Exploiting collective electrostatic effects for the design of interfaces in organic electronics and in porous framework materials

Seminar Announcement

Pic: TU Graz

📅 Tuesday, July 11, 2023 4:15 pm
📌 MIBE Lecture Hall (Room E.126), Boltzmannstraße 11, 85748 Garching

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“Exploiting collective electrostatic effects for the design of interfaces in organic electronics and in porous framework materials”

Prof. Dr. Egbert Zojer
Graz University of Technology

Abstract:

Collective electrostatic effects arise from the periodic assembly of polar entities. They enable the tuning of the electronic properties of, for example, electrode interfaces or of the inner surfaces of porous materials. A common approach for controlling injection barriers at interfaces between metal electrodes and organic semiconductors is the use of polar self-assembled monolayers (SAMs). In this context, a particularly promising strategy is to embed the dipoles within the backbones of the SAM-forming molecules.2,3,4 Employing such embedded-dipole SAMs not only decouples work-function tuning from semiconductor growth, but also allows generating a variety of fundamental insights of how polar layers modify interface properties:1,4 One can, for example, show that core-level spectroscopy not only provides information on the chemical environment of certain atoms, but also serves as a tool for probing the local electrostatic situation at a surface.5 By tuning the interfacial level alignment, embedded dipoles can also modify the transition-voltage in monolayer transport experiments,6 or change contact resistances in organic transistors by several orders of magnitude.7 Besides that, the inclusion of embedded dipole linkers also has considerable potential for controlling the electronic properties of other materials classes: for example, it could be used for inducing potential gradients in porous materials like metal-organic frameworks.8,9 Moreover, exploiting the collective action of polar substituents included in the pore walls of covalent framework materials (COFs) can be employed for tuning the electrostatic energy within their pores10 with the potential of massively impacting the application of COFs in batteries or as catalysts.
1. E. Zojer et al., Adv. Mater. Interfaces 2019, 1900581; 2. T. Abu-Husein et al., Adv. Funct. Mater. 2015, 25, 3943; 3. O. M. Cabarcos et al. J. Phys. Chem. C 2017, 121, 15815.; 4. E. Zojer et al. Acc. Chem. Res. 2022, 55, 13, 1857; 5. T. Taucher et al., J. Phys. Chem. C 2016, 120, 3428; 6. A. Kovalchuk et al., Chem. Sci. 2016, 7, 781. 7. A. Petritz et al., Adv. Funct. Mater. 2018, 28, 1804462.; 8. G. Nascimbeni, et al. Nanomaterials 2020, 10, 2420; 9. A. Nefedov et al., Adv. Mater. 2021, 33, 2103287; 10. E. Zojer, Nano Lett. 2023, 23, 8, 3558–3564.