideration for issues such as integration with semiconductor VLSI electronics.
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Liu, Hua-Kuang, i Tien-Hsin Chao. "On the Progress of the Liquid Crystal Television Spatial Light Modulator". W Spatial Light Modulators and Applications. Washington, D.C.: Optica Publishing Group, 1988. http://dx.doi.org/10.1364/slma.1988.thd1.
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The pocket-sized liquid crystal televisions recently marketed by several Japanese companies have been welcome gifts among friends and found useful in applications such as the view-finders in video cameras. Many optical processing researchers have also begun to use these devices as a spatial light modulators (SLM's) in a variety of ways. It has been demonstrated that LCTV's can be used as optical input devices, logic elements, computer generated hologram recordings, and 2-D phase image representations. The LCTV may be used for these processing applications because it has several attractive features. For example, it is electronically addressable through a microcomputer, and since it is a TV by design, it is naturally addressable by a TV camera and it can be refreshed at a speed of 30 Hz. By definition, when the LCTV is used as a SLM, it can be controlled remotely by an emitting antenna anywhere in the world. So one can imagine that a joint experiment on optical processing could be performed by researchers from Asia, Europe, and the United States through the TV transmitter and receiver linkage. The speed of 30 frames/sec. is sufficient for the present usage because the inputting of image signals from a computer can hardly exceed this speed.
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Bolgov, Sergej S., Victor A. Botte, Lyudmila I. Konopaltseva, Victor I. Pipa i Anna P. Savchenko. "Methods of testing light-emitting elements and devices for middle- and far-IR spectral regions based on negative luminescence phenomena". W International Conference on Optical Diagnostics of Materials and Devices for Opto-, Micro-, and Quantum Electronics, redaktorzy Sergey V. Svechnikov i Mikhail Y. Valakh. SPIE, 1995. http://dx.doi.org/10.1117/12.226200.
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Oh, Tae K., i Nicholas Caviris. "Real-time rf spectrum analyzer using a surface-emitting microlaser array". W OSA Annual Meeting. Washington, D.C.: Optica Publishing Group, 1991. http://dx.doi.org/10.1364/oam.1991.thhh5.
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A new type of real-time optical rf spectrum analyzer is proposed that mainly consists of a 1-D surface-emitting microlaser array, a sampling and hold circuit (S/H), and a CCD photodectector. An rf input signal is sampled by the S/H within a frame time of the system, and the sampled values are output to the matrix-addressed microlaser array in parallel. Using this scheme, the light intensity distributions are equivalent to the sampled values of the rf signal. The light distributions are then Fourier transformed and processed with a low-pass filter to remove the periodicity of the laser array. The output of the photodetector is proportional to the power spectrum content of the rf input. This architecture has the advantage of adjustable thresholding capability for the input signal by biasing a dc voltage to the common negative of the microlaser array. The system’s time–bandwidth product is limited by the number of microlaser elements in the array. The resolution and speed of the system are dependent upon the data rate and number of pixels of the photodetector, the sampling frequency of the S/H, and the number of microlasers.
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Yoshikawa, T., H. Kosaka, K. Kurihara, M. Kajita, Y. Sugimoto i K. Kasahara. "Complete Polarization Control of 8x8 Vertical-cavity Surface-emitting Laser Matrix Arrays". W Quantum Optoelectronics. Washington, D.C.: Optica Publishing Group, 1995. http://dx.doi.org/10.1364/qo.1995.qfb5.
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Polarization control in vertical-cavity surface-emitting lasers (VCSELs) is important because the devices in which VCSELs are used, such as magneto-optical discs or optical interconections, often use polarization-sensitive elements such as beam spliters. Additionally, a great advantage of VCSELs is that they can readily be used to form arrays; thus, polarization must be controlled for not only single VCSELs but also VCSEL arrays. However, since the VCSEL polarization direction is not determined, the polarization direction of the emitted light is random. In previous works, efforts have been made to control polarization, however, polarization still remains uncontrolled, especially in array form1-3.
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Gimkiewicz, Ch, D. Hagedorn, J. Jahns, E. B. Kley i F. Thoma. "Fabrication of microprisms for planar-optical interconnections using analog gray-scale lithography with high energy beam sensitive glass". W Diffractive Optics and Micro-Optics. Washington, D.C.: Optica Publishing Group, 1998. http://dx.doi.org/10.1364/domo.1998.dtud.24.
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Integrated planar free-space optics is a viable concept for building compact systems for interconnection and sensor applications. Micro-optical elements are integrated on a single substrate to guide the light signals traveling inside the substrate [1]. Optoelectronic devices are bonded on the substrate by hybrid integration techniques such as flip-chip bonding. For interconnection applications, vertical-cavity surface emitting laser diodes (VCSELs) are of particular interest as fast 2-D input arrays.
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Mennerat, Sophie, i Sylvain Paineau. "A novel design of diffractive optical interconnects for multichip clock distribution". W The European Conference on Lasers and Electro-Optics. Washington, D.C.: Optica Publishing Group, 1998. http://dx.doi.org/10.1364/cleo_europe.1998.cpd2.3.
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We report a novel system of diffractive optical interconnects for very high speed clock distribution among multichip modules. Our system distributes two clock signals, each from one separate Vertical Cavity Surface Emitting Laser (VCSEL) over four PIN diodes positioned within a radius of 9 mm along a light-guiding glass plate. The incoming optical gaussian beams from VCSEL are splitted by diffractive optical elements into four output beams and the glass plate propagates the light through multiple reflections onto the golden metallized faces towards the detectors. The overall alignment and chromatic acceptance is highly improved by the use of SELFOC micro-lenses that collimate the laser beam onto the diffractive optical element and that focus the output beam onto the active area of the detectors. The proposed architecture allows tolerance on the light source wavelength as high as Δλ = 10 nm and global tolerances of assembly of the glass plate of 1.5 degrees in rotation and 10 µm in translation making it compatible with the processes of hybridization in microelectronics.