Electron spectroscopy provides a window to study matter at the atomic and molecular level.
With it we can build a complete picture of energy materials and devices, from what atoms are present and in what chemical environments, to the electronic structure that imparts specific functionality to a device.
This is a very collaborative field and researchers from a very wide range of disciplines produce materials, surfaces and interfaces that require the fundamental characterisation offered by electron spectroscopy techniques.
Each of our spectrometers has a unique capability to explore the electrons within materials under different conditions.
In the context of dye-sensitised solar cells for example, X-ray photoelectron spectroscopy (XPS) is used to understand how the dye molecules anchor to the titanium dioxide substrate and use synchrotron-based resonant photoemission (RPES) and resonant inelastic X-ray scattering (RIXS) to probe ultra-fast electron transfer between them.
Our research aims to understand materials at the most fundamental level by characterising the atoms and electrons within them."
James O’Shea, Associate Professor and Reader in Physics
These techniques also apply to solar water splitting, but here ambient pressure XPS (AP-XPS) can be used to probe materials in a high humidity environment. In the context of two-dimensional semiconductors, a spatially resolved electron spectroscopy known as nanoESCA can probe small domains of a material down to the micron scale and completely map its electronic structure.
The new EPI2SEM facility combining nanoESCA with in-situ material growth by molecular beam epitaxy (MBE) and scanning probe microscopy (SPM) is a unique instrument for studying novel 2D semiconductor materials.
Its compatibility in terms of sample holders combined with a vacuum suitcase means that it can interface with the AP-XPS system for material studies under near-ambient pressures of gases and under solar irradiation where required.
Samples can also be transported under ultra-high vacuum to synchrotron facilities (such as the Diamond Light Source) for charge transfer dynamics measurements and X-ray absorption spectroscopy for a complete multi-technique study.
When new materials are developed for electronic applications, solar cells or electrochemical processes, their electronic band structure needs to be characterised.
With nanoESCA, even small flakes of materials can be measured, accelerating our understanding and potentially leading to the discovery of new properties long before the preparation techniques advance to larger crystals.
This vital work at atomic scale, paves the way for the development of new energy materials, technologies, and innovations.
Contact James O’Shea to find out more.
Further reading
Photoemission, resonant photoemission, and X-ray absorption of a Ru(II) complex adsorbed on rutile TiO2(110) prepared by in situ electrospray deposition.
J. Chem. Phys. 129, 114701 (2008)
Resonant inelastic X-ray scattering of a Ru photosensitizer: Insights from individual ligands to the electronic structure of the complete molecule
J. Chem. Phys. 151, 074701 (2019)
In situ XPS analysis of the atomic layer deposition of aluminium oxide on titanium dioxide.
Journal of Physical Chemistry Chemical Physics (2019)
A soft X-ray probe of a titania photoelectrode sensitized with a triphenylamine dye.
J. Chem. Phys. 154, 234707 (2021)