Excitation Energy Dependent Efficiency of Charge Carrier Relaxation and Photoluminescence in Colloidal InP Quantum Dots

Randy J. Ellingson; Jeff L. Blackburn; Pingrong Yu; Garry Rumbles; Olga I. Mićić; Arthur J. Nozik

doi:10.1021/jp025666p

Excitation Energy Dependent Efficiency of Charge Carrier Relaxation and Photoluminescence in Colloidal InP Quantum Dots

Randy J. Ellingson, Jeff L. Blackburn, Pingrong Yu, Garry Rumbles, Olga I. Mićić, Arthur J. Nozik

National Renewable Energy Laboratory

Research output: Contribution to journal › Article › peer-review

78 Scopus Citations

Abstract

Femtosecond transient absorption spectroscopy has been used together with time-integrated photoluminescence (PL) measurements to study charge carrier relaxation in colloidal InP quantum dots (QDs). Measurements of band-edge photoinduced bleaching as well as PL intensity measurements indicate that the fraction of charge carriers relaxing to the band-edge states depends on excitation wavelength, with a markedly reduced relaxation efficiency observed for excitation well above the absorption edge. The results concur with previous research on CdSe and InP QDs, and suggest that with increasing excitation energy there arise relaxation pathways involving surface or external energy states exhibiting reduced radiative efficiency. Such highly excited carriers are either inhibited or deviated from reaching the band-edge states. Excitation intensity dependent measurements indicate that those charge carriers which contribute to the band-edge absorption bleaching also contribute proportionally to the time-integrated PL spectrum.

Original language	American English
Pages (from-to)	7758-7765
Number of pages	8
Journal	Journal of Physical Chemistry B
Volume	106
Issue number	32
DOIs	https://doi.org/10.1021/jp025666p https://doi.org/10.1021/jp025666p
State	Published - 2002

NREL Publication Number

NREL/JA-590-33313

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title = "Excitation Energy Dependent Efficiency of Charge Carrier Relaxation and Photoluminescence in Colloidal InP Quantum Dots",

abstract = "Femtosecond transient absorption spectroscopy has been used together with time-integrated photoluminescence (PL) measurements to study charge carrier relaxation in colloidal InP quantum dots (QDs). Measurements of band-edge photoinduced bleaching as well as PL intensity measurements indicate that the fraction of charge carriers relaxing to the band-edge states depends on excitation wavelength, with a markedly reduced relaxation efficiency observed for excitation well above the absorption edge. The results concur with previous research on CdSe and InP QDs, and suggest that with increasing excitation energy there arise relaxation pathways involving surface or external energy states exhibiting reduced radiative efficiency. Such highly excited carriers are either inhibited or deviated from reaching the band-edge states. Excitation intensity dependent measurements indicate that those charge carriers which contribute to the band-edge absorption bleaching also contribute proportionally to the time-integrated PL spectrum.",

author = "Ellingson, {Randy J.} and Blackburn, {Jeff L.} and Pingrong Yu and Garry Rumbles and Mi{\'c}i{\'c}, {Olga I.} and Nozik, {Arthur J.}",

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T1 - Excitation Energy Dependent Efficiency of Charge Carrier Relaxation and Photoluminescence in Colloidal InP Quantum Dots

AU - Ellingson, Randy J.

AU - Blackburn, Jeff L.

AU - Yu, Pingrong

AU - Rumbles, Garry

AU - Mićić, Olga I.

AU - Nozik, Arthur J.

PY - 2002

Y1 - 2002

N2 - Femtosecond transient absorption spectroscopy has been used together with time-integrated photoluminescence (PL) measurements to study charge carrier relaxation in colloidal InP quantum dots (QDs). Measurements of band-edge photoinduced bleaching as well as PL intensity measurements indicate that the fraction of charge carriers relaxing to the band-edge states depends on excitation wavelength, with a markedly reduced relaxation efficiency observed for excitation well above the absorption edge. The results concur with previous research on CdSe and InP QDs, and suggest that with increasing excitation energy there arise relaxation pathways involving surface or external energy states exhibiting reduced radiative efficiency. Such highly excited carriers are either inhibited or deviated from reaching the band-edge states. Excitation intensity dependent measurements indicate that those charge carriers which contribute to the band-edge absorption bleaching also contribute proportionally to the time-integrated PL spectrum.

AB - Femtosecond transient absorption spectroscopy has been used together with time-integrated photoluminescence (PL) measurements to study charge carrier relaxation in colloidal InP quantum dots (QDs). Measurements of band-edge photoinduced bleaching as well as PL intensity measurements indicate that the fraction of charge carriers relaxing to the band-edge states depends on excitation wavelength, with a markedly reduced relaxation efficiency observed for excitation well above the absorption edge. The results concur with previous research on CdSe and InP QDs, and suggest that with increasing excitation energy there arise relaxation pathways involving surface or external energy states exhibiting reduced radiative efficiency. Such highly excited carriers are either inhibited or deviated from reaching the band-edge states. Excitation intensity dependent measurements indicate that those charge carriers which contribute to the band-edge absorption bleaching also contribute proportionally to the time-integrated PL spectrum.

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Excitation Energy Dependent Efficiency of Charge Carrier Relaxation and Photoluminescence in Colloidal InP Quantum Dots

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