Intermediate band solar cells: Comparison with shockley-read-hall recombination

Intermediate band solar cells are characterized by the existence of a collection of energy levels in the middle of the otherwise conventional semiconductor band gap. According to the standard Shockley-Read-Hall recombination theory, the states corresponding to these energy levels behave as nonradiative recombination centers and, therefore, are detrimental to solar cell performance. Nevertheless, the theory of the intermediate band solar cells predicts an enhancement of the solar cell efficiency well above the limiting efficiency of single gap solar cells (63.2% vs. 40.7%) when these levels exist. This paper clarifies the reasons.