Optical and structural properties of submonolayer InGaAs/GaAs quantum dot solar cells (SML-QDSCs) are investigated and compared with quantum well solar cells (QWSCs). Compared with InGaAs/GaAs QWSCs with a similar structure, the material quality for SML QDSCs is significantly improved with a reduced density of both crosshatch patterns and defects. This coincides with a much higher photoluminescence intensity obtained for SML QDSCs. SML QDSCs thus exhibit an increase in open circuit voltage of 70 meV and an improvement in short circuit current from 15.9 mA/cm(2) to 17.7 mA/cm(2) in comparison with QWSCs. These findings present a promising alternative to quantum wells in photovoltaic applications. (C) 2014 The Authors. Published by Elsevier B.V.