Skip to main content

Lund University Publications

LUND UNIVERSITY LIBRARIES

Two-Dimensional Crystals as a Buffer Layer for High Work Function Applications : The Case of Monolayer MoO3

Kowalczyk, Dorota A. ; Rogala, MacIej ; Szałowski, Karol ; Belić, Domagoj LU ; Dąbrowski, Paweł ; Krukowski, Paweł ; Lutsyk, Iaroslav ; Piskorski, Michał ; Nadolska, Aleksandra and Krempiński, Patryk , et al. (2022) In ACS Applied Materials and Interfaces 14(39). p.44506-44515
Abstract

We propose that the crystallinity of two-dimensional (2D) materials is a crucial factor for achieving highly effective work function (WF) modification. A crystalline 2D MoO3 monolayer enhances substrate WF up to 6.4 eV for thicknesses as low as 0.7 nm. Such a high WF makes 2D MoO3 a great candidate for tuning properties of anode materials and for the future design of organic electronic devices, where accurate evaluation of the WF is crucial. We provide a detailed investigation of WF of 2D α-MoO3 directly grown on highly ordered pyrolytic graphite, by means of Kelvin probe force microscopy (KPFM) and ultraviolet photoemission spectroscopy (UPS). This study underlines the importance of a controlled environment and the resulting... (More)

We propose that the crystallinity of two-dimensional (2D) materials is a crucial factor for achieving highly effective work function (WF) modification. A crystalline 2D MoO3 monolayer enhances substrate WF up to 6.4 eV for thicknesses as low as 0.7 nm. Such a high WF makes 2D MoO3 a great candidate for tuning properties of anode materials and for the future design of organic electronic devices, where accurate evaluation of the WF is crucial. We provide a detailed investigation of WF of 2D α-MoO3 directly grown on highly ordered pyrolytic graphite, by means of Kelvin probe force microscopy (KPFM) and ultraviolet photoemission spectroscopy (UPS). This study underlines the importance of a controlled environment and the resulting crystallinity to achieve high WF in MoO3. UPS is proved to be suitable for determining higher WF attributed to 2D islands on a substrate with lower WF, yet only in particular cases of sufficient coverage. KPFM remains a method of choice for nanoscale investigations, especially when conducted under ultrahigh vacuum conditions. Our experimental results are supported by density functional theory calculations of electrostatic potential, which indicate that oxygen vacancies result in anisotropy of WF at the sides of the MoO3 monolayer. These novel insights into the electronic properties of 2D-MoO3 are promising for the design of electronic devices with high WF monolayer films, preserving the transparency and flexibility of the systems.

(Less)
Please use this url to cite or link to this publication:
author
; ; ; ; ; ; ; ; and , et al. (More)
; ; ; ; ; ; ; ; ; ; and (Less)
organization
publishing date
type
Contribution to journal
publication status
published
subject
keywords
2D, anode material, electrostatic potential, KPFM, molybdenum oxide, monolayer, MoO, UPS, work function
in
ACS Applied Materials and Interfaces
volume
14
issue
39
pages
10 pages
publisher
The American Chemical Society (ACS)
external identifiers
  • pmid:35976059
  • scopus:85136735093
ISSN
1944-8244
DOI
10.1021/acsami.2c09946
language
English
LU publication?
yes
id
f195eb1e-ef47-4eb3-b0ce-77d8d4a3357f
date added to LUP
2022-10-24 11:33:02
date last changed
2024-06-13 08:03:40
@article{f195eb1e-ef47-4eb3-b0ce-77d8d4a3357f,
  abstract     = {{<p>We propose that the crystallinity of two-dimensional (2D) materials is a crucial factor for achieving highly effective work function (WF) modification. A crystalline 2D MoO3 monolayer enhances substrate WF up to 6.4 eV for thicknesses as low as 0.7 nm. Such a high WF makes 2D MoO3 a great candidate for tuning properties of anode materials and for the future design of organic electronic devices, where accurate evaluation of the WF is crucial. We provide a detailed investigation of WF of 2D α-MoO3 directly grown on highly ordered pyrolytic graphite, by means of Kelvin probe force microscopy (KPFM) and ultraviolet photoemission spectroscopy (UPS). This study underlines the importance of a controlled environment and the resulting crystallinity to achieve high WF in MoO3. UPS is proved to be suitable for determining higher WF attributed to 2D islands on a substrate with lower WF, yet only in particular cases of sufficient coverage. KPFM remains a method of choice for nanoscale investigations, especially when conducted under ultrahigh vacuum conditions. Our experimental results are supported by density functional theory calculations of electrostatic potential, which indicate that oxygen vacancies result in anisotropy of WF at the sides of the MoO3 monolayer. These novel insights into the electronic properties of 2D-MoO3 are promising for the design of electronic devices with high WF monolayer films, preserving the transparency and flexibility of the systems.</p>}},
  author       = {{Kowalczyk, Dorota A. and Rogala, MacIej and Szałowski, Karol and Belić, Domagoj and Dąbrowski, Paweł and Krukowski, Paweł and Lutsyk, Iaroslav and Piskorski, Michał and Nadolska, Aleksandra and Krempiński, Patryk and Le Ster, Maxime and Kowalczyk, Paweł J.}},
  issn         = {{1944-8244}},
  keywords     = {{2D; anode material; electrostatic potential; KPFM; molybdenum oxide; monolayer; MoO; UPS; work function}},
  language     = {{eng}},
  month        = {{10}},
  number       = {{39}},
  pages        = {{44506--44515}},
  publisher    = {{The American Chemical Society (ACS)}},
  series       = {{ACS Applied Materials and Interfaces}},
  title        = {{Two-Dimensional Crystals as a Buffer Layer for High Work Function Applications : The Case of Monolayer MoO<sub>3</sub>}},
  url          = {{http://dx.doi.org/10.1021/acsami.2c09946}},
  doi          = {{10.1021/acsami.2c09946}},
  volume       = {{14}},
  year         = {{2022}},
}