Oxadiazole-metal interface: from isolated molecules to pi-stacking.
Derivatives of 2,5-diaryl-1,3,4-oxadiazole are used widely for electron transport in organic light emitting diodes (OLED). This study addresses the structure of 2,5-diphenyl-1,3,4-oxadiazole (PPD) molecules on Cu(111) using scanning tunneling microscopy (STM) and density function theory (DFT): at incomplete coverage, PPD molecules are found horizontally on the surface; once the surface area is insufficient to accommodate all adsorbates in this fashion, a pi-stacked film of vertically arranged molecules is formed. In contrast to bulk PPD, in this film, the molecules are arranged face-to-face at a separation of square root(3a0) = 4.4 A as imposed by the substrate interatomic spacing along the [-2 1 1] direction.
Kwon
Ki-Young
KY
Pierce Hall, University of California-Riverside, Riverside, California 92521, USA. ki-young.kwon@email.ucr.edu
Lin
Xing
X
Pawin
Greg
G
Wong
Kin
K
Bartels
Ludwig
L