Malika Jeffries-EL and her Iowa State Univ. research group are studying polymers that can conduct electricity. Photo: Bob Elbert |
Iowa State Univ.’s Malika Jeffries-EL says she’s studying doing
structure-property studies so she can teach old polymers new tricks.
Those tricks improve the properties of certain organic polymers that mimic
the properties of traditional inorganic semiconductors and could make the
polymers very useful in organic solar cells, light-emitting diodes, and
thin-film transistors.
Conductive polymers date back to the late 1970s when researchers Alan
Heeger, Alan MacDiarmid, and Hideki Shirakawa discovered that plastics, with
certain arrangements of atoms, can conduct electricity. The three were awarded
the 2000 Nobel Prize in Chemistry for the discovery.
Jeffries-EL, an Iowa
State assistant professor
of chemistry, is working with a post-doctoral researcher and nine doctoral
students to move the field forward by studying the relationship between polymer
structures and the electronic, physical, and optical properties of the
materials. They’re also looking for ways to synthesize the polymers without the
use of harsh acids and temperatures by making them soluble in organic solvents.
The building blocks of their work are a variety of benzobisazoles,
molecules well suited for electrical applications because they efficiently
transport electrons, are stable at high temperatures and can absorb photons.
And if the polymers are lacking in any of those properties, Jeffries-EL and
her research group can do some chemical restructuring.
“With these polymers, if you don’t have the properties you need, you
can go back and change the wheel,” Jeffries-EL said. “You can change
the chemical synthesis and produce what’s missing.”
That, she said, doesn’t work with silicon and other inorganic materials for
semiconductors: “Silicon is silicon. Elements are constant.”
Polymers that can conduct electricity. Photo: Bob Elbert |
The National Science Foundation is supporting Jeffries-EL’s polymer
research with a five-year, $486,250 Faculty Early Career Development grant. She
also has support from the Iowa Power Fund (a state program that supports energy
innovation and independence) to apply organic semiconductor technology to solar
cells
The research group is seeing some results, including peer-reviewed papers
over the past two years in Physical
Chemistry Chemical Physics, Macromolecules,
the Journal of Polymer Science Part A:
Polymer Chemistry, and the Journal of
Organic Chemistry.
“This research is really about fundamental science,” Jeffries-EL
said. “We’re studying the relationships between structure and material
properties. Once we have a polymer with a certain set of properties, what can
we do?”
She and her research group are turning to the molecules for answers.
“In order to realize the
full potential of these materials, they must be engineered at the molecular
level, allowing for optimization of materials properties, leading to enhanced
performance in a variety of applications,” Jeffries-EL wrote in a research
summary. “As an organic chemist, my approach to materials begins with
small molecules.”
