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Energy Level Alignment in Organic-Organic Heterojunctions: The TTF/TCNQ Interface

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Beltrán Finez, Juan Ignacio and Flores, Fernando and Martínez, José I. and Ortega, José (2013) Energy Level Alignment in Organic-Organic Heterojunctions: The TTF/TCNQ Interface. Journal of physical chemistry C, 117 (8). pp. 3888-3894. ISSN 1932-7447

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Official URL: http://dx.doi.org/10.1021/jp306079t


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http://pubs.acs.org/Publisher


Abstract

The energy level alignment of the two organic materials forming the TTF-TCNQ interface is analyzed by means of a local orbital DFT calculation, including an appropriate correction for the transport energy gaps associated with both materials. These energy gaps are determined by a combination of some experimental data and the results of our calculations for the difference between the TTF_(HOMO) and the TCNQ_(LUMO) levels. We find that the interface is metallic, as predicted by recent experiments, due to the overlap (and charge transfer) between the Density of States corresponding to these two levels, indicating that the main mechanism controlling the TTF-TCNQ energy level alignment is the charge transfer between the two materials. We find an induced interface dipole of 0.7 eV in good agreement with the experimental evidence. We have also analyzed the electronic properties of the TTF-TCNQ interface as a function of an external bias voltage ∆ between the TCNQ and TTF crystals, finding a transition between metallic and insulator behavior for ∆ ∼ 0.5 eV.


Item Type:Article
Additional Information:

© 2013 American Chemical Society. This work is supported by Spanish MICIIN under contract FIS2010-16046, the CAM under contract S2009/MAT-1467 and the European Project MINOTOR (Grant FP7-NMP-228424). JIB gratefully acknowledges financial support by the European Project MINOTOR. JIM acknowledges funding from Spanish MICIIN through Juan de la Cierva Program. Special thanks to Dr. Daniel González for the development of the XEO software package, which has been extensively used for the data analysis.

Uncontrolled Keywords:TTF-TCNQ; Dynamics; Devices; Metal.
Subjects:Sciences > Physics > Electricity
Sciences > Physics > Electronics
ID Code:31357
Deposited On:27 Jul 2015 07:53
Last Modified:10 Dec 2018 14:58

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