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991.
Jin Sung Kang Ju-An Yoon Seung Il Yoo Jin Wook Kim Bo Mi Lee Hyeong Hwa Yu C.-B.Moon Woo Young Kim 《中国光学快报(英文版)》2015,(3):76-79
In this Letter, blue phosphorescence organic light-emitting diodes(PHOLEDs) employ structures for electron and/or hole confinement; 1,3,5-tris(N-phenylbenzimiazole-2-yl)benzene is used as a hole confinement layer and tris-(phenylpyrazole)iridium [IreppzT3] is utilized for an electron confinement layer(ECL). The electrical and optical properties of the fabricated blue PHOLEDs with various carrier-confinement structures are analyzed.Structures with a large energy offset between the carrier confinement and emitting layers enhance the charge-carrier balance in the emitting region, resulting from the effective carrier confinement. The maximum external quantum efficiency of the blue PHOLEDs with the double-ECLs is 24.02% at 1500 cd∕m2and its luminous efficiency is 43.76 cd∕A, which is 70.47% improved compared to the device without a carrier-confinement layer. 相似文献
992.
How To Reach Intense Luminescence for Compounds Capable of Excited‐State Intramolecular Proton Transfer?
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Kamil Skonieczny Jaeduk Yoo Jillian M. Larsen Eli M. Espinoza Michał Barbasiewicz Prof. Valentine I. Vullev Prof. Chang‐Hee Lee Prof. Daniel T. Gryko 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(22):7485-7496
Photoinduced intramolecular direct arylation allows structurally unique compounds containing phenanthro[9′,10′:4,5]imidazo[1,2‐f]phenanthridine and imidazo[1,2‐f]phenanthridine skeletons, which mediate excited‐state intramolecular proton transfer (ESIPT), to be efficiently synthesized. The developed polycyclic aromatics demonstrate that the combination of five‐membered ring structures with a rigid arrangement between a proton donor and a proton acceptor provides a means for attaining large fluorescence quantum yields, exceeding 0.5, even in protic solvents. Steady‐state and time‐resolved UV/Vis spectroscopy reveals that, upon photoexcitation, the prepared protic heteroaromatics undergo ESIPT, converting them efficiently into their excited‐state keto tautomers, which have lifetimes ranging from about 5 to 10 ns. The rigidity of their structures, which suppresses nonradiative decay pathways, is believed to be the underlying reason for the nanosecond lifetimes of these singlet excited states and the observed high fluorescence quantum yields. Hydrogen bonding with protic solvents does not interfere with the excited‐state dynamics and, as a result, there is no difference between the occurrences of ESIPT processes in MeOH versus cyclohexane. Acidic media has a more dramatic effect on suppressing ESIPT by protonating the proton acceptor. As a result, in the presence of an acid, a larger proportion of the fluorescence of ESIPT‐capable compounds originates from their enol excited states. 相似文献
993.
Dongwon Yoo Jeeyun Song Moon Sung Kang Eun-Sil Kang Young Gyu Kim 《Tetrahedron: Asymmetry》2011,22(16-17):1700-1704
A stereodivergent approach employing an N-hydroxymethyl group has been utilized to produce both diastereomeric derivatives of (3S,4S)-AHPPA 3 and (3R,4S)-AHPPA 4, via an intramolecular conjugate addition and an intramolecular epoxidation, respectively. The selectivity of the intramolecular conjugate addition was more than 10:1 while that of the intramolecular epoxidation was more than 1:20. 相似文献
994.
A non-Markovian kinetic equation for a system of two identical interacting two-level atoms has been derived. The solution
to this equation has been used for calculating the shape of spectral lines of this system. 相似文献
995.
Chang Suk Kong Wan Suk Yoo Na Gyeong Jo Han Seong Kim 《Journal of Macromolecular Science: Physics》2013,52(1):122-131
Electrospinning provides a straightforward method to produce polymer fibers with nanoscale diameters. Although the setup for electrospinning is simple and convenient, the spinning mechanism itself is quite complicated. A complete understanding of this mechanism remains to be elucidated and the factors that govern fiber formation are not well understood. In this study, we investigate the electrospinning instabilities by observing the electrospinning jet behaviors with various photographic exposure times ranging from 1/100 to 1/10,000 of a second and the corresponding fiber depositions. We propose an electrospinning mechanism responsible for producing nanoscale fibers and their deposition patterns. 相似文献
996.
E. D. Mishina S. V. Semin K. V. Shvyrkov A. V. Kudryavtsev N. A. Il’in N. E. Sherstyuk V. M. Mukhortov 《Physics of the Solid State》2012,54(5):887-893
The specific features of the application of two-photon microscopy and spectroscopy to the investigation of multiferroic and piezoelectric nanostructures have been considered. It has been shown that the nonlinear optical response of planar multilayer barium strontium titanate/bismuth ferrite nanostructures is characterized by local electrically induced and magnetically induced contributions in specific spectral ranges. For peptide piezoelectric bio-microtubes, it has been found that the maximum value of the second harmonic generation intensity does not change along the tube, whereas the direction of polarization changes significantly. 相似文献
997.
998.
Young Ju Kim Ji Sub Hwang Young Joon Yoo Bui Xuan Khuyen Xianfeng Chen YoungPak Lee 《Current Applied Physics》2017,17(10):1260-1263
The single resonator generally reveals a single absorption band, and the resonators with different sizes or shapes have to be arranged in order to achieve multi-absorption bands. We propose the triple-band metamaterial absorber by utilizing only single resonator. Meta-atoms are made of the toothed-wheel shape metallic pattern and a continuous metallic plane, separated by a dielectric layer. The first and the third absorption bands are induced by the fundamental and the third-harmonic magnetic resonances, respectively, and the second absorption band is induced by the magnetic resonance relevant to two grooves. In addition, the diffraction peak appears between the second and the third absorption bands, due to the surface currents which are separated between the upper and the lower metallic pattern parts. The proposed structure is scalable to smaller size for the infrared and the visible regimes. 相似文献
999.
1000.