Postadsorption Work Function Tuning via Hydrogen Pressure Control

Hermann Edlbauer, Egbert Zojer, Oliver T Hofmann

Publikation: Beitrag in einer FachzeitschriftArtikelForschungBegutachtung

Abstract

The work function of metal substrates can be easily tuned, for instance, by adsorbing layers of molecular electron donors and acceptors. In this work, we discuss the possibility of changing the donor/acceptor mixing ratio reversibly after adsorption by choosing a donor/acceptor pair that is coupled via a redox reaction and that is in equilibrium with a surrounding gas phase. We discuss such a situation for the example of tetrafluoro-1,4-benzenediol (TFBD)/tetrafluoro-1,4-benzoquinone (TFBQ), adsorbed on Cu(111) and Ag(111) surfaces. We use density functional theory and ab initio thermodynamics to show that arbitrary TFBD/TFBQ mixing ratios can be set using hydrogen pressures attainable in low to ultrahigh vacuum. Adjusting the mixing ratio allows modifying the work function over a range of about 1 eV. Finally, we contrast single-species submonolayers with mixed layers to discuss why the resulting inhomogeneities in the electrostatic energy above the surface have different impacts on the interfacial level alignment and the work function.

Originalspracheenglisch
Seiten (von - bis)27162-27172
Seitenumfang11
FachzeitschriftThe journal of physical chemistry (Washington, DC) / C
Jahrgang119
Ausgabenummer48
DOIs
PublikationsstatusVeröffentlicht - 3 Dez 2015

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Pressure control
mixing ratios
Hydrogen
Tuning
tuning
quinones
hydrogen
Redox reactions
Ultrahigh vacuum
ultrahigh vacuum
Density functional theory
Electrostatics
inhomogeneity
Gases
Metals
adjusting
alignment
Thermodynamics
electrostatics
vapor phases

Fields of Expertise

  • Advanced Materials Science

Dies zitieren

Postadsorption Work Function Tuning via Hydrogen Pressure Control. / Edlbauer, Hermann; Zojer, Egbert; Hofmann, Oliver T.

in: The journal of physical chemistry (Washington, DC) / C, Jahrgang 119, Nr. 48, 03.12.2015, S. 27162-27172.

Publikation: Beitrag in einer FachzeitschriftArtikelForschungBegutachtung

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AB - The work function of metal substrates can be easily tuned, for instance, by adsorbing layers of molecular electron donors and acceptors. In this work, we discuss the possibility of changing the donor/acceptor mixing ratio reversibly after adsorption by choosing a donor/acceptor pair that is coupled via a redox reaction and that is in equilibrium with a surrounding gas phase. We discuss such a situation for the example of tetrafluoro-1,4-benzenediol (TFBD)/tetrafluoro-1,4-benzoquinone (TFBQ), adsorbed on Cu(111) and Ag(111) surfaces. We use density functional theory and ab initio thermodynamics to show that arbitrary TFBD/TFBQ mixing ratios can be set using hydrogen pressures attainable in low to ultrahigh vacuum. Adjusting the mixing ratio allows modifying the work function over a range of about 1 eV. Finally, we contrast single-species submonolayers with mixed layers to discuss why the resulting inhomogeneities in the electrostatic energy above the surface have different impacts on the interfacial level alignment and the work function.

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