Electroluminescence observation of nanoscale phase separation in quaternary AlInGaN light-emitting diodes

2010 ◽  
Vol 96 (15) ◽  
pp. 151109 ◽  
Author(s):  
X. A. Cao ◽  
Y. Yang
Keyword(s):  
Phase Separation ◽  
Light Emitting Diodes ◽  
Light Emitting ◽  
Nanoscale Phase Separation

scholarly journals ToF-SIMS imaging of the nanoscale phase separation in polymeric light emitting diodes: Effect of nanostructure on device efficiency

The Analyst ◽  
2011 ◽  
Vol 136 (4) ◽  
pp. 716-723 ◽  
Author(s):  
Bang-Ying Yu ◽  
Che-Hung Kuo ◽  
Wei-Ben Wang ◽  
Guo-Ji Yen ◽  
Shin-ichi Iida ◽  
...  
Keyword(s):  
Phase Separation ◽  
Light Emitting Diodes ◽  
Light Emitting ◽  
Nanoscale Phase Separation ◽  
Tof Sims ◽  
Device Efficiency

Surface-Directed Phase Separation of Conjugated Polymer Blends for Efficient Light-Emitting Diodes

2008 ◽  
Vol 18 (19) ◽  
pp. 2897-2904 ◽  
Author(s):  
Keng-Hoong Yim ◽  
Zijian Zheng ◽  
Richard H. Friend ◽  
Wilhelm T. S. Huck ◽  
Ji-Seon Kim
Keyword(s):  
Phase Separation ◽  
Polymer Blends ◽  
Conjugated Polymer ◽  
Light Emitting Diodes ◽  
Light Emitting

Improving the Crystallization Resistance of Aluminum(III) 8-Hydroxyquinoline-Based Emitting Materials by Entropic Stabilization

1999 ◽  
Vol 561 ◽  
Author(s):  
Keith A. Higginson ◽  
Baocheng Yang ◽  
Fotios Papadimitrakopoulos
Keyword(s):  
Phase Separation ◽  
Light Emitting Diodes ◽  
Thermally Stable ◽  
Morphological Stability ◽  
X Ray Diffraction ◽  
Light Emitting ◽  
X Ray ◽  
Show Evidence ◽  
Entropic Stabilization

ABSTRACTThe morphological stability of evaporated films of aluminum(III) 8-hydroxyquinoline (Alq3) was investigated. Films which were found to be non-crystalline by x-ray diffraction upon deposition, crystallized rapidly upon annealing, especially where defects were present. Blends of Alq3with aluminum(III) 5-methyl-8-hydroxyquinoline were proposed for thermally stable amorphous emitting layers in light-emitting diodes. Films coevaporated at a 1:1 ratio did not show evidence of crystallization or phase separation even after long annealing periods at temperatures as high as 160°C.

Injecting Inter-Layers and the Built-in Potential of Blue Polymer Light-Emitting Diodes

2000 ◽  
Vol 660 ◽  
Author(s):  
Thomas M. Brown ◽  
Ian S. Millard ◽  
David J. Lacey ◽  
Jeremy H. Burroughes ◽  
Richard H. Friend ◽  
...  
Keyword(s):  
Indium Tin Oxide ◽  
Light Emitting Diodes ◽  
Basic Structure ◽  
Thin Layers ◽  
Carrier Injection ◽  
Semiconducting Polymer ◽  
Light Emitting ◽  
Physical Mechanisms ◽  
Organic Solid ◽  
Polymer Light Emitting Diodes

ABSTRACTThe semiconducting-polymer/injecting-electrode heterojunction plays a crucial part in the operation of organic solid state devices. In polymer light-emitting diodes (LEDs), a common fundamental structure employed is Indium-Tin-Oxide/Polymer/Al. However, in order to fabricate efficient devices, alterations to this basic structure have to be carried out. The insertion of thin layers, between the electrodes and the emitting polymer, has been shown to greatly enhance LED performance, although the physical mechanisms underlying this effect remain unclear. Here, we use electro-absorption measurements of the built-in potential to monitor shifts in the barrier height at the electrode/polymer interface. We demonstrate that the main advantage brought about by inter-layers, such as poly(ethylenedioxythiophene)/poly(styrene sulphonic acid) (PEDOT:PSS) at the anode and Ca, LiF and CsF at the cathode, is a marked reduction of the barrier to carrier injection. The electro- absorption results also correlate with the electroluminescent characteristics of the LEDs.

Low-Temperature Operation of Green, Blue and UV InGaN/GaN Multiple-Quantum-Well Light-Emitting Diodes

2003 ◽  
Vol 764 ◽  
Author(s):  
X. A. Cao ◽  
S. F. LeBoeuf ◽  
J. L. Garrett ◽  
A. Ebong ◽  
L. B. Rowland ◽  
...  
Keyword(s):  
Quantum Well ◽  
Light Emitting Diodes ◽  
Multiple Quantum Well ◽  
Light Output ◽  
Localized States ◽  
Multiple Quantum ◽  
Nonradiative Recombination ◽  
Light Emitting ◽  
Temperature Range ◽  
Green Leds

Absract:Temperature-dependent electroluminescence (EL) of InGaN/GaN multiple-quantum-well light-emitting diodes (LEDs) with peak emission energies ranging from 2.3 eV (green) to 3.3 eV (UV) has been studied over a wide temperature range (5-300 K). As the temperature is decreased from 300 K to 150 K, the EL intensity increases in all devices due to reduced nonradiative recombination and improved carrier confinement. However, LED operation at lower temperatures (150-5 K) is a strong function of In ratio in the active layer. For the green LEDs, emission intensity increases monotonically in the whole temperature range, while for the blue and UV LEDs, a remarkable decrease of the light output was observed, accompanied by a large redshift of the peak energy. The discrepancy can be attributed to various amounts of localization states caused by In composition fluctuation in the QW active regions. Based on a rate equation analysis, we find that the densities of the localized states in the green LEDs are more than two orders of magnitude higher than that in the UV LED. The large number of localized states in the green LEDs are crucial to maintain high-efficiency carrier capture at low temperatures.

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