Alexander J. L. Hofmann, Simon Züfle, Kohei Shimizu, Markus Schmid, Vivien Wessels, Lars Jäger, Stephane Altazin, Keitaro Ikegami, Motiur Rahman Khan, Dieter Neher, Hisao Ishii, Beat Ruhstaller, Wolfgang Brütting
- If not oriented perfectly isotropically, the strong dipole moment of polar organic semiconductor materials such as tris-(8-hydroxyquinolate)aluminum (Alq3) will lead to the buildup of a giant surface potential (GSP) and thus to a macroscopic dielectric polarization of the organic film. Despite this having been a known fact for years, the implications of such high potentials within an organic layer stack have only been studied recently. In this work, the influence of the GSP on hole injection into organic layers is investigated. Therefore, we apply a concept called dipolar doping to devices consisting of the prototypical organic materials N,N′-Di(1-naphthyl)-N,N′-diphenyl-(1,1′-biphenyl)-4,4′-diamine (NPB) as nonpolar host and Alq3 as dipolar dopant with different mixing ratios to tune the GSP. The mixtures are investigated in single-layer monopolar devices as well as bilayer metal/insulator/semiconductor structures. Characterization is done electrically using current-voltage (I-V) characteristics, impedance spectroscopy, and chargeIf not oriented perfectly isotropically, the strong dipole moment of polar organic semiconductor materials such as tris-(8-hydroxyquinolate)aluminum (Alq3) will lead to the buildup of a giant surface potential (GSP) and thus to a macroscopic dielectric polarization of the organic film. Despite this having been a known fact for years, the implications of such high potentials within an organic layer stack have only been studied recently. In this work, the influence of the GSP on hole injection into organic layers is investigated. Therefore, we apply a concept called dipolar doping to devices consisting of the prototypical organic materials N,N′-Di(1-naphthyl)-N,N′-diphenyl-(1,1′-biphenyl)-4,4′-diamine (NPB) as nonpolar host and Alq3 as dipolar dopant with different mixing ratios to tune the GSP. The mixtures are investigated in single-layer monopolar devices as well as bilayer metal/insulator/semiconductor structures. Characterization is done electrically using current-voltage (I-V) characteristics, impedance spectroscopy, and charge extraction by linearly increasing voltage and time of flight, as well as with ultraviolet photoelectron spectroscopy. We find a maximum in device performance for moderate to low doping concentrations of the polar species in the host. The observed behavior can be described on the basis of the Schottky effect for image-force barrier lowering, if the changes in the interface dipole, the carrier mobility, and the GSP induced by dipolar doping are taken into account.…
MetadatenAuthor details: | Alexander J. L. HofmannORCiD, Simon ZüfleORCiD, Kohei ShimizuORCiD, Markus Schmid, Vivien Wessels, Lars Jäger, Stephane Altazin, Keitaro Ikegami, Motiur Rahman KhanORCiD, Dieter NeherORCiDGND, Hisao IshiiORCiD, Beat Ruhstaller, Wolfgang BrüttingORCiD |
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DOI: | https://doi.org/10.1103/PhysRevApplied.12.064052 |
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ISSN: | 2331-7019 |
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Title of parent work (English): | Physical review applied |
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Publisher: | American Physical Society |
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Place of publishing: | College Park |
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Publication type: | Article |
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Language: | English |
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Date of first publication: | 2019/12/24 |
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Publication year: | 2019 |
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Release date: | 2020/05/07 |
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Tag: | Carrier dynamics; Doped semiconductors; Electric polarization; Interfaces; Optoelectronics; Organic LEDs; Organic electronics; Organic semiconductors |
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Volume: | 12 |
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Issue: | 6 |
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Number of pages: | 11 |
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Funding institution: | German Research Foundation (DFG)German Research Foundation (DFG); Swiss National Fonds (SNF)Swiss National Science Foundation (SNSF) [Br 1728/15-1]; DFGGerman Research Foundation (DFG) [Br 1728/20-1]; German Ministry for Education and Research (BMBF)Federal Ministry of Education & Research (BMBF) [13N13664]; Bavarian State Ministry for Science and the Arts through the collaborative research initiative "Solar Technologies Go Hybrid" ("SolTech"); Japan Society for the Promotion of Science (JSPS) via JSPS KAKENHI [JP16H04222, JP18J21921]; JSPS Research Fellowship for Young ScientistsMinistry of Education, Culture, Sports, Science and Technology, Japan (MEXT)Japan Society for the Promotion of Science; JSPS Summer Program; BRIDGE Fellowship |
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Organizational units: | Mathematisch-Naturwissenschaftliche Fakultät / Institut für Physik und Astronomie |
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DDC classification: | 5 Naturwissenschaften und Mathematik / 53 Physik / 530 Physik |
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Peer review: | Referiert |
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