Universidad Politécnica de Madrid

Instituto de energía solar

R&D at IES

Intermediate band materials and solar cells

This activity focuses on the development of the intermediate band solar cell (IBSC), a novel solar cell concept proposed by the group in 1997 [A. Luque and A. Martí, Physical Review Letters 78 (26), 5014 (1997)  https://doi.org/10.1103/PhysRevLett.78.5014].

When implemented in a semiconductor host, the core of the idea consists in harvesting below bandgap energy photons thanks to the so-called “intermediate band (IB)”. This IB, located inside the semiconductor bandgap, acts as a step stone, allowing the absorption of the sub-bandgap photons labelled “1” and “2” in the figure. The electron-hole pairs generated through this two-photon absorption process add to those conventionally generated by the absorption of photons with energy above the bandgap (photon “3” in the figure).

Around this idea, other research lines, such as:

• quantum mechanical calculations,
• nanostructures,
• molecular beam epitaxy, and 
• advanced characterization tools and device processing,

have nucleated in order to make the development of this cell possible. 

These lines will be described in the next sections.


Contact person: Prof. Antonio Martí

Selected publications

  1. A. Luque and A. Martí, "Increasing the efficiency of ideal solar cells by photon induced transitions at intermediate levels", Physical Review Letters, vol. 78, pp. 5014–5017, 1997.

  2. I. Ramiro, A. Martí, E. Antolín, and A. Luque, "Review of experimental results related to the operation of intermediate band solar cells", IEEE Journal of Photovoltaics, vol. 4, pp. 736-748, 2014. (DOI: 10.1109/jphotov.2014.2299402)

  3. A. Luque, A. Martí, E. Antolín, and C.Tablero, "Intermediate bands versus levels in non-radiative recombination", Physica B, vol. 382, pp. 320-327, 2006. (DOI: 10.1016/j.physb.2006.03.006)

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