The authors describe performance enhancement in InAs/GaAs quantum dot solar cells (QDSCs) using hydrogen plasma treatment. Photoluminescence (PL) and time-resolved PL revealed clearly decreased defect levels in QDSCs and improved crystal quality after hydrogen passivation. As a result, the open-circuit voltage and efficiency of the hydrogen-treated QDSCs were largely increased about 70mV and 10%, respectively. (C) 2015 American Vacuum Society.