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Thickness-dependent energy-level alignment at the organic–organic interface induced by templated gap states

DOI: 10.1002/admi.202101382 DOI Help

Authors: Jan Hagenlocher (University of Tübingen) , Katharina Broch (University of Tübingen) , Matthias Zwadlo (University of Tübingen) , Daniel Lepple (University of Tübingen) , Jonathan Rawle (Diamond Light Source) , Francesco Carla (Diamond Light Source) , 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: Advanced Materials Interfaces , VOL 133

State: Published (Approved)
Published: December 2021
Diamond Proposal Number(s): 18570

Open Access Open Access

Abstract: Planar organic heterostructures are widely explored and employed in photovoltaic cells, light-emitting diodes, and bilayer field-effect transistors. An important role for device performance plays the energy level alignment at the inorganic–organic and organic–organic interfaces. In this work, incremental ultraviolet photoelectron spectroscopy measurements and real-time X-ray scattering experiments are used to thoroughly investigate the thickness-dependent electronic and structural properties of a perfluoropentacene (PFP)-on-[6]phenacene heterostructure. For both materials an incremental increase of the material work function (positive interface dipole) is found. For [6]phenacene, this can be assigned to a thickness-dependent change of molecular arrangement evident from a change of the unit cell volume and a consequential alteration of the ionization energy. In the case of PFP the interface dipole stems from charge transfer from the substrate into unoccupied molecular orbitals resulting in an electrostatic potential on the surface. The magnitude of this potential can be correlated with an increased gap state density resulting from templated structural defects mediated by the bottom layer.

Journal Keywords: energy-level alignment; gap states; organic semiconductors; structural defects

Diamond Keywords: Semiconductors

Subject Areas: Materials, Physics

Instruments: I07-Surface & interface diffraction

Added On: 27/12/2021 10:24

Adv Materials Inter - 2021 - Hagenlocher - Thickness%E2%80%90Dependent Energy%E2%80%90Level Alignment at the Organic Organic Interface.pdf

Discipline Tags:

Surfaces Hard condensed matter - electronic properties Physics Hard condensed matter - structures Electronics Materials Science interfaces and thin films

Technical Tags:

Diffraction Grazing Incidence X-ray Diffraction (GIXD)