Characterization of light-erasable giant surface potential built up in evaporated Alq3 thin films

Sugi, Keiji; Ishii, Hisao; Kimura, Yasuo; Niwano, Michio; Ito, Eisuke; Washizu, Y.; Hayashi, Naoki; Ouchi, Yukio; Seki, Kazuhiko

doi:10.1016/j.tsf.2004.06.035

Cited by 47 publications

(42 citation statements)

References 4 publications

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“…More generally, it needs to be stated that molecules that possess permanent dipoles can result in energy level shifts at organic/organic heterojunctions, as well as also within an individual layer as function of thickness [79].…”

Section: Molecular Dipoles For Energy Level Tuningmentioning

confidence: 99%

Electronic structure of interfaces with conjugated organic materials

Koch

2012

Physica Rapid Research Ltrs

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The function and efficiency of most organic electronic and opto‐electronic devices greatly depend on the electronic structure of the interfaces therein. Charge injection from electrical contacts into the organic semiconductor, charge extraction, or exciton dissociation at organic semiconductor heterojunctions are crucial processes that must be optimized for high device efficiency. Consequently, the energy levels at these interfaces must be matched to allow for optimal performance. The key mechanisms that determine the energy level alignment at organic/electrode and organic/organic interfaces are reviewed, and methods to adjust the levels at such interfaces are presented. (© 2012 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

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Section: Molecular Dipoles For Energy Level Tuningmentioning

confidence: 99%

Electronic structure of interfaces with conjugated organic materials

Koch

2012

Physica Rapid Research Ltrs

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“…Light shielding is required to observe the gSPs of Alq 3 because the gSPs are vanished out by photoexposure. 7,8 We investigated the characteristics of the photoinduced gSP reduction and clarified the fact that the drift of photoexcited carriers in thin Alq 3 films cancels out the gSPs. 9-11 Most drifted carriers recombine; however, the rest are captured by traps, especially by those existing at the surface/interfaces, where no countercarriers are found.…”

mentioning

confidence: 99%

Photoinduced evolution of surface-potential undulation observed on vacuum-deposited thin films of tris(8-hydroxyquinolinato) aluminum

Ozasa

Ito

Maeda

et al. 2011

Applied Physics Letters

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We investigated surface-potential (SP) undulation on thin films of tris(8-hydroxyquinolinato) aluminum (Alq3) using Kelvin probe force microscopy with intermittent photoexposure. SP undulation with a cloudlike morphology of 200–300 nm in lateral size was observed for Alq3 films of 10–200 nm in thickness. A short photoexposure increased the SP undulation approximately twice as that of the unexposed values, while the SP average decreased monotonically. We analyzed the origin of the SP undulation and the mechanism of its photoenhancement based on its morphology, film thickness dependence, and photoexposure dependence. We suggested nonuniform distributions of mobility and charged traps.

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“…More interestingly, GSP is reduced by irradiation of visible light. Two hypotheses have been proposed so far: photoinduced randomization of molecular orientation [6] and electrostatic screening by photogenerated carrier [7]. By means of first-order electroabsorption (EA) measurement, we have demonstrated that an Alq 3 thin film presents noncentrosymmetric molecular orientation even after GSP reduction by light irradiation, suggesting that photocarrier hypothesis is more plausible for the GSP reduction mechanism.…”

Section: Introductionmentioning

confidence: 82%

Long-Term Relaxation of Molecular Orientation in Vacuum-Deposited ALQ₃Thin Films

Isoshima

Ito

et al. 2009

Molecular Crystals and Liquid Crystals

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Long-term measurement of noncentrosymmetric molecular orientation of vacuum-evaporated tris(8-hydroxyquinolinato) aluminum (III) (Alq 3 ) thin film was performed by means of first-order electroabsorption (EA) spectroscopy. This molecular orientation is responsible for the giant surface potential of Alq 3 film, and it might be utilized to nonlinear optical devices. Although the EA response presented reduction, the relaxation time constant was on the order of year. Possible mechanisms for the reduction are discussed.

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Characterization of light-erasable giant surface potential built up in evaporated Alq3 thin films

Cited by 47 publications

References 4 publications

Electronic structure of interfaces with conjugated organic materials

Electronic structure of interfaces with conjugated organic materials

Photoinduced evolution of surface-potential undulation observed on vacuum-deposited thin films of tris(8-hydroxyquinolinato) aluminum

Long-Term Relaxation of Molecular Orientation in Vacuum-Deposited ALQ₃Thin Films

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Characterization of light-erasable giant surface potential built up in evaporated Alq3 thin films

Cited by 47 publications

References 4 publications

Electronic structure of interfaces with conjugated organic materials

Electronic structure of interfaces with conjugated organic materials

Photoinduced evolution of surface-potential undulation observed on vacuum-deposited thin films of tris(8-hydroxyquinolinato) aluminum

Long-Term Relaxation of Molecular Orientation in Vacuum-Deposited ALQ3Thin Films

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Long-Term Relaxation of Molecular Orientation in Vacuum-Deposited ALQ₃Thin Films