Goddard Space Flight Center, Greenbelt, Maryland 20771
ENGINEERING COLLOQUIUM
Monday, October 27, 2008 / 3:30 PM, Building 3 Auditorium
Marc Baldo
"High Efficiency Organic Solar Concentrators"
ABSTRACT -- It has long been recognized that luminescent solar concentrators (LSCs) are perhaps the ideal solar concentrator for photovoltaic cells. LSCs are expected to be inexpensive to manufacture and can generate theoretically unlimited optical concentrations without the need to track the sun. But losses within LSCs have prevented their application. In this talk, we will address recent developments in photovoltaic cells and LSC technology that prompt a renewed examination of this technology. In particular, we will discuss organic solar concentrators, a class of luminescent solar concentrators that exploit advances in thin film organic semiconductor technology and low cost manufacturing processes to create efficient, large area optical concentrators for inorganic solar cells. We report single and tandem waveguide organic solar concentrators with quantum efficiencies exceeding 50% and projected power efficiencies up to 6.8%. Near field energy transfer, solid state solvation, and phosphorescence are employed within a thin film organic coating on glass to substantially reduce self absorption losses, enabling flux gains exceeding F = 10, meaning that a photovoltaic cell attached to the concentrator generates approximately 10 times the power of the photovoltaic cell without optical concentration. Flux gains of F > 10 in organic solar concentrators should enable the economical use of high performance photovoltaic cells in low cost systems. We will conclude by examining key unsolved problems and the limits of the technology.
SPEAKER -- Marc Baldo is the Esther and Harold E. Edgerton Career Development Associate Professor of Electrical Engineering and Computer Science at the Massachusetts Institute of Technology (MIT). Marc received his B.Eng. from the University of Sydney in 1995 with first class honors and university medal. He received his Ph.D. from Princeton University in 2001, where he helped develop phosphorescent organic light emitting devices‚ now the efficiency standard for organic displays and solid state lighting. He has been at MIT since 2002. At MIT he has worked on the spin dependence of exciton formation in organic light emitting devices, demonstrating that selective use of spin orbit coupling can increase fluorescent efficiencies. He has also investigated the use of photosynthetic materials and architectures in organic solar cells. His work on organic solar concentrators is an outcome of the investigations of photosynthesis.