RT Conference Proceedings
SR 00
A1 Antolín Fernández, Elisa
A1 Martí Vega, Antonio
A1 García-Linares Fontes, Pablo
A1 Cánovas Díaz, Enrique
A1 Fuertes Marrón, David
A1 Luque López, Antonio
A1 Farmer, C.D.
A1 Stanley, Colin
T1 Demonstration and Analysis of the Photocurrent by absorption of two sub-bandgap photons in a quantum dot intermediate band solar cell
YR 2008
FD 01/09/2008-05/09/2008
K1 High Efficiency; Intermediate Band; Quantum Dots
AB In order to surpass the efficiency limit of single gap solar cells, intermediate band solar cells (IBSC)  have to fulfill two requirements: the production of extra photocurrent by absorption of sub-bandgap photons in  electronic transitions involving the intermediate band (IB) and the preservation of a high output voltage, not limited  by the existence of this band. This work presents experimental evidence of the production of electron-hole pairs by  absorption of two sub-bandgap photons in IBSC prototypes fabricated with InAs/GaAs QD material. The  experiments were carried out at low temperatures using a specifically designed modulated photocurrent measurement  set-up with two light beams. The results are analysed with the help of a simple equivalent circuit model. This  analysis is also used to highlight the relevance of the two-photon mechanism demonstrated in the experiment. It is  discussed that, although the absorption of sub-bandgap photons in one of the IB transitions and subsequent thermal  escape of carriers is a sufficient mechanism to obtain a photocurrent enhancement, the absorption of sub-bandgap  photons in both transitions involving the IB is a requisite for the voltage preservation in IBSCs.
T2 23rd European Photovoltaic Solar Energy Conference
ED Valencia, España
SN 3-936338-24-8
AV Published
LK http://oa.upm.es/3578/