| AVS 61st International Symposium & Exhibition | |
| Energy Frontiers Focus Topic | Wednesday Sessions |
| Session EN+AS+EM-WeA |
| Session: | Organic-Inorganic Interfaces for Energy |
| Presenter: | Hyuk-Jae Jang, NIST & WFU |
| Authors: | H.-J. Jang, NIST & WFU S.J. Pookpanratana, NIST A.N. Brigeman, Wake Forest University R.J. Kline, NIST J.I. Basham, NIST & PSU D.J. Gundlach, NIST C.A. Hacker, NIST O.A. Kirillova, NIST O.D. Jurchescu, Wake Forest University C.A. Richter, NIST |
| Correspondent: | Click to Email |
Magnetic field effects (MFEs) in non-magnetic organic semiconductors provide a non-contact approach to control electronic and optoelectronic properties of organic-based devices by using a sub-tesla magnetic field and thus they have been of great interest to industry as well as academia around the world.1,2 However, there is no consensus on the physical mechanism(s) causing the MFEs in organic semiconductors even though a variety of fundamental models have been proposed to explain the effects.2 Studies on many different organic semiconductors and organic-based structures have shown that the magnitude and even the sign of the MFEs can vary by changing the measurement and fabrication conditions such as bias voltage, film thickness, and temperature. Therefore, it is suggested that there can be multiple origins inducing the MFEs and the outcome may result from a competition between different MFE mechanisms.2
In this presentation, we report a novel method of manipulating the MFEs on electrical resistance of organic semiconductors, namely organic magnetoresistance in Alq3 (tris-(8-hydroxyquinoline) aluminum) – based devices by simply adding a molecular self-assembled monolayer (SAM) between a metal electrode and an organic semiconductor. SAMs have been known for their versatile use in various technological applications.3 Particularly, SAMs can alter the physical property of an inorganic solid surface and thus modify the interface between an electrode and an organic thin film when a SAM is inserted between them.3 We show for the first time that the interfacial modification by simply inserting a fluorinated SAM ( heptadecafluoro-1-decanethiol [CF3(CF2)7(CH2)2SH] or F-SAM) in organic-based devices changes the sign of organic magnetoresistance due to the change in relative strength of different MFE mechanisms coexisting in organic-based devices. In addition, we utilize different MFE mechanisms coexisting in organic-based devices by adding a thin TPD (N,N′-Bis(3-methylphenyl)-N,N′-diphenylbenzidine) layer to create a system whose organic magnetoresistance can be tuned by an external bias voltage.
References
1. J. Kalinowski, M. Cocchi, D. Virgili, P. Di Marco, and V. Fattori, Chem. Phys. Lett. vol. 380, pp. 710-715, 2003.
2. W. Wagemans, P. Janssen, A. J. Schellekens, F. L. Bloom, P. A. Bobbert, and B. Koopmans, SPIN vol. 1, pp. 93-108, 2011.
3. J. C. Love, L. A. Estroff, J. K. Kriebel, R. G. Nuzzo, and G. M. Whitesides, Chem. Rev. vol. 105, pp. 1103-1169, 2005.