Read by QxMD icon Read

Light-emitting diodes

Yan Fong Ng, Sneha A Kulkarni, Shayani Parida, Nur Fadilah Jamaludin, Natalia Yantara, Annalisa Bruno, Cesare Soci, Subodh Mhaisalkar, Nripan Mathews
The incorporation of phenylethylammonium bromide (PEABr) into a fully inorganic CsPbBr3 perovskite framework led to the formation of mixed-dimensional perovskites, which enhanced the photoluminescence due to efficient energy funnelling and morphological improvements. With a PEABr : CsPbBr3 ratio of 0.8 : 1, PeLEDs with a current efficiency of 6.16 cd A(-1) and an EQE value of 1.97% have been achieved.
October 20, 2017: Chemical Communications: Chem Comm
Chuanjiang Qin, Toshinori Matsushima, Atula S D Sandanayaka, Youichi Tsuchiya, Chihaya Adachi
The optical, structural, and electroluminescent (EL) characteristics of pure quasi-2D CsPb2Br5 were reported. We fabricated continuous, compact, well-crystalized CsPb2Br5 films by centrifugal coating from a colloidal solution containing CsPb2Br5 nanoparticles. The centrifugal-coated CsPb2Br5 films have a photoluminescence quantum yield (PLQY) of about 35% because of its low-dimensional structure. Taking advantage of the high PLQY, we fabricated perovskite light-emitting diodes (PeLEDs) with a centrifugal-coated CsPb2Br5 emitting layer exhibiting bright green EL, a maximum luminance of 7317 cd m-2, an external quantum efficiency of 1...
October 20, 2017: Journal of Physical Chemistry Letters
Maimunah Mohd Ali, Norhashila Hashim, Siti Khairunniza Bejo, Rosnah Shamsudin
The potential of laser light backscattering imaging was investigated for monitoring color parameters of seeded and seedless watermelons during storage. Two watermelon cultivars were harvested and stored for 3 weeks with seven measuring storage days (0, 4, 8, 12, 15, 18, and 21). The color parameters of watermelons were monitored using the conventional colorimetric methods (L*, a*, b*, C*, H*, and ∆E*) and laser light backscattering imaging system. A laser diode emitting at 658 nm and 30 mW power was used as a light source to obtain the backscattering image...
October 2017: Journal of Food Science and Technology
Ki Seok Kim, Ki Hyun Kim, You Jin Ji, Jin Woo Park, Jae Hee Shin, Albert Rogers Ellingboe, Geun Young Yeom
Depositing a barrier film for moisture protection without damage at a low temperature is one of the most important steps for organic-based electronic devices. In this study, the authors investigated depositing thin, high-quality SiNx film on organic-based electronic devices, specifically, very high-frequency (162 MHz) plasma-enhanced chemical vapor deposition (VHF-PECVD) using a multi-tile push-pull plasma source with a gas mixture of NH3/SiH4 at a low temperature of 80 °C. The thin deposited SiNx film exhibited excellent properties in the stoichiometry, chemical bonding, stress, and step coverage...
October 19, 2017: Scientific Reports
Francisco J Burgos-Fernández, Meritxell Vilaseca, Esther Perales, Elísabet Chorro, Francisco M Martínez-Verdú, José Fernández-Dorado, Jaume Pujol
In this study, a novel gonio-hyperspectral imaging system based on light-emitting diodes for the analysis of automotive coatings was validated colorimetrically and spectrally from 368 to 1309 nm. A total of 30 pearlescent, 30 metallic, and 30 solid real automotive coatings were evaluated with this system, the BYK-mac and X-Rite MA98 gonio-spectrophotometers, and also with the SPECTRO 320 spectrometer for further comparison. The results showed very precise correlations, especially in the visible range. In conclusion, this new system provides a deeper assessment of goniochromatic pigments than current approaches due to the expansion of the spectral range to the infrared...
September 1, 2017: Applied Optics
Junming Dong, Yanyu Zhang, Yijun Zhu
Visible light communications (VLC) using multi-color light-emitting diodes (LEDs) can support simultaneous high-speed data rate and high-quality lighting. However, since the radiation spectrum of LEDs has a limited width, spectral overlapping will result in multi-color cross talk even when optical filters are applied at the receivers. Moreover, since LEDs are used for illumination and wireless data transmission in the meantime, both lighting quality and communication performance must be considered in VLC systems...
August 10, 2017: Applied Optics
Xinghuo Ding, Chengqun Gui, Hongpo Hu, Mengling Liu, Xingtong Liu, Jiajiang Lv, Shengjun Zhou
Distributed Bragg reflectors (DBR) with metal film on the bottom have been demonstrated to further improve the light output power of GaN-based light-emitting diodes (LEDs). Periods of TiO2/SiO2 stacks, thickness of metal film, and material of metallic reflector were designed and optimized in simulation software. The maximal bandwidth of double-DBR stacks have reached up to 272 nm, which was 102 nm higher than a single-DBR stack. The average reflectance of LEDs with wavelength from 380 nm to 780 nm in double-DBR stacks is 95...
May 20, 2017: Applied Optics
Pengqiang Jiang, Yang Peng, Yun Mou, Hao Cheng, Mingxiang Chen, Sheng Liu
In this paper, we propose a thermally stable multi-color phosphor-in-glass (PiG) for chromaticity-tunable white light-emitting diodes (WLEDs). The multi-color PiG has a red, green, and blue (RGB) phosphor glass layer, which was screen-printed and co-sintered on a glass plate with a low temperature of 600°C. The WLED with ultra-compact structure was fabricated by the RGB-PiG directly bonded on a flip-chip ultraviolet (UV) LED. By controlling the weight ratio of R∶G∶B phosphors, the thickness of the RGB layer, and the weight ratio of phosphors to glass powders (PtG), the chromaticity of RGB-PiG based WLEDs can be effectively tuned with high color quality...
October 1, 2017: Applied Optics
Raphael Mansmann, Thomas Dreier, Christof Schulz
Photomultiplier tubes (PMTs) are widely used as detectors for laser-induced incandescence (LII), a diagnostics method for gas-borne particles that requires signal detection over a large dynamic range with nanosecond time resolution around the signal peak. Especially when more than one PMT is used (i.e., for pyrometric temperature measurements) even small deviations from the linear detector response can lead to significant errors. Reasons for non-linearity observed in other PMT measurement techniques are summarized and strategies to identify non-linear PMT operation in LII are outlined...
October 1, 2017: Applied Optics
Hyun Soo Lee, Hyun Jung Park, Joon Seop Kwak
Light-emitting diodes (LEDs) are causing big changes in the automotive lighting field. Optical systems with LEDs can use a plastic lens, which means almost all shapes can be made through plastic injection molding. Already, some car manufacturers are adopting this technology in their designs to express their own identities to customers. However, to use this technology, an important defect has to be overcome, which is color aberration near the cutoff line of the low-beam. In this paper, the criteria for measuring the color coordinates are established and simulations for axial color aberration in the plastic lens are carried out...
June 10, 2017: Applied Optics
Lei Jing, Yao Wang, Huifu Zhao, Hongliang Ke, Xiaoxun Wang, Qun Gao
In order to meet the requirements of uniform illumination for optical palm/fingerprint instruments and overcome the shortcomings of the poor uniform illumination on the working plane of the optical palm/fingerprint prism, a novel secondary optical lens with a free-form surface, compact structure, and high uniformity is presented in this paper. The design of the secondary optical lens is based on emission properties of the near-infrared light-emitting diode (LED) and basic principles of non-imaging optics, especially considering the impact of the thickness of the prism in the design...
June 10, 2017: Applied Optics
Daniela Karthaus, Markus Giehl, Oliver Sandfuchs, Stefan Sinzinger
The objective of applying transmission holograms in automotive headlamp systems requires the adaptation of holograms to divergent and polychromatic light sources like light-emitting diodes (LEDs). In this paper, four different options to describe the scalar light waves emitted by a typical automotive LED are regarded. This includes a new approach to determine the LED's wavefront from interferometric measurements. Computer-generated holograms are designed considering the different LED approximations and recorded into a photopolymer...
June 20, 2017: Applied Optics
Shang-Ping Ying, Han-Kuei Fu, Hsin-Hsin Hsieh, Kun-Yang Hsieh
The traditional white-light light-emitting diode (LED) is packaged with a single chip and a single phosphor but has a poor color rendering index (CRI). The next-generation package comprises two chips and a single phosphor, has a high CRI, and retains high luminous efficacy. This study employs two chips and two phosphors to improve the diode's color tunability with various proportions of two phosphors and various densities of phosphor in the silicone used. A color design model is established for color fine-tuning of the white-light LED module...
May 10, 2017: Applied Optics
Hiroshi Ohno
A compact light-emitting diode (LED) lighting module with a coaxial light guide that can produce a wide-angle light distribution is proposed. The structure of the coaxial light guide has a scattering area inside it and a tapered outer surface that is able to concentrate all of the rays on the scattering area owing to the total internal reflection. The rays diffused and reflected by the scattering area are refracted by the tapered outer surface and emitted in a wide-angle light distribution. A prototype of the LED lighting module was able to produce a point-like compact light source that radiates rays with half-intensity angle of 274° and lighting efficiency of 91%...
May 10, 2017: Applied Optics
Junjie Si, Yang Liu, Zhuofei He, Hui Du, Kai Du, Dong Chen, Jing Li, Mengmeng Xu, He Tian, Haiping He, Dawei Di, Changqing Lin, Yingchun Cheng, Jianpu Wang, Yizheng Jin
We report a facile solution-based approach to the in-situ growth of perovskite films consisting of monolayers of CsPbBr3 nanoplates passivated by bulky phenylbutylammonium (PBA) cations, i.e. two-dimensional layered PBA2(CsPbBr3)n-1PbBr4 perovskites. Optimizing film-formation processes leads to layered perovskites with controlled n values in the range of 12-16. The layered perovskite emitters show quantum-confined bandgap energies with a narrow distribution, suggesting the formation of thickness-controlled quantum-well (TCQW) structures...
October 18, 2017: ACS Nano
Armin Baumschlager, Stephanie K Aoki, Mustafa Khammash
Light has emerged as a control input for biological systems due to its precise spatiotemporal resolution. The limited toolset for light control in bacteria motivated us to develop a light-inducible transcription system that is independent from cellular regulation through the use of an orthogonal RNA polymerase. Here, we present our engineered blue light-responsive T7 RNA polymerases (Opto-T7RNAPs) that show properties such as low leakiness of gene expression in the dark state, high expression strength when induced with blue light, and an inducible range of more than 300-fold...
October 18, 2017: ACS Synthetic Biology
Nonglin Zhou, Shirong Wang, Yin Xiao, Xianggao Li
Aryl-substituted phenanthroimidazoles (PIs) have attracted tremendous attention in the field of organic light-emitting diodes (OLEDs) because they possess simple synthesis, excellent thermal properties, high photoluminescence quantum yields (PLQYs), and bipolar properties. Herein, a novel blue-green emitting material, (E)-2-(4'-(2-(anthracen-9-yl)vinyl)-[1,1'-biphenyl]-4-yl)-1-phenyl-1H-phenanthro[9,10-d]imidazole (APE-PPI), which contains t-APE (1-(9-anthryl)-2-phenylethene) core and PIs moiety, has been designed and synthesized...
October 17, 2017: Chemistry, An Asian Journal
Xian-Kai Chen, Youichi Tsuchiya, Yuma Ishikawa, Cheng Zhong, Chihaya Adachi, Jean-Luc Brédas
In the traditional molecular design of thermally activated delayed fluorescence (TADF) emitters composed of electron-donor and electron-acceptor moieties, achieving a small singlet-triplet energy gap (ΔEST ) in strongly twisted structures usually translates into a small fluorescence oscillator strength, which can significantly decrease the emission quantum yield and limit efficiency in organic light-emitting diode devices. Here, based on the results of quantum-chemical calculations on TADF emitters composed of carbazole donor and 2,4,6-triphenyl-1,3,5-triazine acceptor moieties, a new strategy is proposed for the molecular design of efficient TADF emitters that combine a small ΔEST with a large fluorescence oscillator strength...
October 17, 2017: Advanced Materials
Mustafa Ugur Daloglu, Aydogan Ozcan
Not only essential for scientific research, but also in the analysis of male fertility and for animal husbandry, sperm tracking and characterization techniques have been greatly benefiting from computational imaging. Digital image sensors, in combination with optical microscopy tools and powerful computers, have enabled the use of advanced detection and tracking algorithms that automatically map sperm trajectories and calculate various motility parameters across large data sets. Computational techniques are driving the field even further, facilitating the development of unconventional sperm imaging and tracking methods that do not rely on standard optical microscopes and objective lenses, which limit the field of view and volume of the semen sample that can be imaged...
August 1, 2017: Biology of Reproduction
Hyo-Min Kim, Jeonggi Kim, Sin-Young Cho, Jin Jang
We report the solution processed metal-oxide p-n junction, Li doped CuO (Li:CuO) and Li doped ZnO (Li:ZnO), as a charge generation junction (CGJ) in quantum-dot light-emitting diode (QLED) at reverse bias. Efficient charge generation is demonstrated in a stack of air annealed Li:CuO and Li:ZnO layers in QLEDs. Air annealing of Li:ZnO on Li:CuO turns out to be a key process to decrease the oxygen vacancy (Vo) and to increase the copper(II) oxide (CuO) fraction at the Li:CuO/Li:ZnO interface for efficient charge generation...
October 18, 2017: ACS Applied Materials & Interfaces
Fetch more papers »
Fetching more papers... Fetching...
Read by QxMD. Sign in or create an account to discover new knowledge that matter to you.
Remove bar
Read by QxMD icon Read

Search Tips

Use Boolean operators: AND/OR

diabetic AND foot
diabetes OR diabetic

Exclude a word using the 'minus' sign

Virchow -triad

Use Parentheses

water AND (cup OR glass)

Add an asterisk (*) at end of a word to include word stems

Neuro* will search for Neurology, Neuroscientist, Neurological, and so on

Use quotes to search for an exact phrase

"primary prevention of cancer"
(heart or cardiac or cardio*) AND arrest -"American Heart Association"