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Journal articles on the topic 'Light emitting elements'

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Author: Grafiati

Published: 6 September 2023

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1

Yulaeva, Yulia, Artem Khomyakov, and Vasily Tuev. "A decomposition optical-mechanical model of a led emitting element." Science Bulletin of the Novosibirsk State Technical University, no. 4 (December 18, 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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2

Zhang, H. X., E. Gu, C. W. Jeon, Z. Gong, M. D. Dawson, M. A. A. Neil, and P. M. W. French. "Microstripe-array InGaN light-emitting diodes with individually addressable elements." IEEE Photonics Technology Letters 18, no. 15 (August 2006): 1681–83. http://dx.doi.org/10.1109/lpt.2006.879926.

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3

Kim, D. Y., D. Vak, J. Jo, J. Ghim, C. Chun, B. Lim, and A. Heeger. "Polymers for Light-Emitting Devices with Integrated Hole-Transporting Elements." Synfacts 2006, no. 12 (December 2006): 1236. http://dx.doi.org/10.1055/s-2006-955588.

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4

Hansen, Eric C., Yun Liu, Hendrik Utzat, Sophie N. Bertram, Jeffrey C. Grossman, and Moungi G. Bawendi. "Blue Light Emitting Defective Nanocrystals Composed of Earth‐Abundant Elements." Angewandte Chemie International Edition 59, no. 2 (January 7, 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, and Moungi G. Bawendi. "Blue Light Emitting Defective Nanocrystals Composed of Earth‐Abundant Elements." Angewandte Chemie 132, no. 2 (December 3, 2019): 870–77. http://dx.doi.org/10.1002/ange.201911436.

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6

Bumai, Yurii, Aleh Vaskou, and Valerii Kononenko. "Measurement and Analysis of Thermal Parameters and Efficiency of Laser Heterostructures and Light-Emitting Diodes." Metrology and Measurement Systems 17, no. 1 (January 1, 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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7

Yu, Chao, Yifan Peng, Tianyi Guo, Qiang Fu, Haifeng Li, and Xu Liu. "Beam shaping for multicolour light-emitting diodes with diffractive optical elements." Journal of Modern Optics 64, no. 4 (October 6, 2016): 388–95. http://dx.doi.org/10.1080/09500340.2016.1240251.

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8

Caldiño, Ulises, Marco Bettinelli, Maurizio Ferrari, Elisa Pasquini, Stefano Pelli, Adolfo Speghini, and Giancarlo C. Righini. "Rare Earth Doped Glasses for Displays and Light Generation." Advances in Science and Technology 90 (October 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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9

Parkova, Inese, Ivars Parkovs, and Ausma Vilumsone. "Light-emitting textile display with floats for electronics covering." International Journal of Clothing Science and Technology 27, no. 1 (March 2, 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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10

Kim, Hyeonbin, Jinho Keum, and Moon Sung Kang. "NIR Light-Emitting Devices Based on Ligand-Crosslinked CuInS2/ZnS Quantum Dot Emissive Layer." Journal of Flexible and Printed Electronics 2, no. 1 (June 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.

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11

Himmelstoss, F. A., and M. Windisch. "A capacitor-free driving stage for light emitting diodes." Renewable Energy and Power Quality Journal 21, no. 1 (July 2023): 220–25. http://dx.doi.org/10.24084/repqj21.278.

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Electrolytic capacitors have the disadvantage of pronounced aging. Non-electrolytic capacitors are therefore used in applications where long-life is important. In this paper we present a driving stage for LEDs without any capacitive elements. The basic topology is a Buck converter with one coil, one active, and one passive switch. Instead of the output capacitor, series connections of one or more LEDs and an active switch are connected. An additional diode is connected between the output and the input to achieve a current path, when all LEDpaths are off. A nonlinear hysteresis controller is used to achieve a robust control. A system with three switchable LED-strings is analyzed. Design hints are given and the function is proved with the help of LTSpice simulations. The system can be used for lighting purposes with the possibility to change the chrominance. The potentiality to transmit data is also treated.

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Vaštakaitė-Kairienė, V., A. Brazaitytė, A. Viršilė, G. Samuolienė, J. Miliauskienė, J. Jankauskienė, and P. Duchovskis. "Pulsed light-emitting diodes for higher contents of mineral elements in mustard microgreens." Acta Horticulturae, no. 1271 (February 2020): 149–54. http://dx.doi.org/10.17660/actahortic.2020.1271.21.

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13

AMANO, Yohei, and Hiroshji IGARASHI. "High Speed and high resolution Gaze Tracking System with Multiple Light-emitting Elements." Proceedings of JSME annual Conference on Robotics and Mechatronics (Robomec) 2016 (2016): 1P1–12a6. http://dx.doi.org/10.1299/jsmermd.2016.1p1-12a6.

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14

AMANO, Yohei, and Hiroshi IGARASHI. "High Speed and high resolution Gaze Tracking System with Multiple Light-emitting Elements." Proceedings of JSME annual Conference on Robotics and Mechatronics (Robomec) 2017 (2017): 2P2—M09. http://dx.doi.org/10.1299/jsmermd.2017.2p2-m09.

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15

Kikuta, Hisao, Shunsuke Hino, Akira Maruyama, and Akio Mizutani. "Estimation method for the light extraction efficiency of light-emitting elements with a rigorous grating diffraction theory." Journal of the Optical Society of America A 23, no. 5 (May 1, 2006): 1207. http://dx.doi.org/10.1364/josaa.23.001207.

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16

Chiu, Chien-Liang, Meng-Syun Lin, and Yi-Chen Wu. "Hermetic Seal of Organic Light Emitting Diode with Glass Frit." Molecules 27, no. 1 (December 23, 2021): 76. http://dx.doi.org/10.3390/molecules27010076.

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The components of OLED encapsulation with hermetic sealing and a 1026-day lifetime were measured by PXI-1033. The optimal characteristics were obtained when the thickness of the TPBi layer was 20 nm. This OLED obtained a maximum luminance (Lmax) of 25,849 cd/m2 at a current density of 1242 mA/cm2, an external quantum efficiency (EQE) of 2.28%, a current efficiency (CE) of 7.20 cd/A, and a power efficiency (PE) of 5.28 lm/W. The efficiency was enhanced by Lmax 17.2%/EQE 0.89%/CE 42.1%/PE 41.9%. The CIE coordinates of 0.32, 0.54 were all green OLED elements with wavelengths of 532 nm. The shear strain and leakage test gave results of 16 kgf and 8.92 × 10−9 mbar/s, respectively. The reliability test showed that the standard of MIL-STD-883 was obtained.

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17

Rebohle, L., and Wolfgang Skorupa. "MOS Light Emitting Devices Based on Rare-Earth Ion Implantation." Materials Science Forum 590 (August 2008): 117–38. http://dx.doi.org/10.4028/www.scientific.net/msf.590.117.

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In this article we will give an overview of our work devoted to Si-based light emission which was done in the last years. Si-based light emitters were fabricated by ion implantation of rare earth elements into the oxide layer of a conventional MOS structure. Efficient electroluminescence was obtained for the wavelength range from UV to the visible by using a transparent top electrode made of indium-tin oxide. In the case of Tb-implantation the best devices reach an external quantum efficiency of 16 % which corresponds to a power efficiency in the order of 0.3 %. The properties of the microstructure, the IV characteristics and the electroluminescence spectra were evaluated. The electroluminescence was found to be caused by hot electron impact excitation of rare earth ions, and the electric phenomena of charge transport, luminescence centre excitation, quenching and degradation are explained in detail.

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18

Qi, Xiangfei, Michael Slootsky, and Stephen Forrest. "Stacked white organic light emitting devices consisting of separate red, green, and blue elements." Applied Physics Letters 93, no. 19 (November 10, 2008): 193306. http://dx.doi.org/10.1063/1.3021014.

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19

Kolesnyk, A. "Optical System for Led Luminaire." Metrology and instruments, no. 4 (September 7, 2019): 62–67. http://dx.doi.org/10.33955/2307-2180(4)2019.62-67.

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Lighting devices are an important element of a large number of technical systems, including road, living, industrial lighting, lighting systems of vehicles. It is known that the light instrument must fulfill two basic lighting tasks: to redistribute the light source of light source in the right way and to limit its dazzling effect. The introduction of light-emitting diodes (LEDs) for lighting necessitated a completely new quality in the construction of luminaires. The different production technology required new methods and designing tools. It also challenged designers with new problems to solve. LEDs are light sources emitting in one hemisphere, which requires a special approach to designing an LED lighting unit. However, for the illumination of premises with high spans or streets, roads such a light distribution is not suitable. For luminaires with solid-state light sources, other materials and new technology must be used; moreover, light distribution needs to be formed using different methods. This paper presents the design process of a LED luminaire from concept to implementation, exemplified by road lighting, and describes the methods and procedures used by the designer. Also, technological problems influencing the quality of the above lighting are addressed. Optical systems for LEDs are considered. The peculiarities of the use of secondary optical elements in the form of lenses for purpose of obtaining different diagrams of the spatial distribution of light intensity of light-emitting diodes are analyzed. Features and problems of calculation of secondary optical systems are considered. Massive collimators do not have to be elements that focus a narrow beam of light. They are able to form a beam in accordance with any accepted distribution that is appropriate for a given application. They are also able to form a beam in a specific way that is required for outdoor lighting luminaires. The stages of a project for designing a road luminaire require the application of the knowledge and experience gained in various research projects. The design methods described in this paper have been developed designing activity and are also to be used successfully in lighting production.

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20

Łężak, Krzysztof, and Agnieszka Greszta. "Active luminous elements in the high visibility clothing and EU conformity assessment." Occupational Safety – Science and Practice 573, no. 6 (June 19, 2019): 6–11. http://dx.doi.org/10.5604/01.3001.0013.2409.

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The insufficient, individual visibility of employees in various work environments and road traffic participants (e.g. in the night conditions, during bad weather), is still one the main causes of road accidents involving pedestrians, and collisions between people and machines. Both in professional and non-professional activities, the use of high visibility (warning) clothing and reflective elements seems to be the only way to increase the individual visibility of a human. A dynamically developing market of various types of non-incadescent light sources with small size, often flexible, emitting light with different colors and photometric parameters allows the application of these luminous elements to the warning clothing. The article presents examples of electroluminescent light sources (LED diodes, El wire, El tape, El panel) and optical fibers applied in the warning clothing. The analysis of the current detailed normative requirements and the legal status regarding the use of warning clothing with active light sources indicates that they are not sufficient to carry out the tests and EU conformity assessment of this type of protective clothing.

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21

Zhang, Fei, Zhuangzhuang Ma, Zhifeng Shi, Xu Chen, Di Wu, Xinjian Li, and Chongxin Shan. "Recent Advances and Opportunities of Lead-Free Perovskite Nanocrystal for Optoelectronic Application." Energy Material Advances 2021 (February 5, 2021): 1–38. http://dx.doi.org/10.34133/2021/5198145.

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Metal halide perovskite nanocrystals (NCs), as a new class of light-emitting and light-harvesting materials, have recently attracted intensive attention for an impressive variety of optoelectronic applications. However, the lead toxicity and poor stability of such materials severely restrict their practical applications and future commercialization. Lead-free perovskite NCs and their derivatives, designed by the reasonable chemical substitution of Pb with other nontoxic elements, are recently booming as an attractive alternative to lead-based counterparts. In this review, we firstly present a comprehensive overview of currently explored lead-free perovskite NCs with an emphasis on their design routes, morphologies, optoelectronic properties, and environmental stability issues. Then, we discuss the preliminary achievements of lead-free perovskite NCs in versatile optoelectronic applications, such as light-emitting devices, solar cells, photodetectors, and photocatalysis. We finish this review with a critical outlook into the currently existing challenges and possible development opportunities of this rapidly evolving field.

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22

Simakina, Ya I., I. I. Kuzmin, Yu I. Fabelinsky, and T. Kh Chyong. "MANGANESE(II) DETERMINATION BY DIFFUSE REFLECTANCE SPECTROSCOPY." Fine Chemical Technologies 12, no. 5 (October 28, 2017): 47–55. http://dx.doi.org/10.32362/2410-6593-2017-12-5-47-55.

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Results of testing a prototype light-emitting diod miniphotometer for rapid and sensitive elements determination both in laboratory and in field conditions are presented. The new photometer consists of two devices providing measurements of absorbance and diffuse reflectance, having a joint system of data management, registration and presentation of the results. The measurements of absorbance were registered in the visible spectrum. The explored reaction of Mn(II) with 1-(2-pyridylazo)-2-naphthol and the new reaction with 2-(2-quinolinazo)-5-diethylaminophenol were used to verify the device’s metrological parameters. Spectra obtained by means of the proposed photometer were compared to those for commercial photometers. A computer algorithm considering the difference in light-emitting intensity between diods was developed. The possibility of determination down to 1 mkg/ml metal ions in liquid samples was shown.

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23

Zeng, Xi, Yosuke Mizuno, and Kentaro Nakamura. "Sound intensity probe for ultrasonic field in water using light-emitting diodes and piezoelectric elements." Japanese Journal of Applied Physics 56, no. 12 (November 9, 2017): 127301. http://dx.doi.org/10.7567/jjap.56.127301.

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24

TANAKA, Keigo, Masaya SHIGETA, Hisaya KOMEN, and Manabu TANAKA. "Identification of light emitting elements around tungsten electrode during TIG welding using optical emission spectroscopy." QUARTERLY JOURNAL OF THE JAPAN WELDING SOCIETY 39, no. 4 (2021): 248–59. http://dx.doi.org/10.2207/qjjws.39.248.

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25

Su, Ping, Pengli An, Jianshe Ma, Lixiang Han, Zhenbo Ren, Jie Mao, Liangcai Cao, and Guofan Jin. "Demonstration of an Autostereoscopic Three-Dimensional Light-Emitting Diode Display Using Diffractive Optical Elements Sheet." Journal of Display Technology 11, no. 11 (November 2015): 953–58. http://dx.doi.org/10.1109/jdt.2014.2382295.

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26

Krestnikov, Igor L., V. V. Lundin, A. V. Sakharov, D. A. Bedarev, E. E. Zavarin, Yu G. Musikhin, N. M. Shmidt, et al. "Heterostructures based on nitrides of group III elements: technical processes, properties, and light-emitting devices." Physics-Uspekhi 44, no. 8 (August 31, 2001): 815–16. http://dx.doi.org/10.1070/pu2001v044n08abeh000968.

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27

Krestnikov, Igor L., V. V. Lundin, A. V. Sakharov, D. A. Bedarev, E. E. Zavarin, Yu G. Musikhin, N. M. Shmidt, et al. "Heterostructures based on nitrides of group III elements: technical processes, properties, and light-emitting devices." Uspekhi Fizicheskih Nauk 171, no. 8 (2001): 857. http://dx.doi.org/10.3367/ufnr.0171.200108e.0857.

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28

Chien, Forest Shih-Sen, Riza Ariyani Nur Khasanah, Pei-Te Lin, Yen-Fu Lin, and Yuen-Wuu Suen. "Impedance Elements of Significant Junctions in InGaN Light-Emitting Diodes Studied by Electric Modulus Spectroscopy." IEEE Transactions on Electron Devices 66, no. 8 (August 2019): 3393–98. http://dx.doi.org/10.1109/ted.2019.2921393.

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29

Gu, Huarong, Mengzhu Chen, Qixia Wang, and Qiaofeng Tan. "Design of two-dimensional diffractive optical elements for beam shaping of multicolor light-emitting diodes." Applied Optics 57, no. 10 (March 30, 2018): 2653. http://dx.doi.org/10.1364/ao.57.002653.

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30

Choi, Pyuck-Pa, Oana Cojocaru-Mirédin, Daniel Abou-Ras, Raquel Caballero, Dierk Raabe, Vincent S. Smentkowski, Chan Gyung Park, et al. "Atom Probe Tomography of Compound Semiconductors for Photovoltaic and Light-Emitting Device Applications." Microscopy Today 20, no. 3 (May 2012): 18–24. http://dx.doi.org/10.1017/s1551929512000235.

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Compound semiconductors belong to the most important materials for optoelectronic applications. Many of them exhibit favorable optical properties, such as a direct energy band gap (in contrast to silicon) and high-absorption coefficients over a wide spectral range. Moreover, varying the composition of the compound or substituting some of its elements often allows for controlled band gap engineering and optimization for specific applications. Because many compound semiconductors enable efficient conversion of light into electricity and vice versa, they are commonly used materials for optoelectronic devices.

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31

Park, Da-Young, Jae-Hoon Lim, Mi-Young Ha, and Dae-Gyu Moon. "High Efficiency Quantum Dot Light-Emitting Diode by Solution Printing of Zinc Oxide Nanoparticles." Journal of Nanoscience and Nanotechnology 20, no. 7 (July 1, 2020): 4454–57. http://dx.doi.org/10.1166/jnn.2020.17591.

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Quantum dot light-emitting diodes (QLEDs) have attracted considerable attention owing to the narrow emission spectra, wide color gamut, high quantum yield and size-controlled emission wavelength. Zinc oxide nanoparticles have been widely used as an electron transport layer (ETL) in QLEDs due to their excellent electrical properties. In this study, we compared the efficiency of QLEDs with organic and zinc oxide ETLs in viewpoint of the charge balance. The QLEDs were constructed using ZnO nanoparticles with an average particle size of 3 nm or 3TPYMB as the ETL materials. CdSe/ZnS quantum dots and poly-TPD were used as a light-emitting elements and hole transporting material, respectively. The QLED with 3TPYMB ETL exhibited current efficiency of 7.71 cd/A, while the efficiency of the QLED using ZnO nanoparticles was significantly improved to 38.76 cd/A. Such a substantial improvement of emission efficiency in the QLEDs with ZnO ETL was attributed to the much better charge balance by the ZnO.

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32

Barickman, T. Casey, Dean A. Kopsell, Carl E. Sams, and Robert C. Morrow. "Sole-Source LED Lighting and Fertility Impact Shoot and Root Tissue Mineral Elements in Chinese Kale (Brassica oleracea var. alboglabra)." Horticulturae 6, no. 3 (July 18, 2020): 40. http://dx.doi.org/10.3390/horticulturae6030040.

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The current study investigated the impacts of light quality and different levels of fertility on mineral nutrient concentrations in the shoot and root tissues of Chinese kale (Brassica oleracea var. alboglabra). “Green Lance” Chinese kale was grown under: (1) fluorescent/incandescent light; (2) 10% blue (447 ± 5 nm)/90% red (627 ± 5 nm) light emitting diode (LED) light; (3) 20% blue/80% red LED light; and (4) 40% blue/60% red LED light as sole-source lighting at two different levels of fertility. All plants were harvested 30 days after seeding and shoot and root tissues were analyzed for mineral nutrients. Lighting and fertility interacted to influence kale shoot and root mineral nutrient concentrations. The results indicate that sole-source LED lighting used in production can impact the mineral nutritional values of baby leafy greens now popular for the packaged market. This is evident in the current and previous studies in which lighting affects biomass and indirectly affects mineral nutrient concentrations.

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33

Lou, Ya Zhou, Xiao Xia Sun, and Ying Chun Li. "The New Synthesis of Novel Organic Light-Emitting Material Spirobifluorene by Ullman Coupling." Applied Mechanics and Materials 204-208 (October 2012): 4051–54. http://dx.doi.org/10.4028/www.scientific.net/amm.204-208.4051.

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A mide, simple and efficient synthetic procedure for the preparation of 2,7-dibromo-2′,3′,6′,7′-tetra(2-methylbutyloxy)spirobifluorene and key intermediates, tetra(2-methlbutyloxy)biphenyl ，2-bromo-4,5,3′,4′-tetra(2-methylbutyloxy)biphenyl, 2,7-Dibromo-2′,6,3′,7′--tetra(2-methylbutyloxy)biphenyl-9-Fluorenol, has been developed. The procedure described herein offers several advantages, including high product yields, easy purification, and large scale production. Ether protected 2,7-dibromo-9,9′-spirobifluorene has good solubility in organic aolvents to permit an appropriate coating process, ability to achieve various colors so as to make full color display elements possible.

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Wang, Yadi, Masanobu Haraguchi, Xingbo Zhang, Pingping Wang, and Shufeng Sun. "Improvement of Optical Confinement for Terahertz Vertical-Cavity Surface-Emitting Laser with Square-Lattice Photonic Crystal Structure." Coatings 13, no. 6 (May 23, 2023): 972. http://dx.doi.org/10.3390/coatings13060972.

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A new method proposed to enhance the optical confinement of the terahertz band in a vertical cavity surface emitting laser involves introducing a square-lattice photonic crystal structure. This structure’s filling factor was optimized by computing the energy band structure and optical band values of the photonic crystal. The optimal optical band value is 0.436–0.528 a/λ. At a specific carrier concentration, the real part of dielectric constant of GaAs/AlGaAs materials will gradually increase with the increase of Al elements. By adjusting the length of the resonant cavity, a vertical cavity surface emitting laser with two wavelengths can be created without utilizing current injection. Additionally, the photonic crystal structure’s control effect on the transverse mode of the vertical cavity surface emitting laser and the release effect of the PN junction light confinement were analyzed. Numerical calculations indicated that incorporating a cubic photonic crystal structure in the vertical cavity surface emitting laser resulted in a 2× increase in the difference frequency intensity and a 6.33× increase in the optical field intensity.

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35

Suyal, H., A. J. Waddie, A. R. Mackintosh, A. J. C. Kuehne, M. R. Taghizadeh, R. A. Pethrick, A. McCarthy, et al. "Light emitting polymer blends and diffractive optical elements in high-speed direct laser writing of microstructures." Journal of Physics D: Applied Physics 41, no. 9 (April 4, 2008): 094009. http://dx.doi.org/10.1088/0022-3727/41/9/094009.

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Nicolics, Johann, Paul Fulmek, Wolfgang Nemitz, and Franz P. Wenzl. "Analysis of the local temperature distribution in color conversion elements of phosphor converted light-emitting diodes." International Journal of Heat and Mass Transfer 116 (January 2018): 1096–107. http://dx.doi.org/10.1016/j.ijheatmasstransfer.2017.09.088.

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Fulmek, Paul, Christian Sommer, Paul Hartmann, Peter Pachler, Hans Hoschopf, Gregor Langer, Johann Nicolics, and Franz P. Wenzl. "On the Thermal Load of the Color-Conversion Elements in Phosphor-Based White Light-Emitting Diodes." Advanced Optical Materials 1, no. 10 (July 30, 2013): 753–62. http://dx.doi.org/10.1002/adom.201300207.

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Simegnaw, Abdella Ahmmed, Benny Malengier, Melkie Getnet Tadesse, and Lieva Van Langenhove. "Development of Stainless Steel Yarn with Embedded Surface Mounted Light Emitting Diodes." Materials 15, no. 8 (April 14, 2022): 2892. http://dx.doi.org/10.3390/ma15082892.

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The integration of electronic components in/onto conductive textile yarns without compromising textile qualities such as flexibility, conformability, heat and moisture transfer, and wash resistance is essential to ensuring acceptance of electronic textiles. One solution is creating flexible and stretchable conductive yarns that contain tiny surface-mounted electronic elements embedded at the fiber level. The purpose of this work was to manufacture and subsequently evaluate the physical features and electromechanical properties of stainless steel yarn with light-emitting surface mounted devices (SMDs) embedded in it. The SMDs were successfully integrated into a conductive stainless steel yarn (SS) by inserting crimp beads and creating a bond through hot air soldering machines, resulting in what we call an E-yarn. The relationship curves between gauge length and electrical resistance, and the relationship curves between conductive yarn elongation and electrical resistance, were explored experimentally. The results of the analysis demonstrated that E-yarn had a lower tensile strength than the original electrically-conductive SS yarn. The effects of the washing cycle on the conductivity of the E-yarn were also investigated and studied. The results showed that E-yarns encapsulated at the solder pad by heat shrink tube still functioned well after ten machine wash cycles, after which they degraded greatly.

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Tepikina, Anna V., and Svetlana G. Vlasova. "Inorganic Composites Luminophors in Lithium-Borate Glasses with Rare-Earth Elements for White-Emitting Diodes." Defect and Diffusion Forum 410 (August 17, 2021): 764–69. http://dx.doi.org/10.4028/www.scientific.net/ddf.410.764.

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The paper describes the synthesis of novel luminescent composite system, based on lithium-borate glass matrix with addition of rare-earth elements and yttrium-aluminum garnet finely divided powder. The new chemical composition of glass has been selected, composite’s fabrication technology was developed, the temperature conditions of glass and luminophore sintering as well. The spectral characteristics of the obtained luminescent composites are measured, and chromaticity diagrams are considered. The radiation spectra showed a maximum of about 560 nm, the maximum spectral intensity of the radiation is about 90 μw/cm2/nm. Powerful energy saving source of white light was produced.

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Ide, Keisuke, Naoto Watanabe, Takayoshi Katase, Masato Sasase, Junghwan Kim, Shigenori Ueda, Koji Horiba, et al. "Low-temperature-processable amorphous-oxide-semiconductor-based phosphors for durable light-emitting diodes." Applied Physics Letters 121, no. 19 (November 7, 2022): 192108. http://dx.doi.org/10.1063/5.0115384.

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In this study, we fabricated light-emitting diodes (LEDs) on glass substrates at a maximum process temperature of 200 °C using amorphous oxide semiconductor (AOS) materials as emission layers. Amorphous gallium oxide films doped with rare-earth elements (Eu, Pr, and Tb) were employed as AOS emission layers, and the LEDs emitted clear red, green, and pink luminescence upon direct-current application even in the ambient environment. Resonance photoelectron spectroscopy revealed the difference in the electronic structure of the films for each rare-earth dopant, suggesting different emission mechanisms, viz., electron–hole recombination and impact excitation. Although it is widely believed that amorphous materials are unsuitable for use as emission layers of LEDs because of their high concentrations of mid-gap states and defects, the developed rare-earth-doped AOS materials show good performance as emission layers. This study provides opportunities for the advancement of flexible display technologies operating in harsh environments.

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Das, Aparna. "A Systematic Exploration of InGaN/GaN Quantum Well-Based Light Emitting Diodes on Semipolar Orientations -=SUP=-*-=/SUP=-." Оптика и спектроскопия 130, no. 3 (2022): 376. http://dx.doi.org/10.21883/os.2022.03.52165.1549-21.

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Light-emitting diodes (LEDs) based on group III-nitride semiconductors (GaN, AlN, and InN) are crucial elements for solid-state lighting and visible light communication applications. The most widely used growth plane for group III-nitride LEDs is the polar plane (c-plane), which is characterized by the presence of a polarization-induced internal electric field in heterostructures. It is possible to address long-standing problems in group III-nitride LEDs, by using semipolar and nonpolar orientations of GaN. In addition to the reduction in the polarization-induced internal electric field, semipolar orientations potentially offer the possibility of higher indium incorporation, which is necessary for the emission of light in the visible range. This is the preferred growth orientation for green/yellow LEDs and lasers. The important properties such as high output power, narrow emission linewidth, robust temperature dependence, large optical polarization ratio, and low-efficiency droop are demonstrated with semipolar LEDs. To harness the advantages of semipolar orientations, comprehensive studies are required. This review presents the recent progress on the development of semipolar InGaN/GaN quantum well LEDs. Semipolar InGaN LED structures on bulk GaN substrates, sapphire substrates, free-standing GaN templates, and on Silicon substrates are discussed including the bright prospects of group III-nitrides. Keywords: Group III-nitride semiconductor, semipolar, light-emitting diodes, InGaN/GaN quantum well.

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Yang, Xiaolong, Guijiang Zhou, and Wai-Yeung Wong. "Functionalization of phosphorescent emitters and their host materials by main-group elements for phosphorescent organic light-emitting devices." Chemical Society Reviews 44, no. 23 (2015): 8484–575. http://dx.doi.org/10.1039/c5cs00424a.

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Singh, Sonika, Annu Dalal, Mahesh Kumar, and Deepika Dhaterwal. "Structural and Luminescence Analysis of Low Temperature Solution Combustion Derived White Light Emitting Y2(1-x)Dy2xZr2O7 Nanophosphors for WLEDs." Asian Journal of Chemistry 35, no. 4 (2023): 1019–24. http://dx.doi.org/10.14233/ajchem.2023.27019.

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White light emitting dysprosium doped rare-earth zirconate Y2(1-x)Dy2xZr2O7 (x = 0.5 to 5 mol%) crystalline phosphors in nano-regime were obtained using urea supported solution combustion methodology at low temperature 650 ºC. Presence of fluorite structure having cubic symmetry with Fm3m space group was analyzed by powder X-ray diffraction patterns. Spherical shaped nanoparticles with clear boundaries were observed by surface morphological studies. Diverse elements Y, Zr, Dy and O were present in the optimized nanophosphors as examined by energy dispersive X-ray analysis. Upon near ultraviolet (NUV) excitation at 354 nm wavelength, the Y2(1-x)Dy2xZr2O7 phosphors displayed the characteristic white light emanation resulted from blue and yellow emission owing to 4F9/2→6H15/2 (450-525 nm) and 4F9/2→6H13/2 (525-650) transitions, respectively. With the doping of 1.5 mol% amount of Dy3+ ions in Y2(1-x)Dy2xZr2O7 powders showed maximum photoluminescence emission, above which intensity was quenched due to dipole-dipole interactions. In addition, Y1.97Dy0.03Zr2O7 nanopowders exhibit CIE colour coordinates (0.2605, 0.3145) residing in white region. The closeness of this value to the white emission coordinates of the National Television System Committee (NTSC) endorsed Y2(1-x)Dy2xZr2O7 nanophosphors as fascinating candidate for displays and white light emitting diodes.

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Ivanov, Artem. "Implementation of Flexible Displays for Smart Textiles Using Processes of Printed Electronics." Additional Conferences (Device Packaging, HiTEC, HiTEN, and CICMT) 2019, NOR (June 1, 2019): 000021–28. http://dx.doi.org/10.4071/2380-4491-2019-nor-ivanov.

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Abstract Utilisation of light emitting diodes (LEDs) and printed electroluminescent elements for manufacturing of flexible displays to be integrated in textile items was analysed. The comparative investigation focused on the necessary manufacturing processes, on the architecture of driver electronics, on achievable display brightness, on lifetime expectations and reliability aspects of the systems. Printed electroluminescent display demonstrators were manufactured and integrated in jackets for the currently running field test. Description of the produced systems as well as the results of the comparative analysis are presented.

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Lipunova, Galina N., Emiliya V. Nosova, Valery N. Charushin, and Oleg N. Chupakhin. "Functionalized Quinazolines and Pyrimidines for Optoelectronic Materials." Current Organic Synthesis 15, no. 6 (August 29, 2018): 793–814. http://dx.doi.org/10.2174/1570179415666180622123434.

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Background: Quinazolines, the important group of benzodiazines, are widely known in medicinal chemistry due to their broad spectrum of biological activities. Notably, extensive research on the synthesis and application of quinazoline derivatives for electronic devices, luminescent elements, photoelectric conversion elements, and image sensors has been published recently. Objective: This review reports luminescent small molecules and chelate compounds including a quinazoline or pyrimidine ring in their scaffold highlighting their applications related to photo- and electroluminescence. Conclusion: It is clear from the review of the topic that the incorporation of quinazoline and pyrimidine fragments into π-extended conjugated systems is of great value for the creation of novel optoelectronic materials. Polyhalogen derivatives represent the major starting materials for polysubstituted fluorescent quinazolines. Electroluminescent properties of aryl(hetaryl)substituted quinazolines with π-extended conjugated systems proved to be the most important. Incorporation of benzimidazole, carbazole, triphenylene or triphenylamine fragments into quinazoline scaffold allows fabricating materials for organic light-emitting diodes, including white OLEDs and highly efficient red phosphorescent organic light-emitting diodes. Moreover, arylvinylsubstituted quinazolines are of great interest as potential structures for nonlinear optical materials and for colorimetric pH sensors. Iridium complexes based on 2-aryl(thienyl) quinazoline or pyrimidine derivatives represent high-efficiency phosphorescent materials for OLEDs. Pyrimidine push-pull systems are of considerable importance as potential photosensitizers for dye-sensitized solar cells. Pyrimidine derivatives bearing phenylacridine or phenylphenoxazine fragments at the positions 4 and 6 are capable to function as thermally activated delayed fluorescence emitters.

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Qaim, Syed M., Bernhard Scholten, Ingo Spahn, and Bernd Neumaier. "Positron-emitting radionuclides for applications, with special emphasis on their production methodologies for medical use." Radiochimica Acta 107, no. 9-11 (September 25, 2019): 1011–26. http://dx.doi.org/10.1515/ract-2019-3154.

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Abstract A survey of the positron-emitting radionuclides over the whole mass range of the Periodic Table of Elements was carried out. As already known, positrons are preferably emitted from light mass neutron deficient radionuclides. Their emission from heavier mass nuclides is rather rare. The applications of positron annihilation in three areas, namely materials research, plant physiology and medical diagnosis, are reported. The methods of production of positron emitters are discussed, with emphasis on radionuclides presently attracting more attention in theranostics and multimodal imaging. Some future perspectives of radionuclide development technologies are considered.

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Neyezhmakov, P., E. Tymofeiev, and О. Lyashenko. "Photometer for Measuring the Characteristics of the Light Source with Directed Light Radiation." Metrology and instruments, no. 4 (August 30, 2018): 27–32. http://dx.doi.org/10.33955/2307-2180(4)2018.27-32.

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The accuracy of the measurement of the main photometric characteristic of the emitter determines the error for determining the total light flux of the light sources, especially light emitting diodes, for which it should not exceed 5 per cent. Existing measurement methods with the use of integrated spheres, goniophotometers and goniophotometers of the near field require a great deal of time and have a great deal of value. To eliminate these shortcomings, a method for measuring the characteristics of light sources with directed light distribution is proposed based on the use of a set of meters located in a plane perpendicular to the main direction of the source radiation propagation. On the basis of this method, a photometer for measuring the characteristics of the directional light sources is developed, which allows to quickly, in real time, determine the characteristics of the emitters. The method of determining the parameters of light distribution of directed sources of light for the construction of its photometric body is not required to use a rotary means. Taking into account the significant influence of temperature fluctuations on the characteristics of LED light sources, it is possible will upgrade the proposed method for determining the photometric body of the radiation source in real time and when the temperature changes due to the introduction of additional elements in the future.

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Jiang, Xiaojie, Zhen Fan, Li Luo, and Lishuang Wang. "Advances and Challenges in Heavy-Metal-Free InP Quantum Dot Light-Emitting Diodes." Micromachines 13, no. 5 (April 30, 2022): 709. http://dx.doi.org/10.3390/mi13050709.

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Light-emitting diodes based on colloidal quantum dots (QLEDs) show a good prospect in commercial application due to their narrow spectral linewidths, wide color range, excellent luminance efficiency, and long operating lifetime. However, the toxicity of heavy-metal elements, such as Cd-based QLEDs or Pb-based perovskite QLEDs, with excellent performance, will inevitably pose a serious threat to people’s health and the environment. Among heavy-metal-free materials, InP quantum dots (QDs) have been paid special attention, because of their wide emission, which can, in principle, be tuned throughout the whole visible and near-infrared range by changing their size, and InP QDs are generally regarded as one of the most promising materials for heavy-metal-free QLEDs for the next generation displays and solid-state lighting. In this review, the great progress of QLEDs, based on the fundamental structure and photophysical properties of InP QDs, is illustrated systematically. In addition, the remarkable achievements of QLEDs, based on their modification of materials, such as ligands exchange of InP QDs, and the optimization of the charge transport layer, are summarized. Finally, an outlook is shown about the challenge faced by QLED, as well as possible pathway to enhancing the device performance. This review provides an overview of the recent developments of InP QLED applications and outlines the challenges for achieving the high-performance devices.

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Wang, Tianlei, Meitang Liu, Hongwen Ma, and Defu Cao. "Synthesis and Characterization of La-Doped Luminescent Multilayer Films." Journal of Chemistry 2017 (2017): 1–6. http://dx.doi.org/10.1155/2017/8203581.

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In this work, we have successfully designed ordered luminescent multilayer films based on La-doped nonmagnetic or magnetic inorganic nanostructure with electronic microenvironment (EM). The inorganic nanosheets with opposite charge can assemble EM between the interlayers. At the same time, their elements on nanosheets of layer double hydroxides (LDHs) are facile to be replaced so that we can introduce transition metal or lanthanide elements. Besides, ferromagnetic effect (FE) can be formed in this microenvironment due to introducing transition metal on LDHs nanosheets. As a result, we confirm that EM, FE, and doping La element in the LDHs can affect the vibration of backbone of chromophores and then prolong the luminescent lifetime, which suggests a new pathway for developing the novel light-emitting thin films.

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Kopsell, Dean A., and Carl E. Sams. "Increases in Shoot Tissue Pigments, Glucosinolates, and Mineral Elements in Sprouting Broccoli after Exposure to Short-duration Blue Light from Light Emitting Diodes." Journal of the American Society for Horticultural Science 138, no. 1 (January 2013): 31–37. http://dx.doi.org/10.21273/jashs.138.1.31.

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Microgreens are specialty leafy crops harvested just above the roots after the first true leaves have emerged and are consumed fresh. Broccoli (Brassica oleacea var. italica) microgreens can accumulate significant concentrations of cancer-fighting glucosinolates as well as being a rich source of other antioxidant phytochemicals. Light-emitting diodes (LEDs) now provide the ability to measure impacts of narrow-band wavelengths of light on seedling physiology. The carotenoid zeaxanthin has been hypothesized to be a blue light receptor in plant physiology. The objective of this study was to measure the impact of short-duration blue light on phytochemical compounds, which impart the nutritional quality of sprouting broccoli microgreens. Broccoli microgreens were grown in a controlled environment under LEDs using growing pads. Seeds were cultured on the pads submerged in deionized water and grown under a 24-hour photoperiod using red (627 nm)/blue (470 nm) LEDs (350 μmol·m−2·s−1) at an air temperature of 23 °C. On emergence of the first true leaf, a complete nutrient solution with 42 mg·L−1 of nitrogen (N) was used to submerge the growing pads. At 13 days after sowing, broccoli plantlets were grown under either: 1) red and blue LED light (350 μmol·m−2·s−1); or 2) blue LED light (41 μmol·m−2·s−1) treatments for 5 days before harvest. The experiment was repeated three times. Frozen shoot tissues were freeze-dried and measured for carotenoids, chlorophylls, glucosinolates, and mineral elements. Comparing the two LED light treatments revealed the short-duration blue LED treatment before harvest significantly increased shoot tissue β-carotene (P ≤ 0.05), violaxanthin (P ≤ 0.01), total xanthophyll cycle pigments (P ≤ 0.05), glucoraphanin (P ≤ 0.05), epiprogoitrin (P ≤ 0.05), aliphatic glucosinolates (P ≤ 0.05), essential micronutrients of copper (Cu) (P = 0.02), iron (Fe) (P ≤ 0.01), boron (B), manganese (Mn), molybdenum (Mo), sodium (Na), zinc (Zn) (P ≤ 0.001), and the essential macronutrients of calcium (Ca), phosphorus (P), potassium (K), magnesium (Mg), and sulfur (S) (P ≤ 0.001). Results demonstrate management of LED lighting technology through preharvest, short-duration blue light acted to increase important phytochemical compounds influencing the nutritional value of broccoli microgreens.

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