Surface States and Adsorbate‐Induced Electronic Structure

Fauster, Thomas; Petek, Hrvoje; Wolf, Martin

doi:10.1002/9783527646463.ch3

Cited by 4 publications

(4 citation statements)

References 93 publications

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“…The observed substantial reduction of the ZnO work function by ∆Φ = −2.9 eV is currently, to our knowledge, only exceeded by adsorption of alkali atoms on various surfaces [128,129,130] and could not, so far, be reached by other organic molecules. This uniqueness of the pyridine molecule results from the concurrence of three advantageous properties that cooperate in reducing the work function [10]:…”

Section: Giant Work Function Reduction At the Pyridine/zno(1010) Intementioning

confidence: 77%

Global and local aspects of the surface potential landscape for energy level alignment at organic-ZnO interfaces

Stähler

Rinke

2017

Chemical Physics

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Hybrid systems of organic and inorganic semiconductors are a promising route for the development of novel opto-electronic and light-harvesting devices. A key ingredient for achieving a superior functionality by means of a hybrid system is the right relative position of energy levels at the interfaces of the two material classes. In this Perspective , we address the sensitivity of the potential energy landscape at various ZnO surfaces, a key ingredient for interfacial energy level alignment, by combining one- and two-photon photoelectron spectroscopy with density-functional theory calculations (DFT). We show that even very large work function changes (>> 2.5 eV) do not necessarily have to be accompanied by surface band bending in ZnO. Band bending – if it does occur – may be localized to few Åor extend over hundreds of nanometers with very different results for the surface work function and energy level alignment. Managing the delicate balance of different interface manipulation mechanisms in organic-inorganic hybrid systems will be a major challenge towards future applications

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Section: Giant Work Function Reduction At the Pyridine/zno(1010) Intementioning

confidence: 77%

Global and local aspects of the surface potential landscape for energy level alignment at organic-ZnO interfaces

Stähler

Rinke

2017

Chemical Physics

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“…One approach to circumvent these issues is two-photon photoelectron (2PPE) spectroscopy using ultrashort laser pulses. This technique allows the determination of absolute binding energies of occupied and unoccupied states of the system [18,19]. For instance, 2PPE spectroscopy has been successfully used to explore the electronic structure of metalsemiconductor, metal-organic and semiconductor-organic interfaces [20][21][22][23][24][25][26][27][28].…”

Section: Introductionmentioning

confidence: 99%

Uncovering the (un-)occupied electronic structure of a buried hybrid interface

Vempati

Deinert

Gierster

et al. 2019

J. Phys.: Condens. Matter

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The energy level alignment at organic/inorganic (o/i) semiconductor interfaces is crucial for any light-emitting or -harvesting functionality. Essential is the access to both occupied and unoccupied electronic states directly at the interface, which is often deeply buried underneath thick organic films and challenging to characterize. We use several complementary experimental techniques to determine the electronic structure of p-quinquephenyl pyridine (5P-Py) adsorbed on ZnO(10-10).The parent anchoring group, pyridine, significantly lowers the work function by up to 2.9 eV and causes an occupied in-gap state (IGS) directly below the Fermi level EF. Adsorption of uprightstanding 5P-Py also leads to a strong work function reduction of up to 2.1 eV and to a similar IGS.The latter is then used as an initial state for the transient population of three normally unoccupied molecular levels through optical excitation and, due to its localization right at the o/i interface, provides interfacial sensitivity, even for thick 5P-Py films. We observe two final states above the vacuum level and one bound state at around 2 eV above EF, which we attribute to the 5P-Py LUMO.By the separate study of anchoring group and organic dye combined with the exploitation of the occupied IGS for selective interfacial photoexcitation this work provides a new pathway for characterizing the electronic structure at buried o/i interfaces.

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“…Experimentally observed image states localize typically 10 to 100 Bohr radii above the surface with lifetimes that may extend to several ps [3]. Studying the dynamics of these states via time-resolved two-photon photoemission spectroscopy has led to an improved understanding of scattering processes occurring at surfaces [7].…”

Section: Introductionmentioning

confidence: 99%

Highly excited electronic image states of metallic nanorings

Fey

Jabusch

Knörzer

et al. 2017

The Journal of Chemical Physics

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We study electronic image states around a metallic nanoring and show that the interplay between the attractive polarization force and a repulsive centrifugal force gives rise to Rydberg-like image states trapped several nanometers away from the surface. The nanoring is modeled as a perfectly conducting isolated torus whose electrostatic image potential is derived analytically. The image states are computed via a two-dimensional finite-difference scheme as solutions of the effective Schrödinger equation describing the outer electron subject to this image potential. These findings demonstrate not only the existence of detached image states around nanorings but allow us also to provide general criteria on the ring geometry, i.e. the aspect ratio of the torus, that need to be fulfilled in order to support such states.

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Surface States and Adsorbate‐Induced Electronic Structure

Cited by 4 publications

References 93 publications

Global and local aspects of the surface potential landscape for energy level alignment at organic-ZnO interfaces

Global and local aspects of the surface potential landscape for energy level alignment at organic-ZnO interfaces

Uncovering the (un-)occupied electronic structure of a buried hybrid interface

Highly excited electronic image states of metallic nanorings

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