Interface Behaviour and Work Function Modification of Self-Assembled Monolayers on Sn-Doped In2O3
Department of Materials and Earth Sciences, Technische Universität Darmstadt, Otto-Berndt-Straße 3, 64287 Darmstadt, Germany
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Received: 11 March 2019 / Accepted: 25 March 2019 / Published: 29 March 2019
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The modification of the work function of Sn-doped In2
(ITO) by vacuum adsorption of 4-(Dimethylamino)benzoic acid (4-DMABA) has been studied using in situ photoelectron spectroscopy. Adsorption of 4-DMABA is self-limited with an approximate thickness of a single monolayer. The lowest work function obtained is
eV, enabling electron injection into many organic materials. In order to identify a potential influence of the ITO substrate surface on the final work function, different ITO surface orientations and treatments have been applied. Despite the expected differences in substrate work function and chemical bonding of 4-DMABA to the substrate, no influence of substrate surface orientation is identified. The resulting work function of ITO/4-DMABA substrates can be described by a constant ionization potential of the adsorbed 4-DMABA of
eV, a constant band alignment between ITO and 4-DMABA and a varying Fermi energy in the ITO substrate. This corresponds to the behaviour of a conventional semiconductor heterostructure and deviates from the vacuum level alignment of interfaces between organic compounds. The difference is likely related to a stronger chemical bonding at the ITO/4-DMABA interface compared to the van der Waals bonding at interfaces between organic compounds.
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Hubmann, A.H.; Dietz, D.; Brötz, J.; Klein, A. Interface Behaviour and Work Function Modification of Self-Assembled Monolayers on Sn-Doped In2O3. Surfaces 2019, 2, 241-256.
Hubmann AH, Dietz D, Brötz J, Klein A. Interface Behaviour and Work Function Modification of Self-Assembled Monolayers on Sn-Doped In2O3. Surfaces. 2019; 2(2):241-256.
Hubmann, Andreas H.; Dietz, Dominik; Brötz, Joachim; Klein, Andreas. 2019. "Interface Behaviour and Work Function Modification of Self-Assembled Monolayers on Sn-Doped In2O3." Surfaces 2, no. 2: 241-256.
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