Observatorio de I+D+i UPM

Memorias de investigación
Communications at congresses:
Two-photon photocurrent and voltage up-conversion in a quantum dot intermediate band solar cell
Research Areas
  • Photon light receptor devices,
  • Solar cells,
  • Technology of devices for engineering
It has been proposed that the use of self-assembled quantum dot (QD) arrays can break the Shockley-Queisser efficiency limit by extending the absorption of solar cells into the low-energy photon range while preserving their output voltage. This would be possible if the infrared photons are absorbed in the two sub-bandgap QD transitions simultaneously and the energy of two photons is added up to produce one single electron-hole pair, as described by the intermediate band model. Here, we present an InAs/Al 0.25Ga 0.75As QD solar cell that exhibits such electrical up-conversion of low-energy photons. When the device is monochromatically illuminated with 1.32 eV photons, open-circuit voltages as high as 1.58 V are measured (for a total gap of 1.8 eV). Moreover, the photocurrent produced by illumination with photons exciting the valence band to intermediate band (VB-IB) and the intermediate band to conduction band (IB-CB) transitions can be both spectrally resolved. The first corresponds to the QD inter-band transition and is observable for photons of energy > 1 eV, and the later corresponds to the QD intra-band transition and peaks around 0.5 eV. The voltage up-conversion process reported here for the first time is the key to the use of the low-energy end of the solar spectrum to increase the conversion efficiency, and not only the photocurrent, of single-junction photovoltaic devices. In spite of the low absorption threshold measured in our devices - 0.25 eV - we report open-circuit voltages at room temperature as high as 1.12 V under concentrated broadband illumination.
40th IEEE Photovoltaic Specialists Conference
Denver, CO, USA
Start Date
End Date
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Proc. 40th IEEE PVSC
  • Autor: Iñigo Ramiro Gonzalez (UPM)
  • Autor: Elisa Antolin Fernandez (UPM)
  • Autor: P. García-Linares
  • Autor: Esther Lopez Estrada (UPM)
  • Autor: Irene Artacho Huertas (UPM)
  • Autor: Alejandro Datas Medina (UPM)
  • Autor: Antonio Marti Vega (UPM)
  • Autor: Antonio Luque Lopez (UPM)
  • Autor: M.J. Steer
  • Autor: C.R. Stanley
Research Group, Departaments and Institutes related
  • Creador: Grupo de Investigación: Silicio y Nuevos Conceptos para Células Solares
  • Departamento: Electrónica Física
  • Centro o Instituto I+D+i: Instituto de Energía Solar
S2i 2020 Observatorio de investigación @ UPM con la colaboración del Consejo Social UPM
Cofinanciación del MINECO en el marco del Programa INNCIDE 2011 (OTR-2011-0236)
Cofinanciación del MINECO en el marco del Programa INNPACTO (IPT-020000-2010-22)