Transition and recombination rates in intermediate band solar cells

The interband transition rate and surface recombination rate of carriers in quantum dots, as two effective parameters to optimize the photocurrent and effciency of the intermediated band solar cells, have been classically studied. Formulation of these rates shows that they depend on the recombination lifetime of the carriers. This dependency may play the role of recombination or generation centers to the quantum dots. We have calculated these rates for two different values of recombination lifetimes. We have concluded that for a longer lifetime, quantum dots act as carrier generation centers and enhance the photocurrent and efficiency of the solar cell. It is also shown that there is an optimal number of stacked QD layers to be incorporated in the i-region in order to produce the maximum photocurrent.