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Issue 36, 2017
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Carrier relaxation dynamics in type-II ZnO/CdSe quantum dot heterostructures

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Abstract

Semiconductor heterostructures with type-II band alignment are well known for their engineering property of efficient charge separation in photogenerated carriers. Herein, type-II CdSe/ZnO core/shell quantum dot heterostructures with CdSe shells of different thicknesses have been synthesized and a study of carrier dynamics is carried out using femtosecond transient absorption and picosecond emission spectroscopy. Carrier lifetime measurements by transient emission spectroscopy have revealed reduced electron–hole overlap in the type-II localization regime of ZnO/CdSe heterostructures. Femtosecond transient absorption studies have revealed hot electron transfer from CdSe shell to ZnO core prior to electron cooling in the CdSe shell. In addition, a surface channel for the hole cooling process has been identified in the transient absorption measurements. Effects of carrier trapping at interfacial defect states and type-II localization on carrier recombination have been recognized in our transient absorption and emission studies of ZnO/CdSe QDs heterostructure.

Graphical abstract: Carrier relaxation dynamics in type-II ZnO/CdSe quantum dot heterostructures

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Publication details

The article was received on 16 Jun 2017, accepted on 18 Aug 2017 and first published on 18 Aug 2017


Article type: Paper
DOI: 10.1039/C7CP04069E
Citation: Phys. Chem. Chem. Phys., 2017,19, 24896-24902
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    Carrier relaxation dynamics in type-II ZnO/CdSe quantum dot heterostructures

    S. Verma and H. N. Ghosh, Phys. Chem. Chem. Phys., 2017, 19, 24896
    DOI: 10.1039/C7CP04069E

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