Thermal Stabilities of Organic Layer in Electroluminescent Devices

Do, Lee‐Mi; Han, Eun‐Mi; Yamamoto, Naokatsu; Fujihira, M.

doi:10.1080/10587259608040358

Cited by 15 publications

(6 citation statements)

References 7 publications

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“…[2] However, the environmental stability and reliability of the devices is still a major problem. Degradation has been attributed to various mechanisms, including crystallization of the organic solids, [3,4] electrochemical reactions at the electrode/organic interface, [5] migration of ionic species, [6] and electrochemical reactions. [7] Cathode oxidation and cathode delamination were shown to be largely responsible for the growth of non-emissive spots on the emitting device area.…”

Section: Introductionmentioning

confidence: 99%

Water Vapor and Oxygen Degradation Mechanisms in Organic Light Emitting Diodes

Schaer

Nüesch²,

Berner³

et al. 2001

Adv. Funct. Mater.

347

118

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The degradation of organic light emitting diodes (OLEDs) due to the growth of dark spots can be attributed to the synergy of three external causes: dust particles deposited during the fabrication process, pollution by water vapor, and pollution by oxygen. On the basis of a set of new experiments performed on benchmark devices, we demonstrate that, for a given distribution of dust particles and a given concentration of the polluting agent, water is a thousand times more destructive than oxygen at room temperature. While the thermal diffusion of oxygen causes the oxidation of both the metal at the interface and the dye in the bulk of the device, water acts by an electrochemical process causing the delamination of the electrode.

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Section: Introductionmentioning

confidence: 99%

Water Vapor and Oxygen Degradation Mechanisms in Organic Light Emitting Diodes

Schaer

Nüesch²,

Berner³

et al. 2001

Adv. Funct. Mater.

347

118

View full text Add to dashboard Cite

show abstract

“…Numerous causes of device degradation have been proposed in the literature, including the delamination of electrodes,7 cathode oxidation,8 electrochemical reactions at electrode/organic interfaces,9 hydrolysis of the metallo-quinolate layer,10 and an intrinsic instability of the metallo-quinolate cation.11 Device failure has also been attributed to crystallization of the active layers, especially the hole transport layer. 12 Despite the importance of the archetype hole transport molecule NPB, relatively few studies of its fundamental molec-¤ Electronic Supplementary Information available. See http : // www.rsc.org/suppdata/cp/b1/b101619i/ ular properties have appeared in the literature.…”

Section: Introductionmentioning

confidence: 99%

Structure and infrared (IR) assignments for the OLED material: N,N′-diphenyl-N,N′-bis(1-naphthyl)-1,1′-biphenyl-4,4″-diamine (NPB)

Halls

Tripp

Schlegel

2001

Phys. Chem. Chem. Phys.

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“…Recrystallization of an amorphous film, for example, may lead to cracking or delamination, with catastrophic consequences for the device. 4,5 Understanding the local structure of amorphous films of organic semiconductors, and its evolution with device operation, is of fundamental importance to organic electronics. Unfortunately, very little is known about the local structure in such amorphous films.…”

mentioning

confidence: 99%

Observation of intermediate-range order in a nominally amorphous molecular semiconductor film

et al. 2007

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Synchrotron X-ray diffraction from a nominally amorphous molecular semiconductor film reveals both the presence of intermediate-range order (IRO) corresponding to crystalline domains with an average size of a few nanometres, and the growth of these domains upon exposure of the film to moisture.Due to a high demand for better, more efficient, and less expensive displays and lighting, the science and engineering community has concentrated efforts on the development, understanding and optimization of new electroluminescent materials. Consequently, organic light emitting devices (OLEDs) have gained interest as an alternative to inorganic semiconductor technology. 1,2 Not surprisingly, device performance is strongly correlated to the microstructure of the organic thin films. While perfect singlecrystalline films promise the best transport properties and quantum efficiencies, they are very difficult to deposit over large areas. Amorphous films have been found to perform significantly better than most polycrystalline films. The high surface roughness associated with the latter is problematic in sandwich-type structures. Moreover, grain boundaries in polycrystalline materials may provide trapping and recombination centres, which can degrade device performance and lifetime. In contrast, the hoppingtype conductivity in amorphous films is adequate for several applications, including OLEDs and organic photovoltaics. 1 As a result, the development of amorphous molecular materials is of great interest. 3 Changes in the film structure that occur during device operation are also of interest, as the structural integrity of the film affects device performance. Recrystallization of an amorphous film, for example, may lead to cracking or delamination, with catastrophic consequences for the device. 4,5 Understanding the local structure of amorphous films of organic semiconductors, and its evolution with device operation, is of fundamental importance to organic electronics. Unfortunately, very little is known about the local structure in such amorphous films. This is due to the fact that amorphous materials are relatively poor scatterers, so that standard X-ray scattering from thin films is very hard to obtain with lab-based X-ray generators. Furthermore, in device-relevant configurations, where the film thickness is of the order of 100 nm, scattering from the substrate can be pronounced and can obscure the faint scattering signatures from the film itself. Both problems can be overcome using synchrotron-based grazing incidence scattering methods, as we will demonstrate below. In this communication we investigate the microstructure of the ruthenium complex [Ru(bpy) 3 ] 2+ (PF 6

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Thermal Stabilities of Organic Layer in Electroluminescent Devices

Cited by 15 publications

References 7 publications

Water Vapor and Oxygen Degradation Mechanisms in Organic Light Emitting Diodes

Water Vapor and Oxygen Degradation Mechanisms in Organic Light Emitting Diodes

Structure and infrared (IR) assignments for the OLED material: N,N′-diphenyl-N,N′-bis(1-naphthyl)-1,1′-biphenyl-4,4″-diamine (NPB)

Observation of intermediate-range order in a nominally amorphous molecular semiconductor film

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