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.

scholarly journals Light-Emission and Electricity-Generation Properties of Photovoltaic Organic Light-Emitting Diodes with Rubrene/DBP Light-Emission and Electron-Donating Layers

2014 ◽  
Vol 2014 ◽  
pp. 1-6 ◽  
Author(s):  
Mun Soo Choi ◽  
Ho-Nyeon Lee
Keyword(s):  
Power Conversion Efficiency ◽  
Conversion Efficiency ◽  
Fill Factor ◽  
Light Emitting Diodes ◽  
Light Emission ◽  
Power Conversion ◽  
Organic Light Emitting Diodes ◽  
Light Emitting ◽  
Emission Efficiency ◽  
Organic Light

We report the dependence of the characteristics of photovoltaic organic light-emitting diodes (PVOLEDs) on the composition of the light-emission and electron-donating layer (EL-EDL). 5,6,11,12-Tetraphenylnaphthacene (rubrene): dibenzo{[f,f′]-4,4′,7,7′-tetraphenyl}diindeno[1,2,3-cd:1′,2′,3′-lm]perylene (DBP) was used to form the EL-EDL, and C60was used as an electron-accepting layer (EAL) material. A half-gap junction was formed at the EAL/EL-EDL interface. As the rubrene ratio in the EL-EDL increased, the emission spectra became blue-shifted and the light-emission efficiency increased. The highest emission efficiency was achieved with an EL-EDL composed of 95% rubrene and 5% DBP. The short-circuit current decreased as the rubrene content increased up to 50% and then saturated, while the open-circuit voltage was almost unchanged regardless of the rubrene content. The power-conversion efficiency and fill factor increased as the composition of the EL-EDL approached that of pure materials. By controlling the rubrene : DBP ratio, the emission color could be adjusted. The emission efficiency of devices with mixed rubrene/DBP EL-EDLs could be greater than that of either pure rubrene or pure DBP devices. We obtained an overall power-conversion efficiency of 3% and a fill factor greater than 50%.

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.

scholarly journals Organic Light Emitting Diodes for White Light Emission

10.5772/9892 ◽  
2010 ◽  
Author(s):  
Ritu Srivastava ◽  
M.N. Kamalasanan ◽  
Gayatri Chauhan ◽  
Arunandan Kumar ◽  
Priyanka Tyagi ◽  
...  
Keyword(s):  
White Light ◽  
Light Emitting Diodes ◽  
Light Emission ◽  
White Light Emission ◽  
Organic Light Emitting Diodes ◽  
Light Emitting ◽  
Organic Light

scholarly journals Highly Isotactic Poly(N-butenyl-carbazole): Synthesis, Characterization, and Optical Properties

2016 ◽  
Vol 2016 ◽  
pp. 1-8 ◽  
Author(s):  
Antonio Botta ◽  
Vincenzo Venditto ◽  
Alfredo Rubino ◽  
Stefania Pragliola
Keyword(s):  
Optical Properties ◽  
Fluorescence Spectra ◽  
Light Emission ◽  
Organic Light Emitting Diodes ◽  
X Ray Diffraction ◽  
Light Emitting ◽  
X Ray ◽  
Organic Light ◽  
Optical Applications ◽  
Carbazole Group

The synthesis of isotactic poly(N-butenyl-carbazole) (i-PBK) by using homogeneous isospecific Ziegler-Natta catalytic system is reported. The achieved polymer is crystalline and shows, to DSC and X-ray analysis, two distinct crystalline phases.i-PBK FTIR spectrum and X-ray diffraction pattern are compared with those of poly(N-vinylcarbazole) (PVK). The observed differences are tentatively associated with higher flexibility of thei-PBK chains due to the alkylene group connecting the carbazole group to the main chain.i-PBK optical properties are also compared with those of PVK and isotactic poly(N-pentenyl-carbazole) (i-PPK), a higher homologue ofi-PBK recently used as emitting layer in organic light emitting diodes (OLEDs) showing white light emission. The close similarity of the fluorescence spectra ofi-PBK andi-PPK is a promising basis for optical applications of this polymer.

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