University of Toronto materials science and engineering
(MSE) researchers have demonstrated, for the first time, the key mechanism
behind how energy levels align in a critical group of advanced materials. This
discovery is a significant breakthrough in the development of sustainable
technologies such as dye-sensitized solar cells and organic light-emitting
Transition metal oxides, which are best-known for their
application as superconductors, have made possible many sustainable
technologies developed over the last two decades, including organic
photovoltaics and organic light-emitting diodes. While it is known that these
materials make excellent electrical contacts in organic-based devices, it
wasn’t known why.
In research published in Nature
Materials, MSE PhD candidate Mark T. Greiner and Professor Zheng-Hong Lu, Canada Research
Chair (Tier I) in Organic Optoelectronics, lay out the blueprint that
conclusively establishes the principle of energy alignment at the interface
between transition metal oxides and organic molecules.
“The energy-level of molecules on materials surfaces is like a
massive jigsaw puzzle that has challenged the scientific community for a very
long time,” says Lu. “There have been a number of suggested theories with many
critical links missing. We have been fortunate to successfully build these
links to finally solve this decades-old puzzle.”
With this piece of the puzzle solved, this discovery could
enable scientists and engineers to design simpler and more efficient organic
solar cells and OLEDs to further enhance sustainable technologies and help
secure our energy future.
The paper, entitled “Universal Energy-Level Alignment of
Molecules on Metal Oxides,” is available online.