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Oligothiophene‐Based Phosphonates for Surface Modification of Ultraflat Transparent Conductive Oxides
Author(s) -
Timpel Melanie,
Nardi Marco V.,
Wegner Berthold,
Ligorio Giovanni,
Pasquali Luca,
Hildebrandt Jana,
Pätzel Michael,
Hecht Stefan,
Ohta Hiromichi,
Koch Norbert
Publication year - 2020
Publication title -
advanced materials interfaces
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.671
H-Index - 65
ISSN - 2196-7350
DOI - 10.1002/admi.201902114
Subject(s) - materials science , indium tin oxide , molecule , substrate (aquarium) , dipole , work function , chemical physics , transparent conducting film , oxide , nanotechnology , thin film , layer (electronics) , organic chemistry , chemistry , oceanography , geology , metallurgy
The self‐assembly of electroactive organic molecules on transparent conductive oxides is a versatile strategy to engineer the interfacial energy‐level alignment and to enhance charge carrier injection in optoelectronic devices. Via chemical grafting of an aromatic oligothiophene molecule by changing the position of the phosphonic acid anchoring group with respect to the organic moiety (terminal and internal), the direction of the main molecular dipole is changed, i.e., from parallel to perpendicular to the substrate, to study the molecular arrangement and electronic properties at the organic–inorganic interface. It is found that the observed work function increase cannot solely be predicted based on the calculated molecular dipole moment of the oligothiophene‐based phosphonates. In addition, charge transfer from the substrate to the molecule has to be taken into account. Molecular assembly and induced electronic changes are analogous for both indium‐tin oxide (ITO) and zinc oxide (ZnO), demonstrating the generality of the approach and highlighting the direct correlation between molecular coverage and electronic effects.