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Understanding intermediate-band solar cells

Abstract

The intermediate-band solar cell is designed to provide a large photogenerated current while maintaining a high output voltage. To make this possible, these cells incorporate an energy band that is partially filled with electrons within the forbidden bandgap of a semiconductor. Photons with insufficient energy to pump electrons from the valence band to the conduction band can use this intermediate band as a stepping stone to generate an electron–hole pair. Nanostructured materials and certain alloys have been employed in the practical implementation of intermediate-band solar cells, although challenges still remain for realizing practical devices. Here we offer our present understanding of intermediate-band solar cells, as well as a review of the different approaches pursed for their practical implementation. We also discuss how best to resolve the remaining technical issues.

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Figure 1: Theory of the IB solar cell and basic results.
Figure 2: Energy levels and wavefunctions of a QD whose shape is assumed to be a three-dimensional parallelepiped.
Figure 3: Open-circuit voltage (VOC) of a QD IB solar cell as a function of photogenerated current density (IL) at a range of temperatures.
Figure 4: Results related to the implementation of IB solar cells based on bulk approaches.

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Correspondence to Antonio Luque.

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Luque, A., Martí, A. & Stanley, C. Understanding intermediate-band solar cells. Nature Photon 6, 146–152 (2012). https://doi.org/10.1038/nphoton.2012.1

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