Browsing by Subject "Organic light emitting diodes (OLED)"

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    AC-driven, color-and brightness-tunable organic light-emitting diodes constructed from an electron only device
    (2013) Zhao, Y.; Chen, R.; Gao, Y.; Leck, K.S.; Yang X.; Liu, S.; Abiyasa, A.P.; Divayana, Y.; Mutlugun, E.; Tan, S.T.; Sun H.; Demir, Hilmi Volkan; Sun X.W.
    In this paper, a color- and brightness-tunable organic light-emitting diode (OLED) is reported. This OLED was realized by inserting a charge generation layer into an electron only device to form an n-i-p-i-n structure. It is shown that, by changing the polarity of applied voltage, only the p-i-n junction operated under positive bias can emit light and, by applying an AC voltage, emission from both junctions was realized. It is also shown that, by using a combination of blue- and red-emiting layers in two p-i-n junctions, both the color and brightness of the resulting white OLED can be tuned independently by changing the positive and negative amplitudes of the AC voltage. © 2013 Elsevier B.V. All rights reserved.
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    Blue organic light-emitting diodes based on pyrazoline phenyl derivative
    (Elsevier, 2012-01-21) Stakhira, P.; Khomyak, S.; Cherpak, V.; Volyniuk, D.; Simokaitiene, J.; Tomkeviciene, A.; Kukhta, N.A.; Grazulevicius, J.V.; Kukhta, A.V.; Sun, X.W.; Demir, Hilmi Volkan; Hotra, Z.; Voznyak, L.
    The results of an experimental study of the electroluminescent device made of ITO/CuI/2,6-di-tert.-butyl-4-(2,5-diphenyl-3,4-dihydro-2H-pyrazol-3-yl)- phenol (HPhP)/3,6-Di(9-carbazolyl)-9-(2-ethylhexyl) carbazole (TCz1)/Ca:Al with efficacy up to 10.63 cd/A are presented. HPhP provides blue emission with a peak wavelength at 445 nm. The layer of TCz1 acts as an electron-transporting layer. In the framework of density functional theory (DFT) approach the geometry configuration and energy levels of HPhP are found being in a good agreement with spectral and cyclic voltammogram data.
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    An efficient non-Lambertian organic light-emitting diode using imprinted submicron-size zinc oxide pillar arrays
    (AIP, 2013) Liu, S. W.; Wang, J. X.; Divayana, Y.; Dev, K.; Tan S.T.; Demir, Hilmi Volkan; Sun, X. W.
    We report phosphorescent organic light-emitting diodes with a substantially improved light outcoupling efficiency and a wider angular distribution through applying a layer of zinc oxide periodic nanopillar arrays by pattern replication in non-wetting templates technique. The devices exhibited the peak emission intensity at an emission angle of 40° compared to 0° for reference device using bare ITO-glass. The best device showed a peak luminance efficiency of 95.5 ± 1.5 cd/A at 0° emission (external quantum efficiency - EQE of 38.5 ± 0.1%, power efficiency of 127 ± 1 lm/W), compared to that of the reference device, which has a peak luminance efficiency of 68.0 ± 1.4 cd/A (EQE of 22.0 ± 0.1%, power efficiency of 72 ± 1 lm/W). © 2013 American Institute of Physics.