Radiative and non-radiative processes in intermediate band solar cells

Intermediate band solar cells (IBSC) have emerged as an alternative design for third generation solar cells that could lead to dramatical improvements of the power conversion efficiencies. For this concept to work the intermediate band (IB) has to be located in the forbidden energy gap of the barrier material and to be separated by zero density of states from the valence and conduction band of the barrier material. We have demonstrated that a k · p multiband theory with periodic boundary conditions can easily be applied to predict electronic and absorption characteristics, as well as radiative and non-radiative carrier life-times between IB induced by semiconductor quantum dot (QD) arrays. We have identified that the most detrimental effect that might affect proper operation of the IBSC is caused by very fast, ~ps, Auger electron cooling non-radiative process. We discuss possible QD array designs that can suppress fast Auger electron cooling.