TU Darmstadt / ULB / TUbiblio

Electric potential distributions in space charge regions of molecular organic adsorbates using a simplified distributed states model

Mankel, Eric and Hein, Corinna and Kühn, Maybritt and Mayer, Thomas (2014):
Electric potential distributions in space charge regions of molecular organic adsorbates using a simplified distributed states model.
In: physica status solidi (a), 211 (9), WILEY-VCH Verlag GmbH & Co. KGaA, pp. 2040-2048, ISSN 18626300,
[Online-Edition: http://dx.doi.org/10.1002/pssa.201330432],
[Article]

Abstract

We study the evolution of the electric surface potential for small molecular organic semiconductors adsorbed on different high-work function substrates using photoelectron spectroscopy. Usually, the surface potential of these materials shows a typical progression in dependence of the adsorbate layer thickness indicating the formation of a space charge region near the interface. We discuss the surface potential evolution on the basis of the commonly used Schottky model and a second model using a density of states distribution (DOS) in the adsorbed semiconductor energy gap. In order to derive an analytical solution, we simplify an existing approach for space charge regions at polymer contacts. This approach is based on tailing gap states in polymer adsorbates. We simplify it using a constant DOS distribution. The differences between the Schottky model and the simplified distributed states model will be discussed. Finally, both models are applied to measured values of the surface potential evolution of some exemplary organic molecules on different substrates. We find that the surface potential evolution of the simplified distributed states model describes the measured potential development more accurately than the Schottky model. The DOS is estimated in the framework of the model being between 1018 and 1019 cm−3 eV−1.

Item Type: Article
Erschienen: 2014
Creators: Mankel, Eric and Hein, Corinna and Kühn, Maybritt and Mayer, Thomas
Title: Electric potential distributions in space charge regions of molecular organic adsorbates using a simplified distributed states model
Language: English
Abstract:

We study the evolution of the electric surface potential for small molecular organic semiconductors adsorbed on different high-work function substrates using photoelectron spectroscopy. Usually, the surface potential of these materials shows a typical progression in dependence of the adsorbate layer thickness indicating the formation of a space charge region near the interface. We discuss the surface potential evolution on the basis of the commonly used Schottky model and a second model using a density of states distribution (DOS) in the adsorbed semiconductor energy gap. In order to derive an analytical solution, we simplify an existing approach for space charge regions at polymer contacts. This approach is based on tailing gap states in polymer adsorbates. We simplify it using a constant DOS distribution. The differences between the Schottky model and the simplified distributed states model will be discussed. Finally, both models are applied to measured values of the surface potential evolution of some exemplary organic molecules on different substrates. We find that the surface potential evolution of the simplified distributed states model describes the measured potential development more accurately than the Schottky model. The DOS is estimated in the framework of the model being between 1018 and 1019 cm−3 eV−1.

Journal or Publication Title: physica status solidi (a)
Volume: 211
Number: 9
Publisher: WILEY-VCH Verlag GmbH & Co. KGaA
Uncontrolled Keywords: organic semiconductors, photoelectron spectroscopy, Schottky model, space charge regions, surface potential
Divisions: 11 Department of Materials and Earth Sciences > Material Science > Electronic Materials
11 Department of Materials and Earth Sciences > Material Science > Surface Science
11 Department of Materials and Earth Sciences > Material Science
11 Department of Materials and Earth Sciences
Date Deposited: 26 Feb 2015 10:22
Official URL: http://dx.doi.org/10.1002/pssa.201330432
Identification Number: doi:10.1002/pssa.201330432
Funders: Financial support from the German Ministry of Education and Research (BMBF) within the MESOMERIE (FKZ 13N10721) and the OPEG 2010 (FKZ 13N9714) projects is gratefully acknowledged.
Export:
Suche nach Titel in: TUfind oder in Google
Send an inquiry Send an inquiry

Options (only for editors)

View Item View Item