Pronounced polarization-induced energy level shifts at boundaries of organic semiconductor nanostructures

Katherine A Cochrane, Agustin Eduardo Schiffrin, Tanya S Roussy, Martina Capsoni, Sarah A Burke

Research output: Contribution to journalArticleResearchpeer-review

Abstract

Organic semiconductor devices rely on the movement of charge at and near interfaces, making an understanding of energy level alignment at these boundaries an essential element of optimizing materials for electronic and optoelectronic applications. Here we employ low temperature scanning tunneling microscopy and spectroscopy to investigate a model system: two-dimensional nanostructures of the prototypical organic semiconductor, PTCDA (3,4,9,10-perylenetetracarboxylic dianhydride) adsorbed on NaCl (2 ML)/Ag(111). Pixel-by-pixel scanning tunneling spectroscopy allows mapping of occupied and unoccupied electronic states across these nanoislands with sub-molecular spatial resolution, revealing strong electronic differences between molecules at the edges and those in the centre, with energy level shifts of up to 400 meV. We attribute this to the change in electrostatic environment at the boundaries of clusters, namely via polarization of neighbouring molecules. The observation of these strong shifts illustrates a crucial issue: interfacial energy level alignment can differ substantially from the bulk electronic structure in organic materials
Original languageEnglish
Pages (from-to)1-8
Number of pages8
JournalNature Communications
Volume6
DOIs
Publication statusPublished - 2015

Cite this

Cochrane, Katherine A ; Schiffrin, Agustin Eduardo ; Roussy, Tanya S ; Capsoni, Martina ; Burke, Sarah A. / Pronounced polarization-induced energy level shifts at boundaries of organic semiconductor nanostructures. In: Nature Communications. 2015 ; Vol. 6. pp. 1-8.
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abstract = "Organic semiconductor devices rely on the movement of charge at and near interfaces, making an understanding of energy level alignment at these boundaries an essential element of optimizing materials for electronic and optoelectronic applications. Here we employ low temperature scanning tunneling microscopy and spectroscopy to investigate a model system: two-dimensional nanostructures of the prototypical organic semiconductor, PTCDA (3,4,9,10-perylenetetracarboxylic dianhydride) adsorbed on NaCl (2 ML)/Ag(111). Pixel-by-pixel scanning tunneling spectroscopy allows mapping of occupied and unoccupied electronic states across these nanoislands with sub-molecular spatial resolution, revealing strong electronic differences between molecules at the edges and those in the centre, with energy level shifts of up to 400 meV. We attribute this to the change in electrostatic environment at the boundaries of clusters, namely via polarization of neighbouring molecules. The observation of these strong shifts illustrates a crucial issue: interfacial energy level alignment can differ substantially from the bulk electronic structure in organic materials",
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Pronounced polarization-induced energy level shifts at boundaries of organic semiconductor nanostructures. / Cochrane, Katherine A; Schiffrin, Agustin Eduardo; Roussy, Tanya S; Capsoni, Martina; Burke, Sarah A.

In: Nature Communications, Vol. 6, 2015, p. 1-8.

Research output: Contribution to journalArticleResearchpeer-review

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T1 - Pronounced polarization-induced energy level shifts at boundaries of organic semiconductor nanostructures

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AU - Schiffrin, Agustin Eduardo

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AU - Burke, Sarah A

PY - 2015

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AB - Organic semiconductor devices rely on the movement of charge at and near interfaces, making an understanding of energy level alignment at these boundaries an essential element of optimizing materials for electronic and optoelectronic applications. Here we employ low temperature scanning tunneling microscopy and spectroscopy to investigate a model system: two-dimensional nanostructures of the prototypical organic semiconductor, PTCDA (3,4,9,10-perylenetetracarboxylic dianhydride) adsorbed on NaCl (2 ML)/Ag(111). Pixel-by-pixel scanning tunneling spectroscopy allows mapping of occupied and unoccupied electronic states across these nanoislands with sub-molecular spatial resolution, revealing strong electronic differences between molecules at the edges and those in the centre, with energy level shifts of up to 400 meV. We attribute this to the change in electrostatic environment at the boundaries of clusters, namely via polarization of neighbouring molecules. The observation of these strong shifts illustrates a crucial issue: interfacial energy level alignment can differ substantially from the bulk electronic structure in organic materials

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