Hot Carrier Solar Cells

Hot carrier cell concept utilizes selective contact, in order to extract hot energetic charge carriers, before the necessary thermalization takes place. Thermalization is experienced when photo-excited carriers collides with the cell material atoms, in an inelastic manner. Electrons that are produced from monochromatic pulse collides less, generating exponentially electron population, referred to as the Boltzmann distribution. In the first process of the electron production, the photo-excited electrons are distributed close to the band-edge, because of their fermions nature (Deambi 2011). Thereafter, collisions between the electrons occur, causing them to drift apart, and since the collision is elastic, the electrons retain their hot temperature, resulting to broad electron distribution. In the next level collisions that occur in the lattice atom turn out to be dominant, causing energy loss to the carrier to lose energy, thus decreasing the hot carrier temperatures. Therefore, for the hot carrier solar cells to be effective, they ought to gather the carriers in a previous session, before they emit temperature in form of phonon emission. In the energy generation process, the absorber region is required to display slow but measured relaxation process, as well as low recombination radiative rates (Deambi 2011). The mono-energetic contacts between the hot and cool carrier regions are considered to be suitable while using the solar cells to produce energy.

           In thermo-photovoltaic approaches, the heated body generates low and narrow energy lights, from the heat, rather than using the sun illumination as an energy source. This is considered to have high energy efficiency because, the illumination source may emit constricted bandwidth light, and secondly the cell energy can be recycled to its source, raising its efficiency.