Discipline: Chemistry and Chemical Sciences
Subcategory: Materials Science
Derek C. Perry - University of Washington/Brooklyn College
Co-Author(s): Sarah Holliday, University of Washington, Seattle, Washington
In the ever-changing world of energy demand, new strides have been made to shift to renewable forms of energy over the conventional non-renewable and fossil fuels. One of these shifts includes the greater use of photovoltaic cells, which predominantly come in two forms, inorganic and organic photovoltaics (OPV), with organics being the more promising choice in the future due to the greater abundance and lower cost of their materials. OPV devices work using a semiconducting polymer as an electron donor with a fullerene (carbon structures that are a spheroidal molecule consisting of a hollow cage of atoms) as the acceptor and the light-absorbing component of the device. However, many of these polymers are dynamic and reactive, especially to oxygen and water and have been known to undergo chemical and morphological changes when illuminated under solar conditions as well as undergoing interfacial degradation as the cell is used. It is because of this reactivity that the bulk heterojunction (the region of the cell where the blend of polymer/fullerene resides) is not necessarily stable enough to result in a useful lifetime for a device. The two polymers of interest in this work are PTB7 and PTB7-th, which posses the same polymer backbone, but have different functional groups attached to them. The research presented includes monitoring the degradation of both polymers under solar conditions to determine which of the two will be more suitable to be used in OPV devices. UV-vis, infrared, and nuclear magnetic resonance spectroscopy will be used to keep track of chemical changes in the polymer during light exposure. Future work includes determining what specific features of the functional groups lend to the difference in reactivity to sunlight and air.
Funder Acknowledgement(s): National Science Foundation
Faculty Advisor: Christine Luscombe, firstname.lastname@example.org
Role: Research includes: Preparation of photovoltaic cells, solar tests (JV curves collection, external quantum efficiency tests, nuclear magnetic resonance spectroscopy, ultraviolet visible spectroscopy, and infrared spectroscopy), as well as modification of research methods and equipment.