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Chinese Physics B 2019年第5期28卷 361-365页

作者：李光王林媛宋伟东姜健罗幸君郭佳琦贺龙飞张康吴启保李述体 Guangdong Engineering Research Center of Optoelectronic Functional Materials and Devices Institute of Opto-Electronic Materials and Technology South China Normal University Guangdong Institute of Semiconductor Industrial Technology Guangdong Academy of Sciences School of Intelligent Manufacture and Equipment Shenzhen Institute of Information Technology

The conventional stationary Al content Al GaN electron blocking layer(EBL) in ultraviolet light-emitting diode(UV LED) is optimized by employing a linearly graded Al Ga N inserting layer which is 2.0 nm Al_(0.3) Ga_(0.7) N/5.0 nm Alx Ga_(1-x) N/8.0 nm Al_(0.3) Ga_(0.7) N with decreasing value of x. The results indicate that the internal quantum efficiency is significantly improved and the efficiency droop is mitigated by using the proposed structure. These improvements are attributed to the increase of the effective barrier height for electrons and the reduction of the effective barrier height for holes,which result in an increased hole injection efficiency and a decreased electron leakage into the p-type region. In addition,the linearly graded AlGaN inserting layer can generate more holes in EBL due to the polarization-induced hole doping and a tunneling effect probably occurs to enhance the hole transportation to the active regions, which will be beneficial to the radiative recombination.

关键词： ultraviolet light-emitting diode electron blocking layer internal quantum efficiency

Dependence of limited radiative recombination rate of InGaN-based light-emitting diode on lattice temperature with high injection

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Chinese Physics B 2020年第4期29卷 488-493页

作者：高江东张建立全知觉刘军林江风益 National Institute of LED on Silicon Substrate Nanchang UniversityNanchang 330096China

It is observed that the radiative recombination rate in InGaN-based light-emitting diode decreases with lattice temperature *** effect of lattice temperature on the radiative recombination rate tends to be stable at high ***,there should be an upper limit for the radiative recombination rate in the quantum well with the carrier concentration increasing,even under the same lattice temperature.A modified and easily used ABC-model is *** describes that the slope of the radiative recombination rate gradually decreases to zero,and further reaches a negative value in a small range of lattice temperature *** provide a new insight into understanding the dependence of the radiative recombination rate on lattice temperature and carrier concentration in InGaN-based light-emitting diode.

关键词： InGaN-based light-emitting diode carrier recombination ABC-model lattice temperature

The strategies for preparing blue perovskite light-emitting diodes

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Journal of Semiconductors 2020年第5期41卷 26-33页

作者： Jianxun Lu Zhanhua Wei Institute of Luminescent Materials and Information Displays College of Materials Science and EngineeringHuaqiao UniversityXiamen 361021China

Metal halide perovskites have attracted tremendous interest due to their excellent optical and electrical properties,and they find many promising applications in the optoelectronic fields of solar cells,light-emitting diodes,and *** to the contributions of international researchers,significant progress has been made for perovskite light-emitting diodes(Pero-LEDs).The external quantum efficiencies(EQEs)of Pero-LEDs with emission of green,red,and near-infrared have all exceeded 20%.However,the blue Pero-LEDs still lag due to the poor film quality and deficient device ***,we summarize the strategies for preparing blue-emitting perovskites and categorize them into two:compositional engineering and size controlling of the emitting *** advantages and disadvantages of both strategies are discussed,and a perspective of preparing high-performance blue-emitting perovskite is *** challenges and future directions of blue PeroLEDs fabrication are also discussed.

关键词： perovskite blue light-emitting diodes

Giant efficiency and color purity enhancement in multicolor inorganic perovskite light-emitting diodes via heating-assisted vacuum deposition

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Journal of Semiconductors 2020年第5期41卷 91-98页

作者： Boning Han Qingsong Shan Fengjuan Zhang Jizhong Song Haibo Zeng School of Materials Science and Engineering Nanjing University of Science and TechnologyNanjing 210094China MIIT Key Laboratory of Advanced Display Materials and Devices Institute of Optoelectronics&NanomaterialsNanjing 210094China School of Physics and Engineering Zhengzhou UniversityZhengzhou 450052China

Inorganic perovskites(Cs Pb X3(X=I,Br,Cl))have broad prospection in the field of high-definition displaying due to its excellent optoelectronic *** vacuum deposition process possesses advantages and competitiveness in the industrialized ***,the performance of light emitting diodes(LEDs)based on vacuum-deposited is incredibly ***,we proposed a heating-assisted vacuum deposition(HAVD)method to construct inorganic perovskite LEDs(Pe LEDs)with enhanced *** roughness and crystallinity of perovskite film were improved by regulating the heating treatment of *** the perovskite film exhibited largely rise in luminescence,with decreasing defect ***,with the optimized temperature,the green Pe LEDs exhibited 100-fold improvement of external quantum efficiency(EQE)with the luminance of up to 11941 cd/m2,and the full width at half-maximum(FWHM)of the electroluminescence(EL)spectra was decreased from 25 to 17 *** the same time,the red and blue Pe LEDs also exhibited obvious enhancement in EQE and luminance by HAVD method,and both the FWHM of EL spectra dropped below 20 nm,exhibiting excellent high color *** strategy has a huge potential to be a new commonly used method for low-cost fabrication of displays and lighting.

关键词： all-inorganic perovskites light-emitting diodes heating assisted vacuum deposition Cs Pb Br3 color purity

Color-Tunable Hybrid White Organic light-emitting Diodes with Double Interlayers

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Optics and Photonics Journal 2017年第8期7卷 99-105页

作者： Chunhong Gao Ziyang Xiong Fuxing Yu Xingjuan Ma Yue Zhang Xin Zeng Zuhong Xiong School of Physical Science and Technology MOE Key Laboratory on Luminescence and Real-Time Analysis Southwest University Chongqing China

An efficient color-tunable hybrid white organic light-emitting diode is demonstrated with double interlayers of 2,7-bis(carbazol-9-yl)-9,9-ditoylfluo- rene/2-(diphenylphosphoryl) spiroflu-orene (DMFL-CBP/SPPO1) inserted between blue fluorescent and yellow phosphorescent-emitting layers, and exhibits Commission Internationale de l’Eclairage (CIE1931) ranging from warm white (0.4368, 0.4497) to cool white (0.2781, 0.2896) with driving current density from 0.2 to 40 mA/cm2. The recombination of singlet and the triplet excitons in blue fluores-cent-emitting layer and yellow phosphorescent-emitting layer, respectively, can be modulated by both the thickness of these double interlayers and the applied current densities.

关键词： Hybrid White Organic light-emitting Diode Color-Tunable Singlet Exciton Triplet Exciton Phosphor

Hole-Buffer Material Derived from Pyrene, Schiff Base and Tris to Enhance Emission Efficiency of Polymer light-emitting Diodes

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Journal of Materials Science and Chemical Engineering 2018年第3期6卷 31-46页

作者： Jyun-Huei Liou Ping-Feng Hsu Yun Chen Department of Chemical Engineering National Cheng Kung University Taiwan

Inserting a hole-buffer layer is an effective way to enhance emission efficiency of electroluminescence devices. We have successfully synthesized a new hole-buffer material PSB composed of pyrene, Schiff base and trihydroxy tert-butyl groups by the Suzuki-coupling reaction. The HOMO and LUMO lev-els were -6.33 eV and -2.55 eV, respectively, as estimated from cyclic volt-ammograms. In addition, homogeneous films (rms roughness ~2 nm) were readily obtained by spin-coating process. Multilayer polymer light-emitting diodes, ITO/PEDOT:PSS/PSB/SY/LiF/Al, have been fabricated using PSB as hole-buffer layer (HBL). Inserting PSB as HBL significantly enhances the per-formance (maximum luminance: 26,439 cd/m2, maximum current efficiency: 7.03 cd/A), compared with the one without PSB (9802 cd/m2, 2.43 cd/A). It is also superior to the device with conventional BCP as hole-blocking layer (ITO/PEDOT:PSS/SY/BCP/LiF/Al: 15,496 cd/m2, 5.56 cd/A). Current results strongly indicate that the PSB is a potential hole-buffer material for electrolu-minescent devices.

关键词： Hole-Buffer Polymer light-emitting Diodes Pyrene Schiff Base Spin-Coating

Enhancement in light Extraction Efficiency of GaN-Based light-emitting Diodes Using Double Dielectric Surface Passivation

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Optics and Photonics Journal 2012年第3期2卷 185-192页

作者： Chung-Mo Yang Dong-Seok Kim Yun Soo Park Jae-Hoon Lee Yong Soo Lee Jung-Hee Lee GaN Power Research Group R&D Institute Samsung LED Co. Ltd Suwon Republic of Korea School of Electrical Engineering and Computer Science Kyungpook National University Daegu Republic of Korea

SiO2Al2O3 double dielectric stack layer was deposited on the surface of the GaN-based light-emitting diode (LED). The double dielectric stack layer enhances both the electrical characteristics and the optical output power of the LED because the first Al2O3 layer plays a role of effectively passivating the p-GaN surface and the second lower index SiO2 layer increases the critical angle of the light emitted from the LED surface. In addition, the effect of the Fresnel reflection is also responsible for the enhancement in output power of the double dielectric passivated LED. The leakage current of the LED passivated with Al2O3 layer was -3.46 × 10-11 A at -5 V, at least two and three orders lower in magnitude compared to that passivated with SiO2 layer (-7.14 × 10-9 A) and that of non-passivated LED (-1.9 × 10-8 A), respectively, which indicates that the Al2O3 layer is very effective in passivating the exposed GaN surface after dry etch and hence reduces nonradiative recombination as well as reabsorption of the emitted light near the etched surface.

关键词： GaN light-emitting Diode (LED) Al2O3 PEALD Passivation Double Dielectric Stack Layer

Solution Processable Material Derived from Aromatic Triazole, Azomethine and Tris: Preparation and Hole-Buffering Application in Polymer light-emitting Diodes

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Journal of Materials Science and Chemical Engineering 2018年第9期6卷 6-28页

作者： Chih-Yang Lin Yun Chen Department of Chemical Engineering National Cheng Kung University Taiwan

This work presents the synthesis of a new hole-buffering material TAZS and its successful application in polymer light-emitting diodes to enhance device performance. The TAZS is composed of aromatic 1,2,4-triazolylcore linked with three trihydroxy tert-butyl terminals via azomethine linkages. The TAZS forms ashomogeneous film deposited by spin-coating process. The HOMO and LUMO levels of TAZS are -5.23 eV and -2.40 eV, respectively, as estimated from cyclic voltammogram. The current density results of hole-only and electron-only devices confirm strong hole-buffering capability of TAZS layer. Multilayer PLEDs with different thickness of TAZS (ITO/PEDOT: PSS/TAZS (x nm)/SY/ETL/LiF/Al) have been successfully fabricated, using spin-coating process to deposit hole-injecting PEDOT: PSS, TAZS, and emissive SY layers. The PLED with 16 nm TAZS reveals the optimal device performance, with maximum luminance and maximum current efficiency of 19,046 cd/m2 and 4.08 cd/A, respectively, surpassing those without TAZS as HBL (8484 cd/m2, 2.13 cd/A). The hole-buffering characteristic of TAZS contributes greatly to improved charges’ recombination ratio and enhanced emission efficiency.

关键词： Hole-Buffering Azomethine Aromatic Triazole Tris Polymer light-emitting Diodes Spin-Coating

Effect of Pixellization on Efficiency and Stability of MEH-PPV Based Polymer light-emitting Diodes

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Journal of Encapsulation and Adsorption Sciences 2012年第1期2卷 11-14页

作者： Ranbir Singh Monica Katiyar Department of Materials and Metallurgical Engineering Indian Institute of Technology Kanpur India Samtel Centre for Display Technologies Indian Institute of Technology Kanpur India

Organic light-emitting diodes are generally depicted as sequential deposition of active layers and electrodes onto a substrate, but commercial devices are fabricated using pixellization technique, where an insulator layer is introduced between the indium tin oxide and organic layer to define the area of the active device. Here, we have inserted a layer of photoresist (thickness ~ 200 nm) at the edge of patterned anode (indium tin oxide) and between the anode and hole transport layer (Poly 3, 4-ethylenedioxythiophene poly styrenesulfonate) to examine its effect on the leakage current of organic light-emitting diode and on the electron-hole recombination ratio in the emission area, as a result increasing the luminance efficiency. Current leakage causes the loss of charges, which adversely affects the recombination of electrons and holes in the emitting zone and results in poorer luminance efficiency. In this paper, we report the effect of pixellization on current density-voltage, luminescence-voltage and degradation behavior of single layer Poly[2-methoxy-5-(2’-ethylhexyloxy)-1, phenylene vinylene] based organic light-emitting diodes. Devices with isolation layer have 30% higher external electroluminescence quantum efficiency and reduced device degradation in comparison to without isolation layer.

关键词： Organic light-emitting Diodes Pixellization Isolation Layer Electroluminescence Quantum Efficiency

Synthesis and Characterization of Poly(1-methoxy-4-octyloxy)-Para-Phenylene Vinylen for light-emitting Diodes Application

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Advances in Materials Physics and Chemistry 2012年第4期2卷 38-39页

作者： Piched Anuragudom Department of Chemistry Faculty of Liberal Arts and Science Kasetsart University Kamphaeng Nakhon Pathom 73140 Thailand

In this study, the conjugated polymer, poly(1-methoxy-4-octyloxy)-para-phenylene vinylene (MO-p-PPV) was synthesized and characterized. MO-p-PPV was synthesized according to Gilch polymerization mechanism by using 4-methoxyphenol as starting material in the presence of potassium tert-butoxide (1M in THF). The product was further purified by multiple precipitations in different solvents such as methanol, tetrahydrofuran, isopropyl alcohol and hexane. The final product was dried to afford MO-p-PPV as a red solid. The resulting polymer was completely soluble in common organic solvents. The structure of monomer and optical properties of polymer were characterized by proton nuclear magnetic resonance (1H-NMR) spectroscopy, UV-vis spectroscopy, and fluorescence spectroscopy. The UV-vis spectrum showed absorption maxima for MO-p-PPV at 491 nm. Similarly, fluorescence spectrum showed λmax emission at 540 nm.

关键词： Component Poly(1-Methoxy-4-Octyloxy)-Para-Phenylene Vinylen Gilch Polymerization light-emitting Diodes