InGaAs/GaAsSb type-II quantum dots for intermediate band solar cell

We have fabricated and characterized InGaAs/GaAsSb quantum dots solar cells (QDSCs) with a type-II band alignment structure. The photoluminescence (PL) spectrum indicates that radiative recombination in QDs is suppressed by embedding QDs with GaAsSb layers. In the excitation power dependence of PL, the PL peak of QDs embedded with GaAsSb layers show a large blueshift as reported for the case of a type-II band alignment. The external quantum efficiency (EQE) of QDSC increases in the longer wavelength range due to additive contributions from QD layers inserted in the intrinsic region. Further, an EQE increase due to photocurrent production by 2-step photon absorption measured for samples with InGaAs/GaAsSb structure indicates a higher response compared to the sample without GaAsSb layers.