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[IEEE 2019 20th International Conference on Solid-State Sensors, Actuators and Microsystems & Eurosensors XXXIII (TRANSDUCERS & EUROSENSORS XXXIII) - Berlin, Germany (2019.6.23-2019.6.27)] 2019 20th International Conference on Solid-State Sensors, Actuators and Microsystems & Eurosensors XXXIII (TRANSDUCERS & EUROSENSORS XXXIII) - High-Color-Purity Microfluidic Quantum Dots Light-Emitting Diodes Using the Electroluminescence of the Liquid Organic Semiconductor Backlight
摘要： We proposed microfluidic quantum dots light-emitting diodes using a liquid organic semiconductor (LOS) and quantum dots (QDs) solutions. LOS and QDs solutions were used as a backlight and a luminophore, respectively. Channels for the QDs solutions were stacked on the LOS backlight. With applying voltage, red photoluminescence (PL) emissions of the QDs solution excited by the LOS backlight, was observed. The full width at half maximum of the red-PL emission was 29.8 nm, which is narrower than that of the LOS backlight by 40%. The proposed device is expected to provide highly-bright flexible displays with high-color-purity.
关键词： liquid organic semiconductor (LOS),Liquid organic light-emitting diodes (OLEDs),high-color-purity,functional organic liquid,quantum dots light-emitting diodes (QLEDs)
更新于2025-09-11 14:15:04
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[IEEE 2019 IEEE Energy Conversion Congress and Exposition (ECCE) - Baltimore, MD, USA (2019.9.29-2019.10.3)] 2019 IEEE Energy Conversion Congress and Exposition (ECCE) - An Energy Efficient Li-Fi Transmitter with Single Inductor Multiple Output LED Driver
摘要： High-Efficiency Light-Fidelity (Li-Fi) transmitter for simultaneous illumination and Visible Light Communications (VLC) using LED lighting is presented in this work. The proposed transmitter is based on Single Inductor Multiple Output (SIMO) buck converter with two independently controllable outputs or channels, namely lighting channel and communications channel for enabling flicker free illumination without affecting high-speed modulation of LEDs. By this approach, power converter switching frequency is decoupled from modulation frequency of LEDs, thereby optimizing SIMO converter switching frequency for efficiency and the VLC modulator frequency for high speed data transfers. GaN devices are used to realize VLC modulator for high speed modulation to further enhance the efficiency. Light output with high Color Rendering Index (CRI) is achieved by controlling white LEDs as primary illumination source at lighting channel and red color LEDs at communication channel. Simulations and experimental results to validate the proposed transmitter are presented.
关键词： Single Inductor Multiple Output Converters,Color Rendering Index(CRI),Light-Fidelity(Li-Fi),High Brightness Light Emitting Diodes(HB-LED),Visible Light Communications (VLC),IoT (Internet of Things)
更新于2025-09-11 14:15:04
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Influence of the Silver Nanocrystal Shape on the Luminous Efficiency of Blue-Emitting Polymer Light-Emitting Diodes
摘要： Truncated silver nanodecahedrons (TAgNDs) and truncated silver nanoplates (TAgNPs) fabricated via chemical reduction and photochemical methods were added to poly[3,4-ethylenedioxythiophene]:poly[styrenesulfonate] (PEDOT:PSS) as a dopant to promote the luminous efficiency of blue-emitting polymer light-emitting diodes (PLEDs). The differences in shape between TAgNDs and TAgNPs result in better dispersion of TAgNDs in PEDOT:PSS. Therefore, at an optimal doping concentration (the distributed density in the light-emitting region is 6.88 μg cm?2 for TAgNDs and 5.16 μg cm?2 for TAgNPs), the average current efficacy and maximum electroluminescence intensity enhancement factor for TAgNDs-doped PLED were 4.18 cd A?1 and 420% respectively, which are much higher than those for TAgNPs-doped PLED (1.83 cd A?1 and 200%) at a luminescence wavelength of 440 nm.
关键词： truncated silver nanoplates,blue-emitting polymer light-emitting diodes,luminous efficiency,truncated silver nanodecahedrons
更新于2025-09-11 14:15:04
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Highly-Conductive, Transparent Ga-Doped ZnO Nanoneedles for Improving the Efficiencies of GaN Light-Emitting Diode and Si Solar Cell
摘要： The growths of transparent, highly-conductive Ga-doped ZnO (GaZnO) nanoneedles (NNs) on the tops of GaN-based light-emitting diodes (LEDs) and Si solar cells for enhancing light extraction and reducing surface reflection, respectively, and hence increasing their efficiencies are demonstrated. The GaZnO NNs are grown based on the vapor-liquid-solid process by using surface Ag nanoparticles (NPs) as growth catalyst. In the application to LED, the residual Ag NPs can induce the surface plasmon (SP) coupling effect for increasing the LED emission efficiency. By combining the SP coupling effect, the light extraction effects of the GaZnO NNs and simultaneously deposited GaZnO thin film, and the current spreading effect of the thin film, the LED output intensity can be increased by 100%. In the solar cell application, the SP resonance of the residual Ag NPs can also enhance sunlight harvest and hence the energy conversion efficiency. By combining the effects of the residual Ag NPs, the GaZnO thin film, and the GaZnO NNs, the energy conversion efficiency of a Si solar cell can increase from 9.65 to 12.30%, corresponding to a relative enhancement of 27.5%.
关键词： Ga-doped ZnO,light extraction,light-emitting diodes,solar cells,surface plasmon,anti-reflection,nanoneedles
更新于2025-09-11 14:15:04
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Facile approaches to prepare n-ZnO/(i-ZnO)/p-GaN heterojunction light-emitting diodes with white-light-electroluminescence
摘要： White-light-emitting diode (LED) with effective energy conservation and long service life could be employed in numerous applications. In this study, the high-performance n-ZnO films were first prepared via pulsed laser deposition on p-GaN substrates and then the n-ZnO/p-GaN heterojunction LED was fabricated. This LED exhibits blue and yellow light emission, and their emission intensities can be tuned by adjustment of the fabrication parameters (e.g. oxygen pressure) and/or by introduction of a semi-insulating i-ZnO layer to form a p-GaN/i-ZnO/n-ZnO heterojunction. Thus, a facile approach has been proposed for the preparation of white LED.
关键词： n-ZnO,white-light-electroluminescence,heterojunction,p-GaN,light-emitting diodes
更新于2025-09-11 14:15:04
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Self-Catalytic-Grown SnOx Nanocones for Light Outcoupling Enhancement in Organic Light-Emitting Diodes
摘要： Light extraction in organic light-emitting diodes (OLEDs) was improved by applying SnOx nanocones grown via thermal annealing in a low-O2 atmosphere. SnOx was easily fabricated through thermal processing after Sn deposition. The diameter of the SnOx nanocones was controlled by changing the deposition thickness of Sn. The SnOx nanocones induced strong Mie scattering, which reduced the total internal reflection in the glass substrate. Consequently, the OLED with SnOx nanocones exhibited a 23% increase in the external quantum efficiency compared with a reference device.
关键词： Mie scattering,SnOx nanostructure,light extraction,organic light-emitting diodes (OLEDs),FDTD simulation
更新于2025-09-11 14:15:04
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Recent progress on exciplex-emitting OLEDs
摘要： The thermally-activated-delayed-fluorescence (TADF) characteristics makes exciplexes being the hot subject in the organic light-emitting diode (OLED) research field. The theoretical limit for the efficiency of the conventional fluorescent OLEDs have been leaped by exploiting the triplet harvesting ability of exciplexes. Exciplexes are easily formed by blending electron donor molecules and electron acceptor molecules, which are generally hole transporting materials and electron transporting materials, respectively, resulting in easy access for employing exciplexes to OLEDs. We introduce the photo-physical characteristics of exciplexes derived from the charge-transfer characteristics and their application to OLEDs as emitters. Single exciplex-emitting OLEDs as well as exciplex emission-based white OLEDs are covered in this review.
关键词： organic light-emitting diodes,Exciplexes,thermally activated delayed fluorescence
更新于2025-09-11 14:15:04
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12.1: <i>Invited Paper:</i> Polarization control and optical efficiency improvement of light emitted from OLED using liquid crystalline luminophores
摘要： Highly circularly polarized (CP) light is generated by using a twisted conjugated polymer structure with a small amount of chiral molecules as the light emitting layer of the OLED. It is confirmed that the luminous efficiency is increased by 60% compared to the conventional OLED structure.
关键词： organic light emitting diodes,conjugated polymer,polarized emission,chiral dopant,Circular polarization
更新于2025-09-11 14:15:04
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P‐9.6: Highly Luminescent Blue Quantum Dots Light‐Emitting Diodes
摘要： A better charge balance is realized for blue quantum dot light-emitting diodes (QLEDs) through doping the charge transport layer (CTL) to improve hole injection and suppress redundant electrons. High performance blue QLEDs were achieved by fine-tuning the charge balance within the emitting layer.
关键词： electron-transporting layer,quantum dots light-emitting diodes,charge balance,hole-transporting layer,hybrid charge transporting layer
更新于2025-09-11 14:15:04
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Regulation of Singlet and Triplet Excitons in a Single Emission Layer: Efficient Fluorescent/Phosphorescent Hybrid White Organic Light-Emitting Diodes
摘要： Two e?cient ?uorescent molecules, viz., (E)-2-(2-4-(1-2,3-dihydrobenzo[b][1,4]dioxin-5-yl)-4,5-diphenyl-H-imidazole-2-yl)-[1,1-biphenyl]-4-yl)vinyl-1-yl-(naphthalene-1-yl)-1H-phenanthro[9,10-d]imidazole (DDIBNPPI) and (E)-4-(2-(2-(-4′-1(2,3-dihyderobenzo[b][1,4]dioxin-5-yl)-4,5-diphenyl-1H-imidazole-2-yl)-[1,1′-biphenyl]-4-yl)vinyl)-1H-phenanthr[9,10-d]imidazole-1-yl)-1-napthronitrile (DDIBPPIN), were designed and synthesized. DDIBNPPI and DDIBPPIN were obtained by rupturing the covalent bond of phenanthrimidazole core to prevent aggregation-induced quenching. In DDIBPPIN, naphthonitrile group was incorporated into azomethine nitrogen of phenanthrimidazole to enhance charge-transfer ability. The DDIBPPIN/CBP:DDIBPPIN-based device shows blue emission with ηc (current e?ciency) of 4.91/4.10 cd/A, ηp (power e?ciency) of 4.56/3.84 lm/W, and ηex (external quantum e?ciency) of 5.11/5.96%. The ηs (exciton utilization e?ciency) values of DDIPNPPI and DDIBPPIN are of 27.0 and 30.3%, respectively. The DDIPNPPI and DDIBPPIN materials employed as a host to fabricate green and red phosphorescent organic light-emitting diodes. The red/white devices (with 0.4% dopant concentration) with DDIBPPIN:Ir(MDQ)2(acac) exhibit maximum L of 69889/26319 cd/m2, ηc of 34.6/35.6 cd/A, and ηp of 35.8/36.6 lm/W. The device with DDIBPPIN:Ir(ppy)3/DDIPNPPI:Ir(ppy)3 exhibits green emission [Commission Internationale de l’Eclairage (0.30,0.60)/(0.30,0.60)] with maximum L of 69906/69482 cd/m2, ηex of 17.9/17.0%, ηp of 63.6/61.3 lm/W. The white device using DDIBPPI:Ir(ppy)3 (with 0.4% dopant concentration) exhibits maximum L of 22152 cd/m2, ηc of 59.8/58.6 cd/A, and ηex of 19.6/16.6%, ηp of 36.1 lm/W.
关键词： phenanthrimidazole,charge-transfer ability,organic light-emitting diodes,fluorescent molecules,phosphorescent
更新于2025-09-11 14:15:04