Spin-Orbital Coupling Effects on Magnetoresistance in Organic Light-Emitting Diodes

2006 ◽  
Vol 965 ◽  
Author(s):  
Bin Hu ◽  
Yue Wu
Keyword(s):  
Reverse Bias ◽  
Metal Electrode ◽  
Organic Light Emitting Diodes ◽  
Capture Zone ◽  
Electron Hole ◽  
Spin Orbital ◽  
Light Emitting ◽  
Hole Capture ◽  
Organic Light ◽  
Spin Orbital Coupling

ABSTRACTThe magnetoresistance of conjugated polymer poly [2-methoxy-5-(2'-ethylhexyloxy)-1,4-phenylenevinylene] (MEH-PPV) based organic light-emitting diodes (OLED) was investigated at both forward and reverse bias at liquid nitrogen temperature. We find that the reverse bias yields a largely increased magnetoresistance when the electron-hole capture zone is away from the metal electrode as compared to the forward bias with the electron-hole capture zone close to the metal electrode. The electroluminescence suggests that the deposited metal atoms enhance the spin-orbital coupling at the polymer/metal interface and consequently lead to electron-hole capture zone-dependent magnetic field effects in organic semiconductor devices.

Degradation in iTMC OLEDs

2007 ◽  
Vol 1029 ◽  
Author(s):  
Leonard J. Soltzberg ◽  
Velda Goldberg ◽  
Michael D. Kaplan ◽  
Heather Bankowski ◽  
Shannon Browne ◽  
...  
Keyword(s):  
Transition Metal Complex ◽  
Light Emission ◽  
Local Heating ◽  
Degradation Process ◽  
Metal Electrode ◽  
Organic Light Emitting Diodes ◽  
Light Emitting ◽  
Organic Light ◽  
Ionic Transition ◽  
Device Operation

AbstractThe processes underlying degradation of organic light emitting diodes (OLEDs) are gradually becoming understood. In ruthenium-based ionic transition metal complex (iTMC) OLEDs, a dimeric species forms during device operation that quenches light emission [1]. Water has been implicated in this degradation process [2]. We report recent studies on degradation of OLEDs fabricated with Ir(ppy)2(dtb-bpy)PF6 [ppy = 2-phenylpyridine, dtb-bpy = 4,4'-di-tert-butyl 2,2'-bipyridine [3]. We have found that applying a thicker-than-usual metal electrode results in shorter turn-on times and higher light emission, though little improvement in lifetime. It appears that the degradation of these devices occurs by a different mechanism from that of the ruthenium-based devices and may involve local heating leading to chemical decomposition of the organic material.Observation of recurring but often transient dark-colored substances in both the Ru(bpy)3(PF6)2 and Ir(ppy)2(dtb-bpy)PF6 systems, seen both in the solid state and in solution samples, may also be indicative of decomposition.

Effect of the electric field during annealing of organic light emitting diodes for improving its on/off ratio

2016 ◽  
Vol 18 (4) ◽  
pp. 2747-2755 ◽  
Author(s):  
Rahul K. Sharma ◽  
Monica Katiyar ◽  
I. V. Kameshwar Rao ◽  
K. N. Narayanan Unni ◽  
Deepak Deepak
Keyword(s):  
Electric Field ◽  
Reverse Bias ◽  
Light Emitting Diodes ◽  
Organic Light Emitting Diodes ◽  
Light Emitting ◽  
Organic Light ◽  
Fast Cooling

(i) The OLED as fabricated (standard). (ii) An OLED annealed, fast cooling, no reverse bias. (iii) As in (ii) except reverse bias during annealing, but not cooling. (iv) As in (iii) with reverse bias also during cooling. (v) As in (iii), except that cooling is slower. (vi) As in (iv), except that cooling is slower.

Study on the Rubrene Emission Sensitized by a Phosphorescent Ir Compound in the Host of CBP

2011 ◽  
Vol 110-116 ◽  
pp. 4512-4517
Author(s):  
Deng Hui Xu ◽  
Xiong Li
Keyword(s):  
Energy Transfer ◽  
Luminous Efficiency ◽  
Organic Light Emitting Diodes ◽  
Device Performance ◽  
Electron Hole ◽  
Light Emitting ◽  
Organic Light ◽  
Bound Electron ◽  
Sensitization Effect ◽  
Triplet Excitons

To obtain the maximum luminous efficiency from an organic material, it is necessary to harness both the spin-symmetric and anti-symmetric molecular excitations (bound electron–hole pairs, or excitons) that result from electrical pumping. Here, we demonstrate that this deficiency can be overcome by using a phosphorescent sensitizer to excite a fluorescent dye. The photoluminescence and sensitization effect between tris (2-phenylpyridine) iridium (Ir (ppy) 3) and 5,6,11,12-tetraphenylnaphthacene (rubrene) in the host of 4,4'-N,N-dicarbazole-biphenyl (CBP) were investigated. The energy transfer characteristics in the electroluminescent process of the system of CBP, Ir (ppy) 3 and Rubrene has been discuss in this article. The Ir (ppy) 3 sensitizer affords an effective way to improve the device performance. In the organic light-emitting diodes based on the Ir (ppy) 3, rubrene and CBP system, both the singlet and triplet excitons can be used.

scholarly journals Oxygen Plasma Treatment of Rear Multilayered Graphene: A Potential Top Electrode for Transparent Organic Light-Emitting Diodes

Materials ◽  
2021 ◽  
Vol 14 (21) ◽  
pp. 6652
Author(s):  
Jong Tae Lim
Keyword(s):  
Plasma Treatment ◽  
Transfer Process ◽  
Oxygen Plasma ◽  
Light Emitting Diodes ◽  
Metal Electrode ◽  
Organic Light Emitting Diodes ◽  
Oxygen Plasma Treatment ◽  
Physical Damage ◽  
Light Emitting ◽  
Organic Light

One of the core technologies of transparent organic light-emitting diodes (TOLEDs) is to develop an optically transparent and high electrical conductivity electrode so that light generated inside the device can efficiently escape into the air through the electrodes. We recently reported in TOLED research that two flipping processes are required to dry-transfer the front multilayered graphene (MLG) to the top electrode, while the rear MLG requires one dry transfer process. As the transfer process increases, the electrical properties of graphene deteriorate due to physical damage and contamination by impurities. At the charge-injecting layer/MLG interface constituting the TOLED, the rear MLG electrode has significantly lower charge injection characteristics than the front MLG electrode, so it is very important to improve the electrical characteristics of the rear MLG. In this paper, we report that the light-emitting properties of the TOLED are improved when an oxygen plasma-treated rear MLG is used as the top electrode, as compared with untreated rear MLG. In addition, the fabricated device exhibits a transmittance of 74–75% at the maximum electroluminescence wavelength, and the uniformity of transmittance and reflectance is more constant at a wavelength of 400–700 nm than in a device with a metal electrode. Finally, near-edge X-ray absorption fine structure spectroscopic analysis proves that the MLG crystallinity is improved with the removal of impurities on the surface after oxygen plasma treatment.

Sign in / Sign up

Export Citation Format

Share Document