Middlebury College Assistant Professor Ben Cotts on his DOE EPSCoR Award

The US Department of Energy (DOE) recently made $21 million of funding available to 29 new projects through DOE EPSCoR Lab Partnerships. Last week we spoke with Jihong Ma on her award, and this week we discuss the significance of the funding with Ben Cotts, PhD, Assistant Professor of Chemistry/Biochemistry at Middlebury College.

Please describe your lab and the type of research you do.

We are an experimental physical chemistry laboratory that uses time-resolved spectroscopy to study new forms of semiconducting materials for use in optoelectronic devices such as solar cells, LEDs, or lasers. Such materials interconvert light and electrical energy in a fraction of a second requiring time-resolved techniques to understand how they behave in these excited states. Time-resolved techniques can track excited state electrons and structural motions with short bursts of light to work to understand why different sample preparations yield lower or higher device efficiency.

The lab is in its second year and currently consists of the PI, Ben Cotts, and three undergraduate students (Eliza Wieman, Mia Tarantola, and Charlotte Zehnder).


Middlebury undergraduates Mia Tarantola '23 and Eliza Wieman '23 at the Advanced Photon Source in August 2022

What do you hope to accomplish with your project?

This project focuses on colloidal semiconductor nanocrystals (NCs), which are very small crystals of semiconducting material with appealing optoelectronic properties that can be tuned by their size, shape, composition, and surface chemistry. Some NCs can reach high optoelectronic efficiencies under certain conditions, but less is understood about maintaining their performance under high excitation conditions needed for lasers and electrically pumped LEDs. In collaboration with beamline scientist Burak Guzelturk at Argonne National Lab's Advanced Photon Source we plan to use time-resolved X-ray diffraction to understand the structural origins of efficiency losses in these materials in their excited states. Time-resolved X-ray diffraction directly probes atomic rearrangements within these NCs in their excited states and how that impacts their device performance. A team of student researchers and a postdoctoral scholar will work together to prepare and characterize NC thin films for study at Argonne's APS. Simultaneously we will work with Prof. Jihong Ma's group at University of Vermont to simulate the atomistic motions of these NCs after photoexcitation to unravel the origins of nonradiative loss pathways detrimental to device performance.


Argonne National Laboratory Beamline Scientist Burak Guzelturk, Mia Tarantola '23, and Eliza Wieman '23 during a meeting to discuss experimental plans at Argonne's Advanced Photon Source in August 2022

How does this project build on your research goals and career interests?

I previously have conducted time-resolved structural studies of NCs during my postdoctoral research at DOE labs (SLAC and Argonne). I am excited to continue work with Dr. Burak Guzelturk and to train my students to use the awesome resources of national user facilities like Argonne's Advanced Photon Source. The resources at Argonne National Lab will complement and enhance the work that we do on NCs in our lab at Middlebury to allow us to draw stronger conclusions. Additionally, I am very excited to start collaborating with experts like Prof. Jihong Ma at UVM in order to build productive scientific relationships within the State of Vermont. Such experiences will strengthen my research program and better prepare my students for their next career steps.


Ben Cotts, Mia Tarantola '23, and Eliza Wieman '23 during a meeting to discuss experimental plans at Argonne's Advanced Photon Source in August 2022

How does the DOE award help you achieve your goals?

This DOE award will help me to expand my laboratory to buy additional equipment and to work with a postdoc to help train my students and expand our capabilities. It will also help build a new collaboration with Prof. Jihong Ma at UVM to provide powerful theoretical insight to help understand and guide future experimental work. It will also help me to bring more students with me to DOE labs for experiments and to travel to conferences.