Students research solar cells with HPC

The figure shows the geometry (upper left), the electron density map (upper right), the locations of electron density of the highest occupied molecular orbital (HOMO) and the lowest unoccupied molecular orbital (LUMO) of a compound that could work as a solar cell. Image courtesy of Aimée Tomlinson.

Solar energy has the potential to be the perfect renewable energy source. Unfortunately, modern solar cells are too inefficient and too expensive to achieve the technology's potential.

Researchers are hard at work to change that, however, by searching for alternative materials that could change the solar energy landscape. And they're doing it with high-performance computing.

"Organic materials provide several benefits over their inorganic analogs," explained Aimée Tomlinson, a chemistry researcher at North Georgia College & State University. Tomlinson and her colleague, Malika Jeffries-EL at Iowa State University, are working with several undergraduate chemistry students to study organic materials that could function as solar cells.

According to Tomlinson, producing organic materials for solar cells is less detrimental for the environment. These materials also have plastic-like properties, such that they can be molded into a variety of shapes. That plasticity also means they are less breakable.

"On the flip side, they are less efficient than the inorganic variety which is why a great many scientists all over the world are working on identifying materials which will give rise a more efficient organic solar cell," Tomlinson said.

The undergraduate students are able to participate as part of North Georgia’s Center for Undergraduate Research and Creative Activities new program, FUSE (Faculty-Undergraduate Summer Engagement).

Tomlinson and her students were granted 200,000 compute hours via XSEDE to study possible chemical structures for use in organic, hydrocarbon-based solar cells; most of those hours were carried out on the Ember cluster at the US National Center for Supercomputing Applications.

Quantum mechanical computations that could take as long as a week to solve on a typical computer can be solved in as little as an hour via XSEDE, said Tomlinson. Thanks to their access to advanced computing, they were able to identify a few compounds that show particular promise for use in solar cells.

The project has also served as an avenue for education.

"I taught my students how to generate the structures, upload the needed files to the supercomputer and run those jobs themselves," Tomlinson said. Although Tomlinson did the majority of the data analysis, she also taught the students how to obtain the main parameters that arise from the computations, among other skills essential to computational chemistry and material science.

Since gaining access to supercomputers in fall 2010, several students working on the project have presented research at conferences. They have also written three papers, including one that has been accepted for publication. Students will continue to present their findings in additional papers to be submitted for publication titled "An Evaluation of Hybrid Density Functional Methods when Applied to Benzobisazoles" and "Improving the Optical and Electronic Properties of Benzobisoxazoles via Aryl Substitution."

Portions of this article were based on a North Georgia News article.