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Descripción
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| InAs/GaAs quantum dot (QD) solar cells have been the subject of intense research during last years, not only as a strategy to overcome the Shockley-Queisser efficiency limit through novel concepts such as intermediate band solar cells, but also as a way to extend the effective bandgap of single or multi-junction (sub)cells to the near infrared. Nevertheless, QD solar cells have up to now hardly outperformed control devices. This is due to several problems, in which the wetting layer (WL) may have a relevant but relatively unexplored role. In this work we investigate the performance of InAs/GaAs QD solar cells with engineered WLs grown by molecular beam epitaxy. First we demonstrate a negative impact of the WL on the carrier extraction efficiency of standard InAs/GaAs QD solar cells. Then we analyze different strategies designed to neutralize the effect of the WL based on either a physical modification of the WL or a modification of its electronic structure. The WL thickness can be reduced by modifying the growth conditions of the GaAs capping layer: high capping rates reduce In-Ga intermixing in the QDs and, therefore, In redistribution from the QDs to the WL. Carrier transport through the WLs can also be improved by electronic coupling of the different QD/WL layers and the creation of mini-bands. Finally, the band structure of the WL can be modified and converted to type-II by adding Sb to the capping layer. We show that some of these strategies result in improvements of conversion efficiency under AM1.5 conditions of up to 125% over standard InAs/GaAs QD solar cells. | |
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Internacional
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Si |
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Nombre congreso
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SPIE OPTO 2019 (Nano and Quantum Engineered Photovoltaic Devices) |
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Tipo de participación
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960 |
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Lugar del congreso
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San Francisco, Estados Unidos |
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Revisores
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Si |
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ISBN o ISSN
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0000000000000 |
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DOI
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Fecha inicio congreso
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02/02/2019 |
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Fecha fin congreso
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09/02/2019 |
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Desde la página
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1 |
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Hasta la página
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3 |
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Título de las actas
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proceedings |