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Study of quantum dots on solar energy applications

This thesis studies p-i-n GaAs solar cells with self-assembled InAs quantum dots (QDs) inserted. The values of this work lie in three aspects. First, by comparing the cell performance with QDs in the i-region and the n-region, the photocurrent (PC) production from QDs by thermal activation and/or intermediate band (IB) absorption is proved to be much lower in efficiency than tunneling. Second, the efficiency of PC production from QDs, characterized by PC spectrum, is helpful to design QD-based photodetectors. Third, closely spaced InAs QD layers allow a strong inter-layer tunneling, leading to an effective PC production from QD deep states, potential for solar cell application. Fourth, from the temperature-dependent PC spectra the minority photohole thermal escape is found to be dominant on PC production from QDs in the n-region. The thermal activation energy reflects the potential variations formed by electron filling in QDs. Apart from InAs QDs, this thesis also explores the blinking correlation between two colloidal CdSe QDs. For QD distance of 1 µm or less, there is a bunched correlation at delay τ = 0, meaning that the two QDs blink synchronously. Such correlation disappears gradually as QD distance increases. The correlation is possibly caused by the stimulated emission between the two nearby QDs. / QC 20120507

Identiferoai:union.ndltd.org:UPSALLA1/oai:DiVA.org:kth-94021
Date January 2012
CreatorsShang, Xiangjun
PublisherKTH, Teoretisk kemi och biologi, Stockholm
Source SetsDiVA Archive at Upsalla University
LanguageEnglish
Detected LanguageEnglish
TypeDoctoral thesis, comprehensive summary, info:eu-repo/semantics/doctoralThesis, text
Formatapplication/pdf
Rightsinfo:eu-repo/semantics/openAccess
RelationTrita-BIO-Report, 1654-2312 ; 2012:12

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