The hybrid structure of GaAs/GaAsSb quantum well (QW)/InAs quantum dots solar cells (QDSCs) is analyzed using power-dependent and temperature-dependent photoluminescence. We demonstrate that placing the GaAsSb QW beneath the QDs forms type-II characteristics that initiate at 12% Sb composition. Current density-voltage measurements demonstrate a decrease in power efficiency with increasing Sb composition. This could be attributed to increased valence band potential in the GaAsSb QW that subsequently limits hole transportation in the QD region. To reduce the confinement energy barrier, a 2 nm GaAs wall is inserted between GaAsSb QW and InAs QDs, leading to a 23% improvement in power efficiency for QDSCs.