In order to enhance absorption at infrared range for GaAs-based solar cells, multi-stack InGaAs vertical-coupled quantum dots (VCQDs) of 5 nm GaAs spacers are grown in the active region. We investigated the photovoltaic response for the solar cells by increasing the layer numbers of VCQDs. The device with nine-layer InGaAs VCQDs shows an enhanced short-circuit current density of 10.5 mA/cm(2). The value is increased by 42% compared to the GaAs reference device. However, the open-circuit voltage is reduced from 0.88 to 0.54 V. (C) 2011 Elsevier B.V. All rights reserved.