The Experts below are selected from a list of 190287 Experts worldwide ranked by ideXlab platform
Mischa M. Megens - One of the best experts on this subject based on the ideXlab platform.
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iii nitride photonic crystal Light Emitting Diodes with high extraction efficiency
Nature Photonics, 2009Co-Authors: Jonathan J Wierer, Aurelien J F David, Mischa M. MegensAbstract:Blue Light-Emitting Diodes with a Light extraction efficiency of 73% are reported. The InGaN–GaN devices use a photonic-crystal structure for superior optical mode control; their performance has been characterized experimentally and modelled theoretically.
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III-nitride photonic-crystal Light-Emitting Diodes with high extraction efficiency
Nature Photonics, 2009Co-Authors: JR. JONATHAN J WIERER, Aurelien David, Mischa M. MegensAbstract:Light-Emitting Diodes are becoming an increasingly attractive alternative to conventional Light sources due to their small size, high efficiency and long lifetime. Ongoing research is dedicated to improving their performance through the use of more efficient Light-generating and Light-extracting structures. Here, we demonstrate Light-Emitting Diodes achieving high extraction efficiency by using photonic crystals. The structures are iii-nitride thin-film Light-Emitting Diodes Emitting at = 450 nm. The photonic-crystal layer provides superior optical mode control compared to conventional iii-nitride Light-Emitting Diodes, efficiently coupling guided modes out of the Light-Emitting diode. Fabry–Perot and photonic-crystal induced modes are observed in the far-field radiation patterns and are matched to theoretical electromagnetic calculations. The optical mode control results in a high-performance Light-Emitting diode with an estimated unencapsulated Light extraction of 73%, higher than any unencapsulated iii-nitride Light-Emitting diode measured to date.
Samson A Jenekhe - One of the best experts on this subject based on the ideXlab platform.
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phenoxazine based emissive donor acceptor materials for efficient organic Light Emitting Diodes
Chemistry of Materials, 2005Co-Authors: And Abhishek P Kulkarni, Samson A JenekheAbstract:Bright and efficient green Light-Emitting Diodes were achieved from the intramolecular charge-transfer fluorescence of new donor−acceptor molecules incorporating phenoxazine as the donor and phenylquinoline as the acceptor.
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Phenoxazine-Based Emissive Donor−Acceptor Materials for Efficient Organic Light-Emitting Diodes
Chemistry of Materials, 2005Co-Authors: And Abhishek P Kulkarni, Samson A JenekheAbstract:Bright and efficient green Light-Emitting Diodes were achieved from the intramolecular charge-transfer fluorescence of new donor−acceptor molecules incorporating phenoxazine as the donor and phenylquinoline as the acceptor.
Chul Woong Joo - One of the best experts on this subject based on the ideXlab platform.
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Color temperature tunable white organic Light-Emitting Diodes
Organic Electronics, 2013Co-Authors: Chul Woong Joo, Jun-Han Han, Joohyun Hwang, J W Huh, Jaehyun Moon, Nam Sung Cho, H Y ChuAbstract:In this work, we demonstrated color-tunable white organic Light-Emitting Diodes by stacking upper orange transparent and lower blue bottom emission organic Light-Emitting Diodes (OLEDs). By independently operating each OLED, it was possible to tune the color temperature in a range of 1500–10,000K, which covers the full Planckian locus in the 1931 CIE space. In designing stable and efficient OLEDs, in addition to the electrical characteristics, the importance of internal microcavity was emphasized and implemented. In fabricating the upper transparent OLED, special attention was paid to the capping layer for enhancing the emission. Our results presented a general guideline that is practically useful in designing high-performance color-tunable OLEDs with transparent OLEDs.
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Multilayer stacked white polymer Light-Emitting Diodes
Journal of Physics D: Applied Physics, 2009Co-Authors: Chul Woong Joo, Soon Ok Jeon, Kyoung Soo Yook, Jun Yeob LeeAbstract:Multilayer stacked white polymer Light-Emitting Diodes (WPLEDs) with a multilayer Emitting structure were produced using a stamp transfer printing process. Two Light-Emitting layers were stacked using a transfer printing method, and the device performance of the WPLEDs was examined. Yellow Light-Emitting polymers spin coated onto silicone substrates were transferred to a polydimethylsiloxane stamp, which was transferred effectively to the top of blue polymers. White colour coordinates of (0.34, 0.41) were obtained from the multilayer stacked WPLEDs.
Frank W. Wise - One of the best experts on this subject based on the ideXlab platform.
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Bright infrared quantum-dot Light-Emitting Diodes through inter-dot spacing control
Nature Nanotechnology, 2012Co-Authors: Liangfeng Sun, Byung-ryool Hyun, Adam C. Bartnik, Joshua J. Choi, David Stachnik, Tobias Hanrath, George G. Malliaras, Frank W. WiseAbstract:Infrared Light-Emitting Diodes are currently fabricated from direct-gap semiconductors using epitaxy, which makes them expensive and difficult to integrate with other materials. Light-Emitting Diodes based on colloidal semiconductor quantum dots, on the other hand, can be solution-processed at low cost, and can be directly integrated with silicon. However, so far, exciton dissociation and recombination have not been well controlled in these devices, and this has limited their performance. Here, by tuning the distance between adjacent PbS quantum dots, we fabricate thin-film quantum-dot Light-Emitting Diodes that operate at infrared wavelengths with radiances (6.4 W sr(-1) m(-2)) eight times higher and external quantum efficiencies (2.0%) two times higher than the highest values previously reported. The distance between adjacent dots is tuned over a range of 1.3 nm by varying the lengths of the linker molecules from three to eight CH(2) groups, which allows us to achieve the optimum balance between charge injection and radiative exciton recombination. The electroluminescent powers of the best devices are comparable to those produced by commercial InGaAsP Light-Emitting Diodes. By varying the size of the quantum dots, we can tune the emission wavelengths between 800 and 1,850 nm.
D. W. Kisker - One of the best experts on this subject based on the ideXlab platform.
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Hybrid organic-inorganic semiconductor-based Light-Emitting Diodes
Journal of Applied Physics, 1997Co-Authors: Subhendu Guha, Richard A Haight, Nestor A. Bojarczuk, D. W. KiskerAbstract:We demonstrate that the ability of GaN-based Light-Emitting Diodes to emit in the shea-wavelength regime makes possible ''hybrid'' organic- inorganic semiconductor Light-Emitting Diodes that consist of two parts: a GaN-based electroluminescent part and an organic thin-film-based fluorescent part that absorbs the electroluminescence and fluoresces at a longer wavelength resulting in color conversion. We also show that organic films with much improved surface smoothness may be obtained by deposition at reduced temperatures. (C) 1997 American Institute of Physics.
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Hybrid organic–inorganic semiconductor-based Light-Emitting Diodes Fabrication of GaN-based metal-oxide-semiconductor Light-Emitting Diodes operating in ultraviolet spectral region Hybrid organic–inorganic semiconductor-based Light-Emitting Diodes
Journal of Applied Physics Appl. Phys. Lett. Appl. Phys. Lett. J. Vac. Sci. Technol. B Appl. Phys. Lett. Appl. Phys. Lett, 1997Co-Authors: Subhendu Guha, Richard A Haight, Nestor A. Bojarczuk, D. W. KiskerAbstract:We demonstrate that the ability of GaN-based Light-Emitting Diodes to emit in the short-wavelength regime makes possible ''hybrid'' organic–inorganic semiconductor Light-Emitting Diodes that consist of two parts: a GaN-based electroluminescent part and an organic thin-film-based fluorescent part that absorbs the electroluminescence and fluoresces at a longer wavelength resulting in color conversion. We also show that organic films with much improved surface smoothness may be obtained by deposition at reduced temperatures.