The Experts below are selected from a list of 2718 Experts worldwide ranked by ideXlab platform
Yue Wang - One of the best experts on this subject based on the ideXlab platform.
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novel emitting system based on a multifunctional bipolar phosphor an effective approach for highly efficient warm white light emitting devices with high Color Rendering Index at high luminance
Advanced Materials, 2016Co-Authors: Yansong Feng, Dongxia Zhu, Tai Peng, Yu Liu, Yue Wang, Martin R BryceAbstract:A three-Color warm-white organic light-emitting diode employing an efficient phosphor-phosphor type host-guest emitting system achieves efficiencies of 27.3% for external quantum efficiency and 74.5 lm W(-1) for power efficiency at a luminance of 1000 cd m(-2) , which maintained the high levels of 24.3% and 45.8 lm W(-1) at 10 000 cd m(-2) , with a stable Color-Rendering Index of 86-87.
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two host dopant emitting systems realizing four Color emission a simple and effective strategy for highly efficient warm white organic light emitting diodes with high Color Rendering Index at high luminance
ACS Applied Materials & Interfaces, 2016Co-Authors: Xuming Zhuang, Yu Liu, Hao Zhang, Yue WangAbstract:A four-Color warm-white organic light-emitting diode employing a simple adjacent two-emitting-layer structure as a blue host–orange dopant/green host–red dopant has been fabricated, which exhibited a stable high electroluminescent performance: an external quantum efficiency of 23.3% and a power efficiency of 63.2 lm W–1 at an illumination-relevant luminance of 1000 cd m–2 with a high Color-Rendering Index (CRI) of 92 and maintained high levels of 21.6% and 48.8 lm W–1 with a CRI value of 93 at the extremely high luminance of 5000 cd m–2. To our knowledge, this should be the best result so far for a white-light organic light-emitting diode with CRI > 90, simultaneously exhibiting very high efficiencies based on a high luminance level for the solid-state lighting.
R S Liu - One of the best experts on this subject based on the ideXlab platform.
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control of narrow band emission in phosphor materials for application in light emitting diodes
ACS energy letters, 2018Co-Authors: Mu-huai Fang, R S Liu, Julius L LeanoAbstract:Light-emitting diodes (LEDs) are widely used around the world. Scientists are attempting to develop LED devices that not only have high brightness but also have a high Color Rendering Index (CRI). ...
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facile atmospheric pressure synthesis of high thermal stability and narrow band red emitting srlial3n4 eu2 phosphor for high Color Rendering Index white light emitting diodes
ACS Applied Materials & Interfaces, 2016Co-Authors: Xuejie Zhang, Yiting Tsai, Yinchih Lin, Jyhfu Lee, Hwoshuenn Sheu, Bingming Cheng, R S LiuAbstract:Red phosphors (e.g., SrLiAl3N4:Eu2+) with high thermal stability and narrow-band properties are urgently explored to meet the next-generation high-power white light-emitting diodes (LEDs). However, to date, synthesis of such phosphors remains an arduous task. Herein, we report, for the first time, a facile method to synthesize SrLiAl3N4:Eu2+ through Sr3N2, Li3N, Al, and EuN under atmospheric pressure. The as-synthesized narrow-band red-emitting phosphor exhibits excellent thermal stability, including small chromaticity shift and low thermal quenching. Intriguingly, the title phosphor shows an anomalous increase in theoretical lumen equivalent with the increase of temperature as a result of blue shift and band broadening of the emission band, which is crucial for high-power white LEDs. Utilizing the title phosphor, commercial YAG:Ce3+, and InGaN-based blue LED chip, a proof-of-concept warm white LEDs with a Color Rendering Index (CRI) of 91.1 and R9 = 68 is achieved. Therefore, our results highlight that t...
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emission tunable cuins2 zns quantum dots structure optical properties and application in white light emitting diodes with high Color Rendering Index
ACS Applied Materials & Interfaces, 2014Co-Authors: Po Hsiang Chuang, Chun Che Lin, R S LiuAbstract:Synthesis and application of CuInS2/ZnS core/shell quantum dots (QDs) with varying [Cu]/[In] ratios were conducted using a stepwise solvothermal route. CuInS2 (CIS) core QDs with varying [Cu]/[In] ratios exhibited deep-red emissions result from donor–acceptor pair recombination. The absorption and emission band gap of the CuInS2 QDs increased with the decrease in Cu content. The emission bands of the CuInS2/ZnS were tuned from 550 to 616 nm by controlling the [Cu]/[In] ratio after coating ZnS layer. The CIS QDs model was developed to elucidate the synthesized crystal structure and photoluminescence of the QDs with various [Cu]/[In] ratios. Temperature-dependent photoluminescence spectra of the CIS/ZnS QDs were also investigated. The temperature dependency of the photoluminescence energy and intensity for various CIS/ZnS QDs were studied from 25 to 200 °C. Efficient white light-emitting diodes with high Color Rendering Index values (Ra = 90) were fabricated using CIS/ZnS QDs as Color converters in combinat...
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origin of thermal degradation of sr2 xsi5n8 eux phosphors in air for light emitting diodes
Journal of the American Chemical Society, 2012Co-Authors: Chiao Wen Yeh, R S Liu, Hwoshuenn Sheu, Wei Ting Chen, J M Chen, Hubertus T HintzenAbstract:The orange-red emitting phosphors based on M2Si5N8:Eu (M = Sr, Ba) are widely utilized in white light-emitting diodes (WLEDs) because of their improvement of the Color Rendering Index (CRI), which ...
Hilmi Volkan Demir - One of the best experts on this subject based on the ideXlab platform.
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high scotopic photopic ratio white light emitting diodes integrated with semiconductor nanophosphors of colloidal quantum dots
Optics Letters, 2011Co-Authors: Sedat Nizamoglu, Talha Erdem, Hilmi Volkan DemirAbstract:We propose and demonstrate single-chip white-light-emitting diodes (WLEDs) integrated with semiconductor nanophosphors of colloidal quantum dots for high scotopic/photopic (S/P) ratio. These Color conversion WLEDs achieve S/P ratios over 3.00, which exceeds the current limit of 2.50 in common lighting technologies, while sustaining sufficient levels of Color Rendering Index.
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warm white light emitting diodes integrated with colloidal quantum dots for high luminous efficacy and Color Rendering
Optics Letters, 2010Co-Authors: Sedat Nizamoglu, Talha Erdem, Xiao Wei Sun, Hilmi Volkan DemirAbstract:Warm-white LEDs (WLEDs) with high spectral quality and efficiency are required for lighting applications, but current experimental performances are limited. We report on nanocrystal quantum dot (NQD) hybridized WLEDs with high performance that exhibit a high luminous efficacy of optical radiation exceeding 350lm/Wopt and a high Color Rendering Index close to 90 at a low correlated Color temperature <3000K. These spectrally engineered WLEDs are obtained using a combination of CdSe/ZnS core/shell NQD nanophosphors integrated on blue InGaN/GaN LEDs.
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a photometric investigation of ultra efficient leds with high Color Rendering Index and high luminous efficacy employing nanocrystal quantum dot luminophores
Optics Express, 2010Co-Authors: Talha Erdem, Sedat Nizamoglu, Xiao Wei Sun, Hilmi Volkan DemirAbstract:We report a photometric study of ultra-efficient light emitting diodes (LEDs) that exhibit superior Color Rendering Index (CRI) and luminous efficacy of optical radiation (LER) using semiconductor quantum dot nanocrystal (NC) luminophores. Over 200 million systematically varied NC-LED designs have been simulated to understand feasible performance in terms of CRI vs. LER. We evaluated the effects of design parameters including peak emission wavelength, full-width-at-half-maximum, and relative amplitudes of each NC Color component on LED performance. Warm-white LEDs with CRI >90 and LER >380 lm/W at a correlated Color temperature of 3000 K are shown to be achieved using nanocrystal luminophores.
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Color converting combinations of nanocrystal emitters for warm white light generation with high Color Rendering Index
Applied Physics Letters, 2008Co-Authors: Sedat Nizamoglu, Gulis Zengin, Hilmi Volkan DemirAbstract:Warm-white light emitting diodes with high Color Rendering indices are required for the widespread use of solid state lighting especially indoors. To meet these requirements, we propose and demonstrate warm-white hybrid light sources that incorporate the right Color-converting combinations of CdSe∕ZnS core-shell nanocrystals hybridized on InGaN∕GaN LEDs for high Color Rendering Index. Three sets of proof-of-concept devices are developed to generate high-quality warm-white light with (1) tristimulus coordinates (x,y)=(0.37,0.30), luminous efficacy (LE)=307lm∕W, Color rending Index (CR)=82.4, and correlated Color temperature (CCT)=3228K; (2) (x,y)=(0.38,0.31), LE=323lm∕W, CRI=81.0, and CCT=3190K; and (3) (x,y)=(0.37,0.30), LE=303lm∕W, CRI=79.6, and CCT=1982K.
Woon Jin Chung - One of the best experts on this subject based on the ideXlab platform.
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a low sintering temperature glass based on sio2 p2o5 zno b2o3 r2o system for white leds with high Color Rendering Index
Journal of the American Ceramic Society, 2017Co-Authors: Seonghyeon Kim, Hyun A Park, Jong Heo, Jaeyoung Choi, Woon Jin ChungAbstract:A low sintering temperature glass based on the SiO2-P2O5-ZnO-B2O3-R2O (R=K and Na) system was studied as a matrix for embedding phosphors to fabricate Color tunable white LEDs. The proposed system, which uses no heavy metal elements and can be sintered at 500 °C, incorporates thermally weak commercial phosphors such as CaAlSiN3:Eu2+ to produce phosphor-in-glasses (PiGs). Changing the mixing ratio of glass to phosphors affected the photo-luminescence spectra and Color coordinates of the PiGs when mounted on a blue LED. The Color Rendering Index (CRI) and Color correlated temperature (CCT) of the LEDs were also varied with the mixing ratio, providing Color tunable white LEDs. A high CRI, up to 93, as well as highly improved thermal stability were obtained, along with a low sintering temperature compared to other glass systems, suggesting the practical feasibility of the proposed system. This article is protected by copyright. All rights reserved.
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improved Color Rendering Index and thermal stability of white leds with phosphor in glass using the sio2 b2o3 zno na2o glass system
Journal of Non-crystalline Solids, 2016Co-Authors: Karam Han, Sang Hun Lee, Yong Gyu Choi, Woon Jin ChungAbstract:Abstract Phosphor in glasses (PiGs) were fabricated for Color tunable white LEDs using glass of the SiO2-B2O3-ZnO-Na2O system, which can be sintered at 550 °C. CaAlSiN3:Eu2 + (CASN:Eu2 +) red phosphor was added without its thermal degradation, and a mixture with Y3Al5O12:Ce3 + (YAG:Ce3 +) yellow phosphor demonstrated Color tunable white LEDs when mounted on a blue LED. Variation of the glass to phosphor and phosphor to phosphor mixing ratio achieved a highly improved Color Rendering Index (CRI), of up to 93. Thermal quenching property was also improved, reaching 98% of its original intensity even at 200 °C; the value depended on the phosphor content. Thermal conductivity values elucidate the improvement.
Yu Liu - One of the best experts on this subject based on the ideXlab platform.
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novel emitting system based on a multifunctional bipolar phosphor an effective approach for highly efficient warm white light emitting devices with high Color Rendering Index at high luminance
Advanced Materials, 2016Co-Authors: Yansong Feng, Dongxia Zhu, Tai Peng, Yu Liu, Yue Wang, Martin R BryceAbstract:A three-Color warm-white organic light-emitting diode employing an efficient phosphor-phosphor type host-guest emitting system achieves efficiencies of 27.3% for external quantum efficiency and 74.5 lm W(-1) for power efficiency at a luminance of 1000 cd m(-2) , which maintained the high levels of 24.3% and 45.8 lm W(-1) at 10 000 cd m(-2) , with a stable Color-Rendering Index of 86-87.
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two host dopant emitting systems realizing four Color emission a simple and effective strategy for highly efficient warm white organic light emitting diodes with high Color Rendering Index at high luminance
ACS Applied Materials & Interfaces, 2016Co-Authors: Xuming Zhuang, Yu Liu, Hao Zhang, Yue WangAbstract:A four-Color warm-white organic light-emitting diode employing a simple adjacent two-emitting-layer structure as a blue host–orange dopant/green host–red dopant has been fabricated, which exhibited a stable high electroluminescent performance: an external quantum efficiency of 23.3% and a power efficiency of 63.2 lm W–1 at an illumination-relevant luminance of 1000 cd m–2 with a high Color-Rendering Index (CRI) of 92 and maintained high levels of 21.6% and 48.8 lm W–1 with a CRI value of 93 at the extremely high luminance of 5000 cd m–2. To our knowledge, this should be the best result so far for a white-light organic light-emitting diode with CRI > 90, simultaneously exhibiting very high efficiencies based on a high luminance level for the solid-state lighting.