Correlation between quantum dot morphology and photovoltaic performance

The use of nanostructures, such as quantum dots (QD) or quantum wells within photovoltaic (PV) devices has demonstrated enhanced current generation, but often at the expense of open-circuit voltage. QD morphology and optical quality have a direct impact on PV performance and optimizing the epitaxial growth of QDs is critical to achieve the desired benefits of QD-enhanced PV. The spatial uniformity of QD epitaxy can determine the PV performance across a large area wafer. In this paper, we demonstrate a correlation between the spatial uniformity of QD size distribution and photovoltaic conversion efficiency. A spatially varying Voc measured on QD-enhanced GaAs solar cells correlates with the presence of coalesced QDs. The results suggest the presence of large, coalesced QDs is a significant cause for a reduced Voc in QD-enhanced GaAs p-i-n solar cells.