Control of exciton spin relaxation by electron-hole decoupling in type-II nanocrystal heterostructures

Jun He; Shun S. Lo; Jeongho Kim; Gregory D. Scholes

doi:10.1021/nl802668s

Control of exciton spin relaxation by electron-hole decoupling in type-II nanocrystal heterostructures

Jun He, Shun S. Lo, Jeongho Kim, Gregory D. Scholes

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42 Scopus citations

Abstract

The electron spin flip relaxation dynamics in type II CdSe/CdTe nanorod heterostructures are investigated by an ultrafast polarization transient grating technique. Photoexcited charge separation in the heterostructures suppresses the electron-hole exchange interaction and their recombination, which reduces the electron spin relaxation rate in CdSe nanocrystals by 1 order of magnitude compared to exciton relaxation. The electron orientation is preserved during charge transfer from CdTe to CdSe, and its relaxation time constant is found to be ∼5 ps at 293 K in the CdSe part of these nanorods. This finding suggests that hole spin relaxation determines the exciton fine structure relaxation rate and therefore control of exciton spin relaxation in semiconductor nanostructures is possible by delocalizing or translating the hole density relative to the electron.

Original language	English (US)
Pages (from-to)	4007-4013
Number of pages	7
Journal	Nano Letters
Volume	8
Issue number	11
DOIs	https://doi.org/10.1021/nl802668s
State	Published - Nov 2008
Externally published	Yes

All Science Journal Classification (ASJC) codes

General Chemistry
Condensed Matter Physics
Mechanical Engineering
Bioengineering
General Materials Science

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10.1021/nl802668s

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title = "Control of exciton spin relaxation by electron-hole decoupling in type-II nanocrystal heterostructures",

abstract = "The electron spin flip relaxation dynamics in type II CdSe/CdTe nanorod heterostructures are investigated by an ultrafast polarization transient grating technique. Photoexcited charge separation in the heterostructures suppresses the electron-hole exchange interaction and their recombination, which reduces the electron spin relaxation rate in CdSe nanocrystals by 1 order of magnitude compared to exciton relaxation. The electron orientation is preserved during charge transfer from CdTe to CdSe, and its relaxation time constant is found to be ∼5 ps at 293 K in the CdSe part of these nanorods. This finding suggests that hole spin relaxation determines the exciton fine structure relaxation rate and therefore control of exciton spin relaxation in semiconductor nanostructures is possible by delocalizing or translating the hole density relative to the electron.",

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year = "2008",

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language = "English (US)",

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issn = "1530-6984",

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T1 - Control of exciton spin relaxation by electron-hole decoupling in type-II nanocrystal heterostructures

AU - He, Jun

AU - Lo, Shun S.

AU - Kim, Jeongho

AU - Scholes, Gregory D.

PY - 2008/11

Y1 - 2008/11

N2 - The electron spin flip relaxation dynamics in type II CdSe/CdTe nanorod heterostructures are investigated by an ultrafast polarization transient grating technique. Photoexcited charge separation in the heterostructures suppresses the electron-hole exchange interaction and their recombination, which reduces the electron spin relaxation rate in CdSe nanocrystals by 1 order of magnitude compared to exciton relaxation. The electron orientation is preserved during charge transfer from CdTe to CdSe, and its relaxation time constant is found to be ∼5 ps at 293 K in the CdSe part of these nanorods. This finding suggests that hole spin relaxation determines the exciton fine structure relaxation rate and therefore control of exciton spin relaxation in semiconductor nanostructures is possible by delocalizing or translating the hole density relative to the electron.

AB - The electron spin flip relaxation dynamics in type II CdSe/CdTe nanorod heterostructures are investigated by an ultrafast polarization transient grating technique. Photoexcited charge separation in the heterostructures suppresses the electron-hole exchange interaction and their recombination, which reduces the electron spin relaxation rate in CdSe nanocrystals by 1 order of magnitude compared to exciton relaxation. The electron orientation is preserved during charge transfer from CdTe to CdSe, and its relaxation time constant is found to be ∼5 ps at 293 K in the CdSe part of these nanorods. This finding suggests that hole spin relaxation determines the exciton fine structure relaxation rate and therefore control of exciton spin relaxation in semiconductor nanostructures is possible by delocalizing or translating the hole density relative to the electron.

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JO - Nano Letters

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Control of exciton spin relaxation by electron-hole decoupling in type-II nanocrystal heterostructures

Abstract

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