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Title: Prototypical Organic–Oxide Interface: Intramolecular Resolution of Sexiphenyl on In 2O 3 (111)

The performance of an organic semiconductor device is critically determined by the geometric alignment, orientation, and ordering of the organic molecules. Although an organic multilayer eventually adopts the crystal structure of the organic material, the alignment and configuration at the interface with the substrate/electrode material are essential for charge injection into the organic layer. This work focuses on the prototypical organic semiconductor para-sexiphenyl (6P) adsorbed on In 2O 3(111), the thermodynamically most stable surface of the material that the most common transparent conducting oxide, indium tin oxide, is based on. The onset of nucleation and formation of the first monolayer are followed with atomically resolved scanning tunneling microscopy and noncontact atomic force microscopy (nc-AFM). Annealing to 200 °C provides sufficient thermal energy for the molecules to orient themselves along the high-symmetry directions of the surface, leading to a single adsorption site. The AFM data suggests an essentially planar adsorption geometry. With increasing coverage, the 6P molecules first form a loose network with a poor long-range order. Eventually, the molecules reorient into an ordered monolayer. In conclusion, this first monolayer has a densely packed, well-ordered (2 × 1) structure with one 6P per In 2O 3(111) substrate unit cell, that is,more » a molecular density of 5.64 × 10 13 cm –2.« less
ORCiD logo [1] ;  [1] ; ORCiD logo [1] ; ORCiD logo [2] ;  [1] ; ORCiD logo [1]
  1. TU Wien, Vienna (Austria)
  2. Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
Publication Date:
Grant/Contract Number:
Published Article
Journal Name:
ACS Applied Materials and Interfaces
Additional Journal Information:
Journal Volume: 10; Journal Issue: 16; Journal ID: ISSN 1944-8244
American Chemical Society (ACS)
Research Org:
Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
Sponsoring Org:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22)
Country of Publication:
United States
36 MATERIALS SCIENCE; adsorption site; atomic force microscopy; indium oxide; monolayer; organic molecules; scanning tunneling microscopy; sexiphenyl
OSTI Identifier:
Alternate Identifier(s):
OSTI ID: 1437896