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On the origin of gap states in molecular semiconductors—a combined UPS, AFM, and X-ray diffraction study
Authors:
Jan
Hagenlocher
(University of Tübingen)
,
Niels
Scheffczyk
(University of Tübingen)
,
Katharina
Broch
(University of Tübingen)
,
Giuliano
Duva
(University of Tübingen)
,
Nadine
Russegger
(University of Tübingen)
,
Lisa
Egenberger
(University of Tübingen)
,
Rupak
Banerjee
(Indian Institute of Technology Gandhinagar)
,
Satoshi
Kera
(Institute for Molecular Science)
,
Frank
Schreiber
(University of Tübingen)
,
Alexander
Hinderhofer
(University of Tübingen)
Co-authored by industrial partner:
No
Type:
Journal Paper
Journal:
The Journal Of Physical Chemistry C
, VOL 10
State:
Published (Approved)
Published:
August 2021
Abstract: Electronic states within the HOMO–LUMO gap of organic semiconductors play a key role in the energy level alignment of substrate–organic and organic–organic interfaces and therefore are a defining parameter for device functionality and efficiency. They are thought to result from structural defects influencing the specific environment of a molecule. Varying the substrate temperature for samples grown by molecular beam deposition, we are able to control their density. Using atomic force microscopy and X-ray scattering techniques, we can differentiate defects depending on their length scale and effective direction. Comparison of the respective defect density with the density of gap states, measured directly via ultra-low-background ultraviolet photoelectron spectroscopy, enables to correlate structural and electronic properties for different prototypical organic semiconductors. We investigate the impact of gap states on the energy level alignment and find a direct link between structural defects and the interface dipole.
Journal Keywords: Carbon nanomaterials; Thin films; Nanospheres; Organic compounds; Defects
Diamond Keywords: Semiconductors; Photovoltaics; Organic Light Emitting Diodes (OLEDs)
Subject Areas:
Materials,
Chemistry,
Physics
Instruments:
I07-Surface & interface diffraction
Other Facilities: SiXS at Soleil
Added On:
09/08/2021 08:32
Discipline Tags:
Surfaces
Earth Sciences & Environment
Sustainable Energy Systems
Energy
Physics
Climate Change
Physical Chemistry
Electronics
Energy Materials
Chemistry
Materials Science
interfaces and thin films
Technical Tags:
Diffraction