In the present work, we investigate in detail the complex morphological, structural and chemical profile of a III–V multistep quantum dot (QD) system grown by molecular beam epitaxy and employed for the realization of enlarged bandgap intermediate band solar cells (IBSCs). The peculiar multistep design, used during the QD growth for the band-gap engineering of the IBSCs and involving a gradual compositional change from quaternary (AlInGaAs) to ternary (InGaAs) and binary (InAs) compounds, affects the morphological, chemical and structural properties of the QDs and then the electro-optical behavior of the IBSC device. These properties are assessed by combining and comparing scanning transmission electron microscopy experiments, based on high angle annular dark field imaging, with strain analysis and energy dispersive X-ray spectroscopy. The analysis demonstrates defect-free QDs embedded in the …