Garry Rumbles, National Renewable Energy Laboratory
Excitonic Solar Cells: from Quantum Dots and Proteins to Carbon Nanotubes
Physics Division Colloquium - 3 Mar 2006

There is a critical need for an energy solution that does not produce carbon dioxide as a bi-product. While there are a few possible solutions, the direct use of solar energy to produce electricity or fuels is the only one that has the potential to provide the bulk of the worlds' energy needs for many generations. Photovoltaic solar cells offer the possibility of making a significant contribution to this effort and it is this subject that motivates the work that will be discussed in the presentation.

More specifically, the role that Excitonic Solar Cells (XSC) can play will be discussed. These are perhaps more commonly known as organic (or molecular) solar cells and with either name they represent a new class of solar cell that works with a fundamentally different physics than conventional solar cells. This difference provides a number of elegant possibilities to the creation of third-generation solar cells, where device efficiencies can exceed the ~30% thermodynamic limit of single-junction devices. This presentation will focus on colloidal quantum dots, single-wall carbon nanotubes, conjugated polymers and dendrimers as candidates for incorporation into XSCs and how their unique properties might help exceed this thermodynamic limit. The importance of understanding the fundamental photoconversion processes, the techniques that are used to follow these processes and how molecular chemistry has the potential to make a significant contribution will all be examined in detail.

ANL Physics Division Colloquium Schedule