Intermediate band photovoltaics overview

Intermediate band photovoltaics bases its theoretical superior performance over single gap solar cells on enhancing the photogenerated solar cell current thanks to the two-step absorption of photons with energy lower than the semiconductor gap without degrading the output voltage. Its presumably better utilisation of the solar spectrum has lately become a topic of research, not only because of that of the intermediate band photovoltaic concept itself and the attempts to put it into practise, but also because it has renewed interest in some approaches, such as the up- and down- converters, the impurity photovoltaic effect and the quantum well solar cells, which also aim to utilise sub-bandgap photons. This paper reviews all these concepts.