PD Dr. rer. nat. Andreas Opitz

PD Dr. Andreas Opitz erforscht den Ladungstransfer an Grenzflächen zwischen organischen Halbleitern, insbesondere die Bildung und Eigenschaften von Donor-Akzeptor-Komplexen. Sein aktueller Fokus liegt auf der Kontrolle von Kristallstruktur, Molekülorientierung und elektronischen Eigenschaften dieser Materialien durch gezielte Prozessparameter wie Lösungsmittelwahl und Beschichtungsmethoden. Die Erkenntnisse ermöglichen die Optimierung von organischen Optoelektronik-Bauteilen wie Solarzellen und Transistoren, indem die Ladungstransporteigenschaften und Stabilität gezielt verbessert werden. Relevant ist dies für die Halbleiter- und Photovoltaik-Industrie sowie für Anwendungen in organischen Elektronik-Geräten.

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• Ladungstransfer an Heterogrenzflächen organischer Halbleiter

  Quelle ↗

  Förderer: DFG Sachbeihilfe Zeitraum: 03/2014 - 12/2017 Projektleitung: PD Dr. rer. nat. Andreas Opitz

• Ladungstransfer an Heterogrenzflächen organischer Halbleiter: Zu einer einheitlichen Beschreibung von Szenarien im Übergangsbereich zwischen Grundzustand bzw. angeregtem Zustand

  Quelle ↗

  Förderer: DFG Sachbeihilfe Zeitraum: 05/2019 - 05/2024 Projektleitung: PD Dr. rer. nat. Andreas Opitz

• Charge-transfer crystallites as molecular electrical dopants

  2015

  Nature Communications · DOI

  Ground-state integer charge transfer is commonly regarded as the basic mechanism of molecular electrical doping in both, conjugated polymers and oligomers. Here, we demonstrate that fundamentally different processes can occur in the two types of organic semiconductors instead. Using complementary experimental techniques supported by theory, we contrast a polythiophene, where molecular p-doping leads to integer charge transfer reportedly localized to one quaterthiophene backbone segment, to the quaterthiophene oligomer itself. Despite a comparable relative increase in conductivity, we observe only partial charge transfer for the latter. In contrast to the parent polymer, pronounced intermolecular frontier-orbital hybridization of oligomer and dopant in 1:1 mixed-stack co-crystallites leads to the emergence of empty electronic states within the energy gap of the surrounding quaterthiophene matrix. It is their Fermi-Dirac occupation that yields mobile charge carriers and, therefore, the co-crystallites-rather than individual acceptor molecules-should be regarded as the dopants in such systems.

• Doping of Organic Semiconductors: Impact of Dopant Strength and Electronic Coupling

  2013

  Angewandte Chemie International Edition · DOI

  Molecular doping: The standard model for molecular p-doping of organic semiconductors (OSCs) assumes integer charge transfer between OSC and dopant. This is in contrast to an alternative model based on intermolecular complex formation instead. By systematically varying the acceptor strength it was possible to discriminate the two models. The latter is clearly favored, suggesting strategies for the chemical design of more efficient molecular dopants. As a service to our authors and readers, this journal provides supporting information supplied by the authors. Such materials are peer reviewed and may be re-organized for online delivery, but are not copy-edited or typeset. Technical support issues arising from supporting information (other than missing files) should be addressed to the authors. Please note: The publisher is not responsible for the content or functionality of any supporting information supplied by the authors. Any queries (other than missing content) should be directed to the corresponding author for the article.