Symposium EN06: Silicon for Photovoltaics

Stephanie Essig, University of Stuttgart

Challenges in the Realization of Perovskite/Si Tandem Solar Cells

Written by Henry Quansah Afful

Silicon-based solar cells have much higher efficiency when combined with other top cells having much wider bandgap, referred to as tandem solar cell design. Increasing the number of junctions (cells) increases the efficiency beyond 30 percent. However, the efficiency does not increase indefinitely as 6-junction devices were found to have comparable efficiency as the three-junction devices. This results from the extra complexity associated with the increase in number of top cells. These cells can be interconnected via different designs most notable of which is a 2-terminal tandem design. Stephanie Essig showed how the solar cell efficiency could also be increased via the 3-terminal and 4-terminal tandem designs. A 4-terminal GaInP/Si 2-junction tandem device had efficiency improved to beyond 30 percent. Essig demonstrated also that the challenges associated with the 3- and 4-terminal designs can be overcome by having an optimal voltage ratio between the top and bottom cells.