Efficient two-step photocarrier generation in bias-controlled InAs/GaAs quantum dot superlattice intermediate-band solar cells

Abstract We studied the effects of the internal electric field on two-step photocarrier generation in InAs/GaAs quantum dot superlattice (QDSL) intermediate-band solar cells (IBSCs). The external quantum efficiency of QDSL-IBSCs was measured as a function of the internal electric field intensity, an...

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Autores principales:	T. Kada, S. Asahi, T. Kaizu, Y. Harada, R. Tamaki, Y. Okada, T. Kita
Formato:	article
Lenguaje:	EN
Publicado:	Nature Portfolio 2017
Materias:	Medicine R Science Q
Acceso en línea:	https://doaj.org/article/9d4adf05d7234c6e9926aeea02e7f587
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spelling	oai:doaj.org-article:9d4adf05d7234c6e9926aeea02e7f5872021-12-02T11:40:50ZEfficient two-step photocarrier generation in bias-controlled InAs/GaAs quantum dot superlattice intermediate-band solar cells10.1038/s41598-017-05494-82045-2322https://doaj.org/article/9d4adf05d7234c6e9926aeea02e7f5872017-07-01T00:00:00Zhttps://doi.org/10.1038/s41598-017-05494-8https://doaj.org/toc/2045-2322Abstract We studied the effects of the internal electric field on two-step photocarrier generation in InAs/GaAs quantum dot superlattice (QDSL) intermediate-band solar cells (IBSCs). The external quantum efficiency of QDSL-IBSCs was measured as a function of the internal electric field intensity, and compared with theoretical calculations accounting for interband and intersubband photoexcitations. The extra photocurrent caused by the two-step photoexcitation was maximal for a reversely biased electric field, while the current generated by the interband photoexcitation increased monotonically with increasing electric field intensity. The internal electric field in solar cells separated photogenerated electrons and holes in the superlattice (SL) miniband that played the role of an intermediate band, and the electron lifetime was extended to the microsecond scale, which improved the intersubband transition strength, therefore increasing the two-step photocurrent. There was a trade-off relation between the carrier separation enhancing the two-step photoexcitation and the electric-field-induced carrier escape from QDSLs. These results validate that long-lifetime electrons are key to maximising the two-step photocarrier generation in QDSL-IBSCs.T. KadaS. AsahiT. KaizuY. HaradaR. TamakiY. OkadaT. KitaNature PortfolioarticleMedicineRScienceQENScientific Reports, Vol 7, Iss 1, Pp 1-10 (2017)
institution	DOAJ
collection	DOAJ
language	EN
topic	Medicine R Science Q
spellingShingle	Medicine R Science Q T. Kada S. Asahi T. Kaizu Y. Harada R. Tamaki Y. Okada T. Kita Efficient two-step photocarrier generation in bias-controlled InAs/GaAs quantum dot superlattice intermediate-band solar cells
description	Abstract We studied the effects of the internal electric field on two-step photocarrier generation in InAs/GaAs quantum dot superlattice (QDSL) intermediate-band solar cells (IBSCs). The external quantum efficiency of QDSL-IBSCs was measured as a function of the internal electric field intensity, and compared with theoretical calculations accounting for interband and intersubband photoexcitations. The extra photocurrent caused by the two-step photoexcitation was maximal for a reversely biased electric field, while the current generated by the interband photoexcitation increased monotonically with increasing electric field intensity. The internal electric field in solar cells separated photogenerated electrons and holes in the superlattice (SL) miniband that played the role of an intermediate band, and the electron lifetime was extended to the microsecond scale, which improved the intersubband transition strength, therefore increasing the two-step photocurrent. There was a trade-off relation between the carrier separation enhancing the two-step photoexcitation and the electric-field-induced carrier escape from QDSLs. These results validate that long-lifetime electrons are key to maximising the two-step photocarrier generation in QDSL-IBSCs.
format	article
author	T. Kada S. Asahi T. Kaizu Y. Harada R. Tamaki Y. Okada T. Kita
author_facet	T. Kada S. Asahi T. Kaizu Y. Harada R. Tamaki Y. Okada T. Kita
author_sort	T. Kada
title	Efficient two-step photocarrier generation in bias-controlled InAs/GaAs quantum dot superlattice intermediate-band solar cells
title_short	Efficient two-step photocarrier generation in bias-controlled InAs/GaAs quantum dot superlattice intermediate-band solar cells
title_full	Efficient two-step photocarrier generation in bias-controlled InAs/GaAs quantum dot superlattice intermediate-band solar cells
title_fullStr	Efficient two-step photocarrier generation in bias-controlled InAs/GaAs quantum dot superlattice intermediate-band solar cells
title_full_unstemmed	Efficient two-step photocarrier generation in bias-controlled InAs/GaAs quantum dot superlattice intermediate-band solar cells
title_sort	efficient two-step photocarrier generation in bias-controlled inas/gaas quantum dot superlattice intermediate-band solar cells
publisher	Nature Portfolio
publishDate	2017
url	https://doaj.org/article/9d4adf05d7234c6e9926aeea02e7f587
work_keys_str_mv	AT tkada efficienttwostepphotocarriergenerationinbiascontrolledinasgaasquantumdotsuperlatticeintermediatebandsolarcells AT sasahi efficienttwostepphotocarriergenerationinbiascontrolledinasgaasquantumdotsuperlatticeintermediatebandsolarcells AT tkaizu efficienttwostepphotocarriergenerationinbiascontrolledinasgaasquantumdotsuperlatticeintermediatebandsolarcells AT yharada efficienttwostepphotocarriergenerationinbiascontrolledinasgaasquantumdotsuperlatticeintermediatebandsolarcells AT rtamaki efficienttwostepphotocarriergenerationinbiascontrolledinasgaasquantumdotsuperlatticeintermediatebandsolarcells AT yokada efficienttwostepphotocarriergenerationinbiascontrolledinasgaasquantumdotsuperlatticeintermediatebandsolarcells AT tkita efficienttwostepphotocarriergenerationinbiascontrolledinasgaasquantumdotsuperlatticeintermediatebandsolarcells
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Efficient two-step photocarrier generation in bias-controlled InAs/GaAs quantum dot superlattice intermediate-band solar cells

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