Colloquium

Plasmon excitation in thin film silicon solar cells

Prof. Franz-Josef Haug
School of Engineering
Ecole Polytechnique Fédérale de Lausanne
Switzerland
Wednesday, October 21, 2009
Higgins 310, 4 pm

Plasmon excitations are traditionally a subject studied in optics and certain applications in telecommunication. Some of their properties could also be interesting for light confinement in thin film solar cells, but it should be noted that plasmon excitations come in two different flavors; the first is the excitation of surface plasmon polaritons (SPPs) which are propagating waves along the interface between a metal and a dielectric. This type of interface is common in thin film solar cells, and the attenuation of SPPs in their propagation direction represents an undesired loss mechanism. It will be shown how the device design can lessen such parasitic absorption losses. A second and quite different plasmonic effect is the collective oscillation of the free charge carries in metallic nano-particles. For sufficiently small particle radius, such oscillations behave like an electric dipole driven by electromagnetic radiation. The angular radiation pattern of the dipole represents a favorable situation for light scattering as evidenced by enhanced photocurrent after incorporation into thin film silicon solar cells.