Polymorphism in the 1:1 Charge‐Transfer Complex DBTTF–TCNQ and Its Effects on Optical and Electronic Properties
Abstract
The organic charge‐transfer complex dibenzotetrathiafulvalene–7,7,8,8‐tetracyanoquinodimethane is found to crystallize in two polymorphs when grown by physical vapor transport: the known α‐polymorph and a new structure, the β‐polymorph. Structural and elemental analysis via selected area electron diffraction, X‐ray photoelectron spectroscopy, and polarized IR spectroscopy reveal that the complexes have the same stoichiometry with a 1:1 donor: acceptor ratio, but exhibit unique unit cells. The structural variations result in significant differences in the optoelectronic properties of the crystals, as observed in the experiments and electronic‐structure calculations. Raman spectroscopy shows that the α‐polymorph has a degree of charge transfer of about 0.5e, while the β‐polymorph is nearly neutral. Organic field‐effect transistors fabricated on these crystals reveal that in the same device structure both polymorphs show ambipolar charge transport, but the α‐polymorph exhibits electron‐dominant transport while the β‐polymorph is hole‐dominant. Together, these measurements imply that the transport features result from differing donor–acceptor overlap and consequential varying in frontier molecular orbital mixing, as suggested theoretically for charge‐transfer complexes.
Document Details
- Document Type
- Pub Defense Publication
- Publication Date
- Sep 14, 2016
- Source ID
- 10.1002/aelm.201600203
Entities
People
- Christina A Hacker
- Curt A. Richter
- Jihua Chen
- Jun'ya Tsutsumi
- Katelyn P. Goetz
- Nathan S. Corbin
- Oana D. Jurchescu
- Rakesh K. Behera
- Sujitra Pookpanratana
- Tatsuo Hasegawa
- Veaceslav Coropceanu
Organizations
- Georgia Tech
- National Institute of Advanced Industrial Science and Technology
- National Institute of Standards and Technology
- National Science Foundation
- Oak Ridge National Laboratory
- United States Army Research Laboratory
- University of Tokyo
- Wake Forest University