"Silicon Solar Cell Efficiency Improvement Employing Photoluminescent Nanostructures"

Dr. Rosendo López Delgado
Posgrado en Nanotecnología
Departamento de Física
Universidad de Sonora



Silicon based solar cells have captured the largest portion of the total market of photovoltaic devices, mostly due to its relatively high efficiency. However, silicon exhibits some limitations in the energy conversion due to its absorption range of light. The underlying reason is that in principle only photons with energy greater than the bandgap can be absorbed, but even photons with energies much larger than the bandgap have a probability of interacting with vibrational modes or crystal phonons, in a process referred to as thermalization, rather than producing electron-hole pairs. These fundamental losses can be ameliorated with the utilization of luminescent materials.

To improve the utilization of energetic photons that contribute to thermalization, the alternative proposed is to employ down-shifting materials, which are able to absorb high energy photons and emit lower energy photons that fall within the range of absorption by the underlying solar cell.

In this presentation, photoluminescent nanostructures, such as, semiconductor quantum dots, rare earth doped films and organic material as chlorophyll are employed in photovoltaic technologies as photon downshifting layers on functional solar cells.

The proposed methods represent a promising and cost-effective alternative to achieve higher efficiencies in photovoltaic devices, and the obtained results demonstrate that the application of down-converting materials is a viable strategy to improve the efficiency of Silicon solar cells with mass-compatible techniques that could serve to promote their widespread utilization.