2018-Sustainable Industrial Processing Summit
SIPS2018
Volume 6. New and Advanced Materials and Technologies
| Editors: | F. Kongoli, F. Marquis, P. Chen, T. Prikhna, N. Chikhradze |
| Publisher: | Flogen Star OUTREACH |
| Publication Year: | 2018 |
| Pages: | 392 pages |
| ISBN: | 978-1-987820-92-8 |
| ISSN: | 2291-1227 (Metals and Materials Processing in a Clean Environment Series) |
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A Concept of Embedded Dipole in Interfacial Engineering and its Applications in Organic Electronics
Michael Zharnikov1;1HEIDELBERG UNIVERSITY, Heidelberg, Germany;
Type of Paper: Invited
Id Paper: 75
Topic: 43
Abstract:
The energy level alignment between the metal electrodes and adjacent organic semiconductor, as well as between the buffer layers and adjacent electrode/active layer is a key issue in organic electronics and photovoltaics. A frequently used approach in this context is the introduction of a suitable interfacial dipole by modification of the electrodes/buffer layers with a self-assembled monolayer (SAM). For this purpose, SAMs are usually decorated with a specific dipolar terminal group, attached to the molecular backbone, which, however, can affect the growth of organic semiconductor and be easily modified itself, thus distorting the desirable energy level alignment. An alternative novel concept involves embedding of a dipolar functional group into the backbone of the SAM constituents, thus decoupling dipole control and interfacial chemistry [1,2]. The validity of this concept is demonstrated by the example of several model SAMs, containing embedded dipolar groups with different chemical compositions and orientations. Combining molecules with oppositely oriented dipolar groups in a mixed SAM allows continuous variation of the interfacial dipole in a broad range, enabling its exact adaptation to the requirements of a particular device. Using a specific spectroscopic signature of the embedded groups, within the concept of electrostatic shift, the morphology of the mixed films can be precisely monitored down to the molecular scale by X-ray photoemission spectroscopy [3,4]. As an example of potential usefulness of this novel class of SAMs in organic electronics and photovoltaics, their application in organic field-effect transistors is demonstrated, resulting in decrease of the contact resistance by ca. three orders of magnitude accompanied by significant improvement in the performance and stability of the devices. As a continuation of these activities, application of novel dipolar SAMs in organic solar cells is now under consideration [5].
Keywords:
Nanomaterials; New and advanced materials; New and advanced technology;References:
[1] T. Abu-Husein, S. Schuster, D. A. Egger, M. Kind, T. Santowski, A. Wiesner, R. Chiechi, E. Zojer, A. Terfort, M. Zharnikov, Adv. Funct. Mater. 25 (2015) 3943-3957.[2] O. M. Cabarcos, S. Schuster, I. Hehn, P. P. Zhang, M. M. Maitani, N. Sullivan, J.-B. Giguère, J.-F. Morin, P. S. Weiss, E. Zojer, M. Zharnikov, D. L. Allara, J. Phys. Chem. C 121 (2017) 15815-15830.
[3] T. C. Taucher, I. Hehn, O. T. Hofmann, M. Zharnikov, E. Zojer, J. Phys. Chem. C 120, (2016) 3428-3437.
[4] I. Hehn, S. Schuster, T. Wachter, T. Abu-Husein, A. Terfort, M. Zharnikov, E. Zojer, J. Phys. Chem. Lett. 7 (2016) 2994-3000.
[5] Q. Zhang, W.-T. Wang, C.-Yu Chi, T. Wachter, J.-W. Chen, C.-Yi Tsai,Y.-C. Huang, M. Zharnikov, Y. Tai, and D.-J. Liaw, Energy Environ. Sci. 11 (2018) 682-691.