Quantum dots (QDs) have attracted much attention for use in photovoltaic applications because of their potential for overcoming the limits of conventional single-junction devices. One problem associated with solar cells using QDs is that the open-circuit voltage (V oc) always decreases with the addition of QDs with respect to the reference cell without QDs. Here, we report the investigation of current-voltage characteristics in Ge/Si QD solar cells in the temperature range from 100 to 300â K. We show that even though V oc decreases with increasing temperature, it depends on the nominal Ge thickness, indicating that V oc reduction is primarily caused by a decrease in the bandgap energy of the cell. From photoluminescence decay measurements, we found that rapid carrier extraction from QDs occurred in the solar cells; this process eliminates the quasi-Fermi energy splitting between the QDs and the host semiconductor and causes V oc reduction in QD solar cells.
CITATION STYLE
Tayagaki, T., Hoshi, Y., & Usami, N. (2013). Investigation of the open-circuit voltage in solar cells doped with quantum dots. Scientific Reports, 3. https://doi.org/10.1038/srep02703
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