Fall 2012 Biomedical Seminar Series
October 5, 2012
Two excited states for one photon: exciton fission as a way to increase solar cell efficiency
Abstract: The widespread adoption of solar energy is currently hampered by the high cost and limited efficiency of photovoltaic materials. Organic semiconductors not only offer potential cost advantages relative to inorganic materials but can also exhibit novel physical phenomena. Exciton fission is a process where a photon is absorbed to create an excited state (called an exciton) in the material. This state can spontaneously split into a pair of lower energy excitons, leading to a 200% yield of excitons per absorbed photon. If these excitons can be converted into electron-hole pairs, this process can be a way to make higher efficiency solar cells. We will describe our studies on how to understand the basic physical chemistry of this process in organic electronic materials like tetracene and rubrene. Preliminary attempts to interface exciton fission materials with silicon solar cells will be also be described. Reference ÂQuantum beats in crystalline tetracene delayed fluorescence due to triplet pair coherences produced by direct singlet fission,Â J. J. Burdett and C. J. Bardeen, J. Am. Chem. Soc., 134, 8597-8607 (2012).