Thursday, August 12, 2010
Excitrons and Photovoltaics.
Hot excitons are created by the absorption of energetic blue or near-ultraviolet photons. Hot excitons quickly lose their excess kinetic energy through electron-phonon interactions and convert it into heat, which accounts for significant loss of conversion efficiency in photovoltaics. To increase efficiency, one needs to make use of this excess heat preferably by direct conversion to electricity (simlar to what is done in spaceceaft) and/or by going to a lower energy regime, i.e., using the visible portion of the spectrum and lower to generate cooler, multiple excitrons via quantum dots. These excitrons decay within 20-100 picoseconds making harvesting difficult. Ettori says photons are doves. Electrons are motorcycles (since they are 2-dimensional). Protons are trucks and therefore neutrons must be too although they had not yet been discovered. So we want to convert doves to motocycles without the trucks stealing the energy. Right, Ettori? Maybe not, doves also convert to Majorana fermions, don't they, Ettori? Should I have said happy 104th on August 5 or are you really gone?