Dresden 2011 – wissenschaftliches Programm

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O: Fachverband Oberflächenphysik

O 6: Semiconductor substrates: Adsorption

O 6.6: Vortrag

Montag, 14. März 2011, 12:30–12:45, WIL B122

First-principles study of the organic/ZnO (0001)-O interface: the role of van der Waals interactions — •Yong Xu, Patrick Rinke, Oliver Hofmann, and Matthias Scheffler — Fritz-Haber-Institut der Max-Planck-Gesellschaft, Berlin, Germany

Hybrid inorganic/organic materials have opened up new opportunities for the development of optoelectronics, benefiting from the potential to combine the best features of two distinct material classes. The understanding of their interfacial properties is of critical importance to develop new basic concepts for optoelectronic devices or to optimize device designs. In this work, we studied the interface between the ZnO (0001)-O surface and a prototypical organic acceptor 2,3,5,6-tetrafluoro-7,7,8,8-tetracyanoquinodimethane (F4TCNQ) by first-principles approaches implemented in the FHI-aims code, focusing on the effects of van der Waals (vdW) interactions. We applied and compared various methods to treat vdW interactions, including the non-local Langreth-Lundqvist exchange-correlation functional, exact-exchange plus correlation in the random phase approximation (RPA), and the C₆[n]/R⁶ correction approach by Tkatchenko and Scheffler. While F4TCNQ binds strongly to the clean ZnO (0001)-Zn surface density-functional theory (DFT) with the PBE exchange-correlation funtional gives only weak physical adsorption on the ZnO (0001)-O surface. VdW corrections pull the molecule closer to the surface and considerably enhance the binding energy, emphasizing the importance of vdW interactions for this material class.