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https://www.readbyqxmd.com/read/28535346/on-the-optimization-of-current-injection-in-algainp-core-shell-nanowire-light-emitting-diodes
#1
Pyry Kivisaari, Alexander Berg, Mohammad Karimi, Kristian Storm, Steven Limpert, Jani Oksanen, Lars Samuelson, Håkan Jan Pettersson, Magnus T Borgström
Core-shell nanowires offer great potential to enhance the efficiency of light-emitting diodes (LEDs) and expand the attainable wavelength range of LEDs over the whole visible spectrum. Additionally, nanowire LEDs can offer both improved light extraction and emission enhancement if the diameter of the wires is not larger than half the emission wavelength (λ/2). However, AlGaInP nanowire LEDs have so far failed to match the high efficiencies of traditional planar technologies, and the parameters limiting the efficiency remain unidentified...
May 23, 2017: Nano Letters
https://www.readbyqxmd.com/read/28535341/fully-stretchable-optoelectronic-sensors-based-on-colloidal-quantum-dots-for-sensing-photoplethysmographic-signals
#2
Tae-Ho Kim, Chang-Seok Lee, Sangwon Kim, Jaehyun Hur, Sangmin Lee, Keun Wook Shin, Young-Zoon Yoon, Moon Kee Choi, Jiwoong Yang, Dae-Hyeong Kim, Taeghwan Hyeon, Seongjun Park, Sungwoo Hwang
Flexible and stretchable optoelectronic devices can be potentially applied in displays, biosensors, biomedicine, robotics, and energy generation. The use of nanomaterials with superior optical properties such as quantum dots (QDs) is important in the realization of wearable displays and biomedical devices, but specific structural design as well as selection of materials should preferentially accompany this technology to realize stretchable forms of these devices. Here, we report stretchable optoelectronic sensors manufactured using colloidal QDs and integrated with elastomeric substrates, whose optoelectronic properties are stable under various deformations...
May 23, 2017: ACS Nano
https://www.readbyqxmd.com/read/28534904/porous-copper-graphene-heterostructures-for-cooling-of-electronic-devices
#3
Hokyun Rho, Yea Sol Jang, Sungmin Kim, Sukang Bae, Tae-Wook Kim, Dong Su Lee, Jun-Seok Ha, Sang Hyun Lee
Recently, research on micro-electronic and optoelectronic devices has been rapidly increasing. Parts and products related to these devices are becoming smaller and more integrated within circuits. As a result, the heat generated in devices has increased greatly. When excess heat is generated, important properties are affected such as efficiency and lifetime and, in severe cases, this can result in the failure of devices. Therefore, efficient cooling is required and it becomes necessary to study the heat dissipation properties of device materials...
May 23, 2017: Nanoscale
https://www.readbyqxmd.com/read/28532145/mini-photobioreactors-for-in-vivo-real-time-characterization-and-evolutionary-tuning-of-bacterial-optogenetic-circuit
#4
Hsinkai Wang, Ya-Tang Yang
The current standard protocols for characterizing the optogenetic circuit of bacterial cells using flow cytometry in light tubes and light exposure of culture plates are tedious, labor-intensive, and cumbersome. In this work, we engineer a bioreactor with working volume of ~10 mL for in vivo real-time optogenetic characterization of E. coli with a CcaS-CcaR light-sensing system. In the bioreactor, optical density measurements, reporter protein fluorescence detection, and light input stimuli are provided by four light-emitting diode sources and two photodetectors...
May 22, 2017: ACS Synthetic Biology
https://www.readbyqxmd.com/read/28527873/comparison-of-xenon-with-led-illuminant-in-difficult-and-inhalation-injury-airway-scenario-a-randomized-crossover-manikin-study
#5
Andreas Moritz, Johannes Prottengeier, Joachim Schmidt
PURPOSE: The purpose of this study was to compare the effectiveness of a Xenon halogen with a light-emitting diode (LED) laryngoscope light handle in a difficult airway scenario, as well as in an inhalation injury airway scenario that combines a difficult airway and a limited view. METHODS: We recruited forty-two anesthetists into a randomized crossover trial. Each performed tracheal intubation (TI) with a Xenon halogen and a LED light handle in the two manikin scenarios...
May 8, 2017: American Journal of Emergency Medicine
https://www.readbyqxmd.com/read/28527280/-pperformance-of-led-fluorescence-microscopy-for-the-detection-of-acid-fast-bacilli-from-respiratory-samples-in-peripheral-laboratories-in-argentina
#6
María Imaz, Sonia Allassia, Mónica Aranibar, Alba Gunia, Susana Poggi, Ana Togneri, Lidia Wolff, Group Of Implementation Of Fluorescence
INTRODUCTION: Light-emitting diode fluorescence microscopy (LED-FM) has been endorsed by the World Health Organization (WHO) for tuberculosis diagnosis, but its accuracy in HIV-infected patients remains controversial, and only some few studies have explored procedural factors that may affect its performance. OBJECTIVE: To evaluate the performance of LED-FM for tuberculosis diagnosis in patients with and without HIV infection using a newer, less expensive LED lamp...
June 1, 2017: Biomédica: Revista del Instituto Nacional de Salud
https://www.readbyqxmd.com/read/28524654/polyethylenimine-insulativity-dominant-charge-injection-balance-for-highly-efficient-inverted-quantum-dot-light-emitting-diodes
#7
Ke Ding, Hongting Chen, Lianwei Fan, Bo Wang, Zhi Huang, Shaoqing Zhuang, Bin Hu, Lei Wang
Quantum dot light emitting diode (QLED) with an inverted architecture always suffers charge injection imbalance and severe quantum dot charging, which degrades device performance. Blocking excess injected electrons into quantum dots (QDs) is crucial for efficient inverted QLEDs. It is found that Polyethylenimine (PEI) has two opposite effect on electron injection, one is blocking electron injection by its intrinsic insulativity and the other one is promoting electron injection by the reduced work function of ZnO/PEI...
May 19, 2017: ACS Applied Materials & Interfaces
https://www.readbyqxmd.com/read/28523914/polymerizable-supramolecular-approach-to-highly-conductive-pedot-pss-patterns
#8
Taegeun Kim, Suryong Ha, Hyosung Choi, Kyungchan Uh, Umesha Kundapur, Sumin Park, Chan Woo Lee, Sang-Hwa Lee, Jaeyong Kim, Jong-Man Kim
Owing to its high conductivity, solution processability, mechanical flexibility and transparency, poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) has been extensively explored for use in functional devices including solar cells, sensors, light emitting diodes and supercapacitors. The ability to fabricate patterned PEDOT:PSS on a solid substrate is of significant importance in order to develop practical applications of this conducting polymer. Herein we describe a new approach to obtain PEDOT:PSS patterns that is based on a polymerizable supramolecular concept...
May 19, 2017: ACS Applied Materials & Interfaces
https://www.readbyqxmd.com/read/28523285/electrically-pumped-wavelength-tunable-gaas-quantum-dots-interfaced-with-rubidium-atoms
#9
Huiying Huang, Rinaldo Trotta, Yongheng Huo, Thomas Lettner, Johannes S Wildmann, Javier Martín-Sánchez, Daniel Huber, Marcus Reindl, Jiaxiang Zhang, Eugenio Zallo, Oliver G Schmidt, Armando Rastelli
We demonstrate the first wavelength-tunable electrically pumped source of nonclassical light that can emit photons with wavelength in resonance with the D2 transitions of (87)Rb atoms. The device is fabricated by integrating a novel GaAs single-quantum-dot light-emitting diode (LED) onto a piezoelectric actuator. By feeding the emitted photons into a 75 mm long cell containing warm (87)Rb vapor, we observe slow-light with a temporal delay of up to 3.4 ns. In view of the possibility of using (87)Rb atomic vapors as quantum memories, this work makes an important step toward the realization of hybrid-quantum systems for future quantum networks...
March 15, 2017: ACS Photonics
https://www.readbyqxmd.com/read/28522838/fabrication-of-full-color-gan-based-light-emitting-diodes-on-nearly-lattice-matched-flexible-metal-foils
#10
Hyeryun Kim, Jitsuo Ohta, Kohei Ueno, Atsushi Kobayashi, Mari Morita, Yuki Tokumoto, Hiroshi Fujioka
GaN-based light-emitting diodes (LEDs) have been widely accepted as highly efficient solid-state light sources capable of replacing conventional incandescent and fluorescent lamps. However, their applications are limited to small devices because their fabrication process is expensive as it involves epitaxial growth of GaN by metal-organic chemical vapor deposition (MOCVD) on single crystalline sapphire wafers. If a low-cost epitaxial growth process such as sputtering on a metal foil can be used, it will be possible to fabricate large-area and flexible GaN-based light-emitting displays...
May 18, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28521088/highly-promoting-the-performances-of-polymer-light-emitting-diodes-via-controlling-the-residue-of-polar-solvent-on-emissive-layer
#11
Qiaoli Niu, Hengsheng Wu, Wentao Huang, Jing Tong, Fengye Ye, Yong Zhang, Wenjin Zeng, Ruidong Xia, Yonggang Min
Polar solvent dimethyl formamide (DMF) was used to treat the emissive layer (EML) of polymer light-emitting diode (PLED). The formation of dipole layer at the EML/cathode interface after DMF treatment was proved, which led to a reduction of electron injection barrier. The dipole layer was formed mainly because of the intrinsic polarity of DMF. By controlling the residue of DMF on the EML, a maximum enhancement of peak luminous efficiency from 5.33±0.57 to 12.05±1.2 cd/A was achieved. This study suggests that solvent treatment is a simple and efficient approach to realize highly efficient PLEDs with high-work-function metal cathode...
May 18, 2017: ACS Applied Materials & Interfaces
https://www.readbyqxmd.com/read/28517016/graphene-as-an-electrode-for-solution-processed-electron-transporting-organic-transistors
#12
Subir Parui, Mário Ribeiro, Ainhoa Atxabal, Roger Llopis, Fèlix Casanova, Luis E Hueso
Organic field-effect transistors (OFETs) are fundamental building blocks for plastic electronics such as organic photovoltaics or bendable displays with organic light emitting diodes, and radio-frequency identification (RFID) tags. A key part in the performance of OFET is the organic material constituting the channel. OFETs based on solution-processed polymers represent a new class of organic electronic devices. Recent developments in upscale solution-processed polymers have advanced towards high throughput, low-cost, and environmentally friendly materials for high-performance applications...
May 18, 2017: Nanoscale
https://www.readbyqxmd.com/read/28516899/all-dielectric-resonant-cavity-enabled-metals-with-broadband-optical-transparency
#13
Zhengqi Liu, Houjiao Zhang, Xiaoshan Liu, Pingping Pan, Yi Liu, Li Tang, Guiqiang Liu
Metal films with broadband optical transparency are desirable in many optoelectronic devices, such as displays, smart windows, light-emitting diodes and infrared detectors. As bare metal is opaque to light, this issue of transparency attracts great scientific interest. In this work, we proposed and demonstrated a feasible and universal approach for achieving broadband optical transparent (BOT) metals by utilizing all-dielectric resonant cavities. Resonant dielectrics provide optical cavity modes and couple strongly with the surface plasmons of the metal film, and therefore produce a broadband near-unity optical transparent window...
May 18, 2017: Nanotechnology
https://www.readbyqxmd.com/read/28516461/effects-of-high-g-impact-on-physical-electrical-and-optical-characteristics-of-light-emitting-diodes
#14
Xin Wen, Brandon Okraszewski, Pragun Babber, James Cash, Stephen Cain, David Klotzkin
Previously, one of the tools available in automotive or aircraft accident analysis was the examination of the indicator bulbs. Currently, indicator bulbs have been largely replaced by light-emitting diodes (LEDs). Here a series of studies was carried out on impact effects on LEDs to determine whether their properties change after impact, and whether it is related to its working status (lit or unlit). The LEDs were measured before mechanical shock with a series of tests, including current-voltage, current-light, bandwidth, subject to impact ranging from 450 g to 2000 g, and then retested...
May 18, 2017: Journal of Forensic Sciences
https://www.readbyqxmd.com/read/28514161/interdiffusion-reaction-assisted-hybridization-of-two-dimensional-metal-organic-frameworks-and-ti3c2tx-nanosheets-for-electrocatalytic-oxygen-evolution
#15
Li Zhao, Biliang Dong, Shaozhou Li, Lijun Zhou, Linfei Lai, Zhiwei Wang, Shulin Zhao, Min Han, Kai Gao, Min Lu, Xiaoji Xie, Bo Chen, Zhengdong Liu, Xiangjing Wang, Hao Zhang, Hai Li, Juqing Liu, Hua Zhang, Xiao Huang, Wei Huang
Two-dimensional (2D) metal-organic framework (MOF) nanosheets have been recently regarded as the model electrocatalysts due to their porous structure, fast mass and ion transfer through the thickness, and large portion of exposed active metal centers. Combining them with electrically conductive 2D nanosheets is anticipated to achieve further improved performance in electrocatalysis. In this work, we in situ hybridized 2D cobalt 1,4-benzenedicarboxylate (CoBDC) with Ti3C2Tx (the MXene phase) nanosheets via an interdiffusion reaction-assisted process...
May 22, 2017: ACS Nano
https://www.readbyqxmd.com/read/28514138/manipulating-ion-migration-for-highly-stable-light-emitting-diodes-with-single-crystalline-organometal-halide-perovskite-microplatelets
#16
Mingming Chen, Xin Shan, Thomas Geske, Junqiang Li, Zhibin Yu
Ion migration has been commonly observed as a detrimental phenomenon in organometal halide perovskite semiconductors, causing the measurement hysteresis in solar cells and ultrashort operation lifetimes in light-emitting diodes. In this work, ion migration is utilized for the formation of a p-i-n junction at ambient temperature in single-crystalline organometal halide perovskites. The junction is subsequently stabilized by quenching the ionic movement at a low temperature. Such a strategy of manipulating the ion migration has led to efficient single-crystalline light-emitting diodes that emit 2...
May 22, 2017: ACS Nano
https://www.readbyqxmd.com/read/28514135/three-dimensional-hetero-integration-of-faceted-gan-on-si-pillars-for-efficient-light-energy-conversion-devices
#17
Dong Rip Kim, Chi Hwan Lee, In Sun Cho, Hanmin Jang, Min Soo Jeon, Xiaolin Zheng
An important pathway for cost-effective light energy conversion devices, such as solar cells and light emitting diodes, is to integrate III-V (e.g., GaN) materials on Si substrates. Such integration first necessitates growth of high crystalline III-V materials on Si, which has been the focus of many studies. However, the integration also requires that the final III-V/Si structure has a high light energy conversion efficiency. To accomplish these twin goals, we use single-crystalline microsized Si pillars as a seed layer to first grow faceted Si structures, which are then used for the heteroepitaxial growth of faceted GaN films...
May 22, 2017: ACS Nano
https://www.readbyqxmd.com/read/28513980/solid-state-carbon-dots-with-red-fluorescence-and-efficient-construction-of-dual-fluorescence-morphologies
#18
Jiangling He, Youling He, Yonghao Chen, Bingfu Lei, Jianle Zhuang, Yong Xiao, Yeru Liang, Mingtao Zheng, Haoran Zhang, Yingliang Liu
Stable solid-state red fluorescence from organosilane-functionalized carbon dots (CDs) with sizes around 3 nm is reported for the first time. Meanwhile, a novel method is also first reported for the efficient construction of dual-fluorescence morphologies. The quantum yield of these solid-state CDs and their aqueous solution is 9.60 and 50.7%, respectively. The fluorescence lifetime is 4.82 ns for solid-state CDs, and 15.57 ns for their aqueous solution. These CDs are detailedly studied how they can exhibit obvious photoluminescence overcoming the self-quenching in solid state...
May 17, 2017: Small
https://www.readbyqxmd.com/read/28513655/boron-difluoride-hemicurcuminoid-as-an-efficient-far-red-to-near-infrared-emitter-toward-oleds-and-laser-dyes
#19
A D'Aléo, M H Sazzad, D H Kim, E Y Choi, J W Wu, G Canard, F Fages, J-C Ribierre, C Adachi
A hemicurcuminoid boron difluoride complex is used as an emitter in organic light-emitting diodes, showing far red/near-infrared electroluminescence with an external quantum efficiency as high as 2.1%. This dye blended in CBP thin films shows amplified spontaneous emission with a threshold of 22 μJ cm(-2) at 750 nm, making this compound attractive for organic semiconductor lasers operating in the near-infrared region.
May 17, 2017: Chemical Communications: Chem Comm
https://www.readbyqxmd.com/read/28513086/photoluminescent-properties-of-novel-design-heteroleptic-zn-ii-complexes
#20
Atul C Vamja, Kiran R Surati
Three novel heteroleptic Zn(II) complexes containing 8-hydroxy quinoline and various pyrazolone-based derivatives were synthesized and their structures confirmed by (1) H-nuclear magnetic resonance, mass spectrometry, Fourier transform infra-red spectroscopy, UV-vis analysis and element analysis. All three complexes showed good photoluminescence properties in the solid state and in solution in the maximum emission range from 475 to 490 nm with a quantum yield of 0.45 to 0.51. Absorption spectra revealed that the complexes possessed a maximum absorption range of 272-281 nm with a band gap of 2...
May 16, 2017: Luminescence: the Journal of Biological and Chemical Luminescence
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