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A New Conducting Polymer Electrode for Organic Electroluminescence devices

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Chinese Physics Letters 2008年第8期25卷 3052-3055页

作者：瞿述彭景翠 School of Physics and Microelectronic Hunan University Changsha 410082 Department of Physics and Electronic Information Hunan Institute of Science and Technology Yueyang 414006

Conducting polymer polydimethylsiloxane （PDMS） is studied for the high performance electrode of organic electroluminescence devices. A method to prepare the electrode consisting of a SiC thin film and PDMS is investigated. By using ultra thin SiC films with different thicknesses, the organic electroluminescence devices are obtained in an ultra vacuum system with the model device PDMS/SiC/PPV/Alq3, where PPV is poly para-phenylene vinylene and Alq3 is tris（S-hydroxyquinoline） aluminium. The capacitance voltage （C - V）, capacitance-frequency （C - F）, current-voltage （I - V）, radiation intensity-voltage （R - V） and luminance eFficiency-voltage （E - V） measurements are systematically studied to investigate the conductivity, Fermi alignment and devices properties in organic semiconductors. Scanning Kelvin probe measurement shows that the work function of PDMS/SiC anode with a 2.5-nm SiC over layer can be increased by as much as 0.28eV, compared to the conventional ITO anode. The result is attributed to the charge transfer effect and ohmic contacts at the interface.

关键词： light-emitting devices QUANTUM EFFICIENCY INTERFACES ALIGNMENT CATHODE DIPOLE DIODES LEVEL FILMS METAL

Micro-light-emitting-diode array with dual functions of visible light communication and illumination

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Chinese Physics B 2017年第10期26卷 490-495页

作者：黄涌郭志友孙慧卿黄鸿勇 Guangdong Provincial Key Laboratory of Nanophotonic Functional Materials and devices Institute of the Opto-Electronic Materials and Technology South China Normal University Guangdong Engineering Technology Research Center of Optoelectronic Functional Materials and devices

We demonstrate high-speed blue 4 ×4 micro-light-emitting-diode （LED） arrays with 14 light-emitting units （two light-emitting units are used as the positive and negative electrodes for power supply, respectively） comprising multiple quantum wells formed of GaN epitaxial layers grown on a sapphire substrate, and experimentally test their applicability for being used as VLC transmitters and illuminations. The micro-LED arrays provide a maximum -3-dB frequency response of 60.5 MHz with a smooth frequency curve from 1 MHz to 500 MHz for an optical output power of 165 mW at an injection current of 30 mA, which, to our knowledge, is the highest response frequency ever reported for blue GaN-based LEDs operating at that level of optical output power. The relationship between the frequency and size of the device single pixel diameter reveals the relationship between the response frequency and diffusion capacitance of the device.

关键词： light-emitting devices optical communications diffusion capacitance

Multicolor carbon dots with concentration-tunable fluorescence and solvent-affected aggregation states for white light-emitting diodes

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Nano Research 2020年第1期13卷 52-60页

作者： Fanyong Yan Yingxia Jiang Xiaodong Sun Junfu Wei Liang Chen Yuyang Zhang State Key Laboratory of Separation Membranes and Membrane Processes School of Chemistry and Chemical EngineeringTiangong UniversityTianjin300387China Graduate School of Life Science Hokkaido UniversitySapporo0010024Japan

Multicolor emissive carbon dots(M-CDs)have tremendous potential applications in manifold fields of bioimaging,biomedicine and light-emitting *** now,it is still difficult to produce fluorescence tunable CDs with high quantum yield across the entire visible *** this work,a type of M-CDs with concentration-tunable fluorescence and solvent-affected aggregation states was synthesized by solvothermal treatment of citric acid(CA)and 1-(2-pyridylazo)-2-naphthol(PAN)and the formation mechanism was monitored by different reaction time and raw material *** fluorescence spectra of M-CDs in organic solvents can range from 350 to 750 nm by adjusting the concentration.M-CDs possess different aggregation states in water and organic solvents,accompanied by different fluorescence emission,which is attributed to the different surface states of various component CDs in ***,the obtained products can be uniformly dispersed into polymethylmethacrylate(PMMA)solutions as well as epoxy resins to fabricate transparent CDs/PMMA films and CDs/epoxy composites,which can effectively prevent the aggregation and produce multicolor and white light-emitting diodes(WLED).In addition,the prepared WLED with Commission Internationale de L’Eclairage(CIE)of(0.29,0.31)by using M-CDs/epoxy resin as packages,demonstrating the M-CDs exhibit potential applications for light-emitting devices.

关键词： carbon dots formation mechanism concentration-tunable fluorescence solvent-affected aggregation states light-emitting devices

Ultraviolet emissions realized in ZnO via an avalanche multiplication process

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Chinese Physics B 2013年第7期22卷 41-44页

作者：于吉单崇新申赫张祥伟王双鹏申德振 State Key Laboratory of Luminescence and Applications Changchun Institute of OpticsFine Mechanics and PhysicsChinese Academy of Sciences University of Chinese Academy of Sciences

Au/MgO/ZnO/MgO/Au structures have been designed and constructed in this study. Under a bias voltage, a carrier avalanche multiplication will occur via an impact ionization process in the MgO layer. The generated holes will be drifted into the ZnO layer, and recombine radiatively with the electrons in the ZnO layer. Thus obvious emissions at around 387 nm coming from the near-band-edge emission of ZnO will be observed. The reported results demonstrate the ultraviolet （UV） emission realized via a carrier multiplication process, and so may provide an alternative route to efficient UV emissions by bypassing the challenging p-type doping issue of ZnO.

关键词： avalanche multiplication wide bandgap semiconductor light-emitting devices

Enhancing light extraction of GaN-based blue light-emitting diodes by a tuned nanopillar array

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Chinese Physics B 2014年第1期23卷 500-504页

作者：陈湛旭任远肖国辉李俊韬陈夏王雪华金崇君张佰君 State Key Laboratory of Optoelectronic Materials and Technologies School of Physics and Engineering Sun Y'at-sen University Guangzhou 510275 China School of Electronic and Information Guangdong Polytechnic Normal University Guangzhou 510665 China

Surface patterning of p-GaN to improve the light extraction efficiency of GaN-based blue light-emitting diodes(LEDs) has been investigated. Periodic nanopillar arrays on p-GaN have been fabricated by polystyrene(PS) nanosphere lithography; the diameter of the nanopillars can be tuned to optimize the electrical and optical properties of the LEDs. The electroluminescence intensity of the nanopillar-patterned LEDs is better than that of conventional LEDs; the greatest enhancement increased the intensity by a factor of 1.41 at a 20 mA injection current. The enhancements can be explained by a model of bilayer film on a GaN substrate. This method may serve as a practical approach to improve the efficiency of light extraction from LEDs.

关键词： light-emitting devices nanosphere lithography electroluminescence extraction efficiency

Enhanced light emission from InGaN/GaN quantum wells by using surface plasmonic resonances of silver nanoparticle array

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Chinese Physics B 2014年第12期23卷 559-563页

作者：陈湛旭万巍张佰君何影记金崇君 School of Electronic and Information Guangdong Polytechnic Normal University State Key Laboratory of Optoelectronic Materials and Technologies School of Physics and Engineering Sun Yat-Sen University

The effect of silver nanostructures prepared by nanosphere lithography on the photoluminescence（PL） properties of blue-emitting In Ga N/Ga N quantum wells（QWs） is studied. Arrays of silver nanoparticles are fabricated to yield a collective surface plasmonic resonance（SPR） near to the QWs emission wavelength. A large enhancement in peak PL intensity is observed, when the induced SPR wavelength of the nanoparticles on the QWs sample matches the QWs emission wavelength. The study proves that the SPRs could enhance the light emission efficiency of semiconductor material.

关键词： light-emitting devices photoluminescence metallic nanoparticle nanosphere lithography

Electromechanical Fields and Their Influence on the Internal Quantum Efficiency of GaN-Based light-emitting Diodes

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Acta Mechanica Solida Sinica 2018年第3期31卷 383-390页

作者： Muhammad Usman Kiran Saba Adnan Jahangir Muhammad Kamran Nazeer Muhammad Department of Engineering Sciences Ghulam Ishaq Khan Institute of Engineering Sciences and Technology Swabi 23460 Pakistan Department of Mathematics COMSATS Institute of Information Technology Wah Cantt 47040 Pakistan Department of Electrical Engineering COMSATS Institute of Information Technology Wah Cantt 47040 Pakistan

The effect ofelectromechanical fields, i.e., polarization fields, on the efficiency droop of GaN-based light-emitting diodes is presented using both experimental and numerical analyses. The role of incorporating such polarization charge density in device performance is numerically investigated and further compared with the experimental results of internal quantum efficiency of three different devices in consideration.

关键词： Optoelectronic devices Photonic bandgap materials Visible and ultraviolet sources light-emitting devices

Optimization of a poly (p-phenylene benzobisoxazole)-based light-emitting device with a complex cathode structure

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Chinese Physics B 2013年第11期22卷 607-611页

作者：张晓晋何志群汪璟穆林平赵瓛梁春军庄启昕韩哲文 Key Laboratory of Luminescence and Optical Information Ministry of Education Institute of Optoelectronic TechnologyBeijing Jiaotong University Key Laboratory for Specially Functional Polymeric Materials and Related Technology Ministry of Education East China University of Science and Technology

In this work, we report the preparation of a series of electroluminescent （EL） devices based on a high-performance polymer, poly（p-phenylene benzobisoxazole）（PBO）, and their optoelectronic properties, which have been rarely explored. The device structure is optimised using a complex cathode structure of tris-（8-hydoxyquinoline） aluminium （Alq3）/LiF/Al. By tuning the thickness of the Alq3 layer, we improve the device efficiency dramatically in an optimized condition. Further analysis reveals that the Alq3 layer in the complex cathode structure acts as a hole blocker in addition to its electron-injection role. A green light emission with a maximum brightness of 8.7×103 cd/m2 and a moderate current efficiency of 4.8 cd/A is obtained. These values are the highest ever reported for PBO devices. The high operational stability demonstrated by the present device makes it a promising tool for display and lighting applications. A new material is added to the selection of polymers used in this field up to now.

关键词： electroluminescence organic semiconductors light-emitting devices electronic transport phe-nomena

Pure RGB Emissions Based on a White OLED Combined with Optical Colour Filters

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Chinese Physics Letters 2006年第4期23卷 1012-1014页

作者：吴晓明华玉林王肇圻印寿根郑加金邓家春 M.C.Petty Institute of Material Physics Tianjin University of Technology Tianjin 300191 Institute of Modern Optics Nankai University Tianjin 300071 Centre for Molecular and Nanoscale Electronics University of Durham Durham DH1 3LE UK

We report on a white organic light emitting device （OLED） with a single light emitting layer consisting of a greenish-white emitting host bis-（2-（2-hydroxyphenyl） benzothiazole）zinc （Zn（BTZ）2 ） and an orange-red dopant 5,6,11,12-tetraphenylnaphthacene （rubrene）. The Commission Internationale De L＇Eclairage （CIE） coordinates, external quantum efficiency, and brightness of the white OLED are （0.341, 0.334）, 0.63% and 4000 Cd/m^2 at the bias of 20 V, respectively. Pure red-green-blue （RGB） emissions have been successfully achieved from the white OLED combined well with several built-in optical colour filters （CFs）. The CIE coordinates of the white mixture calculated in theory are very close to the coordinates of the white mixture which recorded with spectrophotometer in practice.

关键词： light-emitting devices DISPLAYS