Device simulation of intermediate band solar cells: Dependence on number of intermediate band layers

Intermediate band solar cell (IBSC) is a concept to achieve a higher conversion efficiency than the Shockley-Queisser limit of a single junction cell. Current-voltage characteristics of multi-stacked quantum dot solar cells for the application for IBSCs show a clear dependence on the quantum dot stacking layer numbers. Increasing the number of stacking layers, short-circuit current density is increased but open-circuit voltage is reduced compared with a control cell. We studied the dependence of IB layer numbers on IBSC performance by using self-consistent drift-diffusion method for IBSCs with localized IB in IB region. Our results show the similar dependence of current-voltage characteristics for experimental results under 1 sun illumination. Under 1000 suns, the degradation of open-circuit voltage is reduced and the net carrier generation rate is well controlled by incident photon flux densities. As a result, to evaluate the potential of multi-stacked quantum dot solar cells for IBSC operations, assessments of the inclement of short-circuit current densities under low concentration and the change of open-circuit voltages under high concentration are important.