Drift-diffusion simulations of InAs/AlAsSb quantum dot intermediate-band solar cells

We present drift-diffusion simulations of InAs QDs embedded in AlAsSb, which is a promising candidate system for realizing intermediate band solar cells as it features bandgaps close to the ideal, a nearly flat type-II valence band lineup. Absorption coefficients calculated by the 8-band k.p method have been used, along with. It is concluded that state-of-art InAs/AlAsSb QDs can only provide modest efficiency increases far below what Detailed-Balance theory predicts, and that the major reason for the discrepancy comes from the idealized modeling of wavelength-independent absorption often used, which fail to capture imbalances in the absorption coefficient. A few possibilities for improving the performance are presented.