Experimental demonstration of the effect of field damping layers in quantum-dot intermediate band solar cells

Intermediate band solar cells must demonstrate the principle of voltage preservation in order to achieve high conversion efficiencies. Tunnel escape of carriers has proved deleterious for this purpose in quantum dot intermediate band solar cells. In previous works, thick spacers between quantum dot...

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Bibliographic Details
Published in:Solar energy materials and solar cells 2015-09, Vol.140, p.299-305
Main Authors: Ramiro, I., Antolín, E., Martí, A., Farmer, C.D., Stanley, C.R., Luque, A.
Format: Article
Language:English
Subjects:
Carriers
Electric fields
Electric potential
Intermediate band solar cell
Photovoltaic cells
Preservation
Quantum dots
Qunatum dots
Solar cell characterization
Solar cells
Tunnel escape
Tunnels (transportation)
Voltage
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Summary:Intermediate band solar cells must demonstrate the principle of voltage preservation in order to achieve high conversion efficiencies. Tunnel escape of carriers has proved deleterious for this purpose in quantum dot intermediate band solar cells. In previous works, thick spacers between quantum dot layers were demonstrated as a means of reducing tunnel escape, but this approach is unrealistic if a large number of quantum dot layers have to be grown. In this work we report experimental proof that the use of field damping layers is equally effective at reducing tunnel carrier escape, by reducing the potential drop in the QD-stack and the associated electric field. Moreover, we demonstrate that the fact that tunnel carrier escape takes place under short-circuit conditions does not imply that voltage preservation cannot be achieved. We describe a theory that relates the evolution of the tunnel escape to bias voltage and the preservation of the voltage in an IBSC. Temperature and voltage-dependent quantum efficiency measurements, temperature dependent open-circuit voltage measurements and calculations of the internal electric field in IBSCs serve as the basis of the proposed theory. •We have investigated experimentally the effect of Field Damping Layers in QD-IBSCs.•Field Damping Layers allow VOC preservation (at low T) in QD-IBSCs with thin spacers.•A theory relating tunnel carrier escape and VOC preservation is proposed and verified.•QE vs V measurements are shown to be a useful technique for IBSC characterization.
ISSN:0927-0248
1879-3398
DOI:10.1016/j.solmat.2015.04.029