Journal
PROGRESS IN PHOTOVOLTAICS
Volume 25, Issue 1, Pages 76-86Publisher
WILEY-BLACKWELL
DOI: 10.1002/pip.2815
Keywords
quantum dot; columnar dots; intermediate-band solar cell; antimony; GaAsSb layer; AlGaAsSb spacer layer
Funding
- Ministry of Science and Technology, Taiwan, R.O.C. [MOST 104-2221-E-155-028, MOST 105-2221-E-155 -062]
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This study demonstrated the feasibility of fabricating a highly stacked vertically aligned InGaAs/GaAs(Sb) quantum dot (QD) structure with an AlGaAsSb spacer layer for improving the device performance of QD intermediate-band solar cell (QD-IBSC) devices. The power-dependent photoluminescence measurements of the proposed structure revealed a blueshift in the QD ground-state emissions when the excitation power was increased, indicating the formation of an intermediate band inside the QD structure. Capping the InGaAs QDs with a GaAsSb layer prevented the QDs from collapsing because there was less In-Ga intermixing between the QDs and GaAsSb layer. In addition to maintaining the QD structure, the carrier lifetime was extended by tuning the energy band alignment of the InGaAs/GaAsSb QD structure. Inserting the AlGaAsSb layer into the spacer layer increased the band gap, which in turn increased the open-circuit voltage of the QD-IBSC. The QD-IBSC in this work shows an extension of external-quantum efficiency by up to 1200nm (compared with a GaAs reference cell) through the absorption by QDs and increased the open-circuit voltage from 0.67 to 0.70V by adopting the AlGaAsSb spacer layer. These results confirm that adopting a columnar InGaAs/GaAs(Sb) QD structure with a AlGaAsSb spacer layer can enhance the performance of QD-IBSC devices. Copyright (c) 2016 John Wiley & Sons, Ltd.
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