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<front>
<journal-meta>
<journal-id journal-id-type="doi">10.1002/(ISSN)1521-4095</journal-id>
<journal-id journal-id-type="publisher-id">ADMA</journal-id>
<journal-title-group>
<journal-title xml:lang="en">Advanced Materials</journal-title>
<abbrev-journal-title abbrev-type="publisher" xml:lang="en">Adv. Mater.</abbrev-journal-title>
</journal-title-group>
<issn publication-format="ppub">0935-9648</issn>
<issn publication-format="epub">1521-4095</issn>
</journal-meta>
<article-meta>
<article-id pub-id-type="doi">10.1002/adma.202418694</article-id>
<article-id pub-id-type="publisher-id">ADMA202418694</article-id>
<article-categories>
<subj-group subj-group-type="overline" xml:lang="en">
<subject>Research Article</subject>
</subj-group>
<subj-group subj-group-type="heading" xml:lang="en">
<subject>Research Article</subject>
</subj-group>
</article-categories>
<title-group>
<article-title xml:lang="en">Probing Out‐Of‐Plane Charge Transport in Organic Semiconductors Using Conductive Atomic Force Microscopy</article-title>
</title-group>
<contrib-group>
<contrib id="adma202418694-cr-0001" contrib-type="author" corresp="yes">
<name>
<surname>Gicevičius</surname>
<given-names>Mindaugas</given-names>
</name>
<contrib-id contrib-id-type="orcid">https://orcid.org/0000-0003-4773-5568</contrib-id>
<email>mg980@cam.ac.uk</email>
<xref ref-type="corresp" rid="correspondenceTo">*</xref>
<xref ref-type="aff" rid="adma202418694-aff-0001">
<sup>1</sup>
</xref>
</contrib>
<contrib id="adma202418694-cr-0002" contrib-type="author">
<name>
<surname>Gong</surname>
<given-names>Haoxin</given-names>
</name>
<xref ref-type="aff" rid="adma202418694-aff-0001">
<sup>1</sup>
</xref>
</contrib>
<contrib id="adma202418694-cr-0003" contrib-type="author">
<name>
<surname>Turetta</surname>
<given-names>Nicholas</given-names>
</name>
<contrib-id contrib-id-type="orcid">https://orcid.org/0000-0002-4932-5768</contrib-id>
<xref ref-type="aff" rid="adma202418694-aff-0002">
<sup>2</sup>
</xref>
</contrib>
<contrib id="adma202418694-cr-0004" contrib-type="author">
<name>
<surname>Wood</surname>
<given-names>William</given-names>
</name>
<contrib-id contrib-id-type="orcid">https://orcid.org/0000-0003-2451-0614</contrib-id>
<xref ref-type="aff" rid="adma202418694-aff-0001">
<sup>1</sup>
</xref>
</contrib>
<contrib id="adma202418694-cr-0005" contrib-type="author">
<name>
<surname>Volpi</surname>
<given-names>Martina</given-names>
</name>
<xref ref-type="aff" rid="adma202418694-aff-0003">
<sup>3</sup>
</xref>
</contrib>
<contrib id="adma202418694-cr-0006" contrib-type="author">
<name>
<surname>Geerts</surname>
<given-names>Yves</given-names>
</name>
<contrib-id contrib-id-type="orcid">https://orcid.org/0000-0002-2660-5767</contrib-id>
<xref ref-type="aff" rid="adma202418694-aff-0003">
<sup>3</sup>
</xref>
<xref ref-type="aff" rid="adma202418694-aff-0004">
<sup>4</sup>
</xref>
</contrib>
<contrib id="adma202418694-cr-0007" contrib-type="author">
<name>
<surname>Samorì</surname>
<given-names>Paolo</given-names>
</name>
<contrib-id contrib-id-type="orcid">https://orcid.org/0000-0001-6256-8281</contrib-id>
<xref ref-type="aff" rid="adma202418694-aff-0002">
<sup>2</sup>
</xref>
</contrib>
<contrib id="adma202418694-cr-0008" contrib-type="author" corresp="yes">
<name>
<surname>Sirringhaus</surname>
<given-names>Henning</given-names>
</name>
<contrib-id contrib-id-type="orcid">https://orcid.org/0000-0001-9827-6061</contrib-id>
<email>hs220@cam.ac.uk</email>
<xref ref-type="corresp" rid="correspondenceTo">*</xref>
<xref ref-type="aff" rid="adma202418694-aff-0001">
<sup>1</sup>
</xref>
</contrib>
</contrib-group>
<aff id="adma202418694-aff-0001">
<label>
<sup>1</sup>
</label>

<named-content content-type="organisation-division">Cavendish Laboratory</named-content>

<institution>University of Cambridge</institution>

<named-content content-type="street">JJ Thomson Avenue</named-content>
 <city>Cambridge</city>
 <postal-code>CB3 0HE</postal-code>
 <country country="GB">UK</country>

</aff>
<aff id="adma202418694-aff-0002">
<label>
<sup>2</sup>
</label>

<named-content content-type="organisation-division">Université de Strasbourg</named-content>

<named-content content-type="organisation-division">CNRS</named-content>

<institution>ISIS UMR 7006</institution>

<named-content content-type="street">8 allée Gaspard Monge</named-content>
 <city>Strasbourg</city>
 <postal-code>F‐67000</postal-code>
 <country country="FR">France</country>

</aff>
<aff id="adma202418694-aff-0003">
<label>
<sup>3</sup>
</label>

<named-content content-type="organisation-division">Laboratoire de Chimie des Polymères</named-content>

<institution>Université Libre de Bruxelles (ULB)</institution>

<named-content content-type="street">Boulevard du Triomphe, CP 206/01</named-content>
 <city>Bruxelles</city>
 <postal-code>1050</postal-code>
 <country country="BE">Belgium</country>

</aff>
<aff id="adma202418694-aff-0004">
<label>
<sup>4</sup>
</label>

<named-content content-type="organisation-division">International Solvay Institutes of Physics and Chemistry</named-content>

<institution>Université Libre de Bruxelles (ULB)</institution>

<named-content content-type="street">CP 206/01, Boulevard du Triomphe, CP231</named-content>
 <city>Bruxelles</city>
 <postal-code>1050</postal-code>
 <country country="BE">Belgium</country>

</aff>
<author-notes>
<corresp id="correspondenceTo"><label>*</label>E‐mail: <email>mg980@cam.ac.uk</email>; <email>hs220@cam.ac.uk</email><break/></corresp>
</author-notes>
<pub-date date-type="pub" publication-format="electronic"><day>26</day>
<month>12</month>
<year>2024</year>
</pub-date><elocation-id>2418694</elocation-id>
<history>

<date date-type="received">
<day>29</day>
<month>11</month>
<year>2024</year>
</date>

</history>
<permissions>
<copyright-statement content-type="issue-copyright">© 2024 Wiley‐VCH GmbH</copyright-statement>
<copyright-statement content-type="article-copyright">© 2024 The Author(s). Advanced Materials published by Wiley‐VCH GmbH</copyright-statement>
<copyright-year>2024</copyright-year>
<copyright-holder>© 2024 The Author(s). Advanced Materials published by Wiley‐VCH GmbH</copyright-holder>
<license>
<ali:license_ref>http://creativecommons.org/licenses/by/4.0/</ali:license_ref>
<license-p>This is an open access article under the terms of the <ext-link ext-link-type="uri" xlink:href="http://creativecommons.org/licenses/by/4.0/">Creative Commons Attribution</ext-link> License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.</license-p>
</license>
</permissions>
<abstract xml:lang="en" abstract-type="main">
<title>Abstract</title>
<p xml:lang="en">High contact resistance remains the primary obstacle that hinders further advancements of organic semiconductors (OSCs) in electronic circuits. While significant effort has been directed toward lowering the energy barrier at OSC/metal contact interfaces, approaches toward reducing another major contributor to overall contact resistance – the bulk resistance – have been limited to minimizing the thickness of OSC films. However, the out‐of‐plane conductivity of OSCs, a critical aspect of bulk resistance, has largely remained unaddressed. In this study, multi‐layered 2D crystalline, solution‐processed films of the high‐mobility molecular semiconductor 2,9‐dioctylnaphtho[2,3‐b] naphtha[2′,3′:4,5]thieno[2,3‐d]thiophene (C8‐DNTT‐C8) are investigated using conductive‐probe atomic force microscopy (C‐AFM) to evaluate out‐of‐plane charge transport. The findings reveal a linear increase in out‐of‐plane resistance with the number of molecular layers in the film, which is modeled using an equivalent circuit model with multiple tunneling barriers connected in series. Building upon these results, a vertical transfer length method (V‐TLM) is developed, allowing one to determine the out‐of‐plane resistivity of OSC and providing insights into charge transport properties at a single molecule length scale. The V‐TLM approach highlights the potential of C‐AFM for investigating out‐of‐plane charge transport in OSC thin films and holds promise for accelerating the screening of molecules for high‐performance electronic devices.</p>
</abstract>
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<kwd id="adma202418694-kwd-0001">conductive atomic force microscopy</kwd>
<kwd id="adma202418694-kwd-0002">contact resistance</kwd>
<kwd id="adma202418694-kwd-0003">high mobility</kwd>
<kwd id="adma202418694-kwd-0004">organic semiconductors</kwd>
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<institution-wrap>
<institution>Henry Royce Institute</institution>
<institution-id>http://dx.doi.org/10.13039/100016128</institution-id>
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<institution>Cambridge Royce facilities</institution>
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<award-id>EP/P024947/1</award-id>
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<institution>Sir Henry Royce Institute</institution>
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<institution>Belgian National Fund for Scientific Research</institution>
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</front>
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