You are here

  • Stephanie Hart portrait
    12/20/17

    Alumna Stephanie Hart first author on singlet fission research article

Important in molecular design of new sensitizers in organic photovoltaics

Alumna Stephanie Hart (BEng and BS in Chemistry ’17), who was advised in her undergraduate research by Professor Renee Frontiera, is first author on a paper published in Chemical Science, "Femtosecond stimulated Raman evidence for charge-transfer character in pentacene singlet fission.” Co-authors are W. Ruchira Silva, Ph.D., and Professor Frontiera. The research investigates the mechanism of singlet fission, a process used in solar cells, in which one absorbed photon generates two electrons, making for more efficient photovoltaics. 

One of the key challenges for solar energy is in developing highly efficient photovoltaic devices which are low cost and non-toxic. One promising approach in increasing overall solar cell efficiency is in the use of materials which undergo a process called singlet fission, in which the absorption of one photon can lead to the generation of two electrons. However, singlet fission is typically extremely fast, and as such as the mechanism of this process is unclear and hotly debated. 

The University of Minnesota's researchers used an ultrafast Raman spectroscopic technique to follow the structural changes in pentacene molecules during the singlet fission reaction. Surprisingly, they found evidence for states which undergo significant charge transfer, proving that charge transfer intermediates are critical in enabling singlet fission in crystalline pentacene systems. This important mechanistic insight into the singlet fission process is important in the molecular design of new sensitizers in organic photovoltaics.

About Stephanie Hart

Through the University’s Undergraduate Research Opportunity Program, Stephanie began working with Professor Renee Frontiera, where she has used ultrafast Raman spectroscopy to study charge transfer in organic semiconductors.
Through the University’s Undergraduate Research Opportunity Program, Stephanie worked with Professor Renee Frontiera, where she used ultrafast Raman spectroscopy to study charge transfer in organic semiconductors.

Stephanie was an outstanding University of Minnesota undergraduate student and received prestigious honors for her hard work in the classroom and laboratory. In 2015, she received the Department of Chemistry’s Thomas DuBruil Memorial Award for Outstanding Achievement in Undergraduate Research and, in 2016, she received the Dr. Paul F. and Patricia Guehler Chemistry Scholarship. She was also one of two University of Minnesota students named a 2016 Goldwater Scholar. 

Through the University’s Undergraduate Research Opportunity Program, Stephanie worked with Professor Frontiera, using ultrafast Raman spectroscopy to study charge transfer in organic semiconductors. For two summers, Stephanie participated in research programs at other universities. In 2015, she conducted research using fluorescence resonance energy transfer, total internal reflection fluorescence, and epifluorence microscopy to track kinetics of DNA stand displacement at liquid crystal interfaces in the Chemical Engineering Department at the University of Colorado-Boulder. As an Amgen Scholar, she worked on the construction of a single molecule microscope in the Massachusetts Institute of Technology's (MIT) Department of Chemistry in 2016.

Stephanie is now a graduate student at MIT, working with Professor Gabriela Schlau-Cohen on single-molecule and ultrafast spectroscopy.