Over the last decades, solar cells have received more and more attention from scientific community as one potential candidate to replace fossil fuels, as constitute a more environmentally friendly technology. As an important drawback of the first and second generation of solar cells, about 30% of photons with energy lower than absorber band-gap are lost. In order to reduce these losses, some smart strategies have been proposed in the third generation of solar cells. Among these, the application of nanostructured materials such as quantum wells, superlattices and quantum dots has been found attractive for promoting solar cell efficiency. By using nanostructured materials, improvements to the spectral response of cells in the energy region below the absorption edge of host material are expected. That is, some photons with energies lower than bulk band-gap can be now absorbed, increasing thereby short-circuit current density of solar cell which could improve solar cell efficiency as well. In this talk, it is presented results on the use of quantum wells and superlattices to enhance GaAs and Kesterite solar cell efficiency. In particular, a theoretical work is presented where the impact of quantum well width, barrier width, well depth and well number is evaluated. Besides, conditions that favor the formation of a mini-band (intermediate-band) without and under an electric field are presented, which were studied by the Transfer Matrix Method. As an important result, it is found that solar cell efficiencies higher than 30% can be obtained by using superlattice solar cells. Conditions for optimizing solar cell performance are presented and discussed.
Key Words: Kesterite solar cells, Quantum Wells, Superlattices, Quantum confinement
