Probing nanoscale photo-oxidation in organic films using spatial hole burning near-field scanning optical microscopy

Credo, Grace M.; Lowman, Geoffrey; Dearo, J. A.; Carson, Paul J.; Winn, Darby L.; Buratto, Steven K.

doi:10.1063/1.481391

Cited by 26 publications

(25 citation statements)

References 47 publications

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“…[15] Recently it has been shown for thin organic films that the photooxidation kinetics of a poly(phenylene vinylene) derivative is more than 10 times faster than for Alq 3 . [16] …”

Section: The Effect Of Water Vapormentioning

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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“…[15] Recently it has been shown for thin organic films that the photooxidation kinetics of a poly(phenylene vinylene) derivative is more than 10 times faster than for Alq 3 . [16] …”

Section: The Effect Of Water Vapormentioning

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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show abstract

“…Buratto and co-workers studied the electronic properties of stretch-oriented PPV films using PL 33 and photoconductivity 34,69 NSOM. Credo et al 70 as well as McNeill et al 71 have studied carrier mobility in MEH-PPV films using photo-oxidation and electric-field-modulated PL NSOM, respectively. Teetsov and Vanden Bout used PL NSOM to observe ordered domains in annealed thin films of 9,9-dialkylpolyfluorenes 28,29 that exhibited high polarization ratios.…”

Section: A Background: Spectral Signature Of Interchain Species In Cmentioning

confidence: 99%

Nanoscopic interchain aggregate domain formation in conjugated polymer films studied by third harmonic generation near-field scanning optical microscopy

Schaller

Snee

Johnson

et al. 2002

The Journal of Chemical Physics

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The electronic structure of conjugated polymer films is of current interest due to the wide range of potential applications for such materials in optoelectronic devices. A central outstanding issue is the significance of interchain electronic species in films of these materials. In this paper, we investigate the nature of interchain species in films of poly͓2-methoxy-5-͑2Ј-ethylhexyloxy͒-1,4-phenylene vinylene͔ ͑MEH-PPV͒ both before and after thermal annealing. Our investigation employs a combination of third harmonic generation ͑THG͒ and near-field scanning optical microscopy to measure the wavelength and spatial dependence of the THG efficiency. These chemically selective imaging measurements reveal new, low-energy absorption features in nanometer-scale spatially distinct regions of annealed films that are only infrequently observed prior to annealing. This suggests that the polymer strands in annealed MEH-PPV films pack together closely enough that significant ground-state wave function overlap can occur: thermal annealing creates nanoscopic aggregation domains. THG polarization studies indicate that polymer chain segments in these domains have a preferred orientational alignment. The spatial correlation of these aligned nanoscopic regions within the annealed films suggests that they form via a nucleation and growth type mechanism. In combination with previous work, these data support the idea that the nature and spatial distribution of interchain interactions in conjugated polymer films are complex; conjugated polymer films likely contain an inhomogeneous spatial distribution of both ground-and excited-state interchain species.

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“…The annealing temperature of 140 -C was selected from our AFM observations as discussed below. These results suggest that there is no detectable chemical and structural change among the Alq 3 thin films annealed in O 2 and N 2 , indicating that no tangible thermal oxidation of the Alq 3 thin film in O 2 exists although photo-oxidation has been previously reported under UV light [16,17].…”

Section: Vt-afm Measurements Under O 2 and Nmentioning

confidence: 65%

Visualization of thermally-activated degradation pathways of tris(8-hydroxyquinoline) aluminum thin films for electroluminescence application

2005

Thin Solid Films

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Probing nanoscale photo-oxidation in organic films using spatial hole burning near-field scanning optical microscopy

Cited by 26 publications

References 47 publications

Water Vapor and Oxygen Degradation Mechanisms in Organic Light Emitting Diodes

Water Vapor and Oxygen Degradation Mechanisms in Organic Light Emitting Diodes

Nanoscopic interchain aggregate domain formation in conjugated polymer films studied by third harmonic generation near-field scanning optical microscopy

Visualization of thermally-activated degradation pathways of tris(8-hydroxyquinoline) aluminum thin films for electroluminescence application

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