Voltage limitation analysis in strain-balanced InAs/GaAsN quantum dot solar cells applied to the intermediate band concept

• Published in: Solar energy materials and solar cells Vol. 132; pp. 178 - 182
• Main Authors: Linares, P.G., López, E., Ramiro, I., Datas, A., Antolín, E., Shoji, Y., Sogabe, T., Okada, Y., Martí, A., Luque, A.
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 01.01.2015
• Subjects: Band anticrossing; Barriers; Concentrated light; Current density; Dislocations; Electric potential; GaAsN; Indium arsenides; Intermediate band; Photovoltaic cells; Quantum dot; Quantum dots; Solar cell; Solar cells; Volatile organic compounds; Voltage; Solar cell; Band anticrossing; Quantum dot; Concentrated light; Intermediate band; GaAsN
• ISSN: 0927-0248; 1879-3398
• DOI: 10.1016/j.solmat.2014.08.041

Several attempts have been carried out to manufacture intermediate band solar cells (IBSC) by means of quantum dot (QD) superlattices. This novel photovoltaic concept allows the collection of a wider range of the sunlight spectrum in order to provide higher cell photocurrent while maintaining the open-circuit voltage (VOC) of the cell. In this work, we analyze InAs/GaAsN QD-IBSCs. In these cells, the dilute nitrogen in the barrier plays an important role for the strain-balance (SB) of the QD layer region that would otherwise create dislocations under the effect of the accumulated strain. The introduction of GaAsN SB layers allows increasing the light absorption in the QD region by multi-stacking more than 100 QD layers. The photo-generated current density (JL) versus VOC was measured under varied concentrated light intensity and temperature. We found that the VOC of the cell at 20K is limited by the bandgap of the GaAsN barriers, which has important consequences regarding IBSC bandgap engineering that are also discussed in this work. •InAs/GaAsN QDs are proposed as a candidate material for the IBSC concept.•The dilute nitrogen in the barrier allows strain-balancing the stacked QD layer structure.•InAs/GaAsN QD cells are designed and fabricated with a large number of QD layers in order to enhance QD absorption.•InAs/GaAsN QD cell and GaAs control cell are subject to JL–VOC concentrated light experiments at low temperature in order to verify the voltage preservation principle.•The maximum VOC of the cell is limited by the GaAsN barrier material at approximately 1.23V.