Measuring Charge Carrier Diffusion in Coupled Colloidal Quantum Dot Solids

Handle URI:
http://hdl.handle.net/10754/598782
Title:
Measuring Charge Carrier Diffusion in Coupled Colloidal Quantum Dot Solids
Authors:
Zhitomirsky, David; Voznyy, Oleksandr; Hoogland, Sjoerd; Sargent, Edward H.
Abstract:
Colloidal quantum dots (CQDs) are attractive materials for inexpensive, room-temperature-, and solution-processed optoelectronic devices. A high carrier diffusion length is desirable for many CQD device applications. In this work we develop two new experimental methods to investigate charge carrier diffusion in coupled CQD solids under charge-neutral, i.e., undepleted, conditions. The methods take advantage of the quantum-size-effect tunability of our materials, utilizing a smaller-bandgap population of quantum dots as a reporter system. We develop analytical models of diffusion in 1D and 3D structures that allow direct extraction of diffusion length from convenient parametric plots and purely optical measurements. We measure several CQD solids fabricated using a number of distinct methods and having significantly different doping and surface ligand treatments. We find that CQD materials recently reported to achieve a certified power conversion efficiency of 7% with hybrid organic-inorganic passivation have a diffusion length of 80 ± 10 nm. The model further allows us to extract the lifetime, trap density, mobility, and diffusion coefficient independently in each material system. This work will facilitate further progress in extending the diffusion length, ultimately leading to high-quality CQD solid semiconducting materials and improved CQD optoelectronic devices, including CQD solar cells. © 2013 American Chemical Society.
Citation:
Zhitomirsky D, Voznyy O, Hoogland S, Sargent EH (2013) Measuring Charge Carrier Diffusion in Coupled Colloidal Quantum Dot Solids. ACS Nano 7: 5282–5290. Available: http://dx.doi.org/10.1021/nn402197a.
Publisher:
American Chemical Society (ACS)
Journal:
ACS Nano
KAUST Grant Number:
KUS-11-009-21
Issue Date:
25-Jun-2013
DOI:
10.1021/nn402197a
PubMed ID:
23701285
Type:
Article
ISSN:
1936-0851; 1936-086X
Sponsors:
This publication is based in part on work supported by Award KUS-11-009-21, made by King Abdullah University of Science and Technology (KAUST), by the Ontario Research Fund Research Excellence Program, and by the Natural Sciences and Engineering Research Council (NSERC) of Canada. David Zhitomirsky would like to acknowledge his NSERC CGS D scholarship. We thank Angstrom Engineering, Inc. and Innovative Technology, Inc. for useful discussions regarding material deposition methods and control of the glovebox environment, respectively. The authors would like to acknowledge P. Maraghechi for aid in ellipsometry measurements and technical assistance from E. Palmiano, R. Wolowiec, and D. Kopilovic.
Appears in Collections:
Publications Acknowledging KAUST Support

Full metadata record

DC FieldValue Language
dc.contributor.authorZhitomirsky, Daviden
dc.contributor.authorVoznyy, Oleksandren
dc.contributor.authorHoogland, Sjoerden
dc.contributor.authorSargent, Edward H.en
dc.date.accessioned2016-02-25T13:41:07Zen
dc.date.available2016-02-25T13:41:07Zen
dc.date.issued2013-06-25en
dc.identifier.citationZhitomirsky D, Voznyy O, Hoogland S, Sargent EH (2013) Measuring Charge Carrier Diffusion in Coupled Colloidal Quantum Dot Solids. ACS Nano 7: 5282–5290. Available: http://dx.doi.org/10.1021/nn402197a.en
dc.identifier.issn1936-0851en
dc.identifier.issn1936-086Xen
dc.identifier.pmid23701285en
dc.identifier.doi10.1021/nn402197aen
dc.identifier.urihttp://hdl.handle.net/10754/598782en
dc.description.abstractColloidal quantum dots (CQDs) are attractive materials for inexpensive, room-temperature-, and solution-processed optoelectronic devices. A high carrier diffusion length is desirable for many CQD device applications. In this work we develop two new experimental methods to investigate charge carrier diffusion in coupled CQD solids under charge-neutral, i.e., undepleted, conditions. The methods take advantage of the quantum-size-effect tunability of our materials, utilizing a smaller-bandgap population of quantum dots as a reporter system. We develop analytical models of diffusion in 1D and 3D structures that allow direct extraction of diffusion length from convenient parametric plots and purely optical measurements. We measure several CQD solids fabricated using a number of distinct methods and having significantly different doping and surface ligand treatments. We find that CQD materials recently reported to achieve a certified power conversion efficiency of 7% with hybrid organic-inorganic passivation have a diffusion length of 80 ± 10 nm. The model further allows us to extract the lifetime, trap density, mobility, and diffusion coefficient independently in each material system. This work will facilitate further progress in extending the diffusion length, ultimately leading to high-quality CQD solid semiconducting materials and improved CQD optoelectronic devices, including CQD solar cells. © 2013 American Chemical Society.en
dc.description.sponsorshipThis publication is based in part on work supported by Award KUS-11-009-21, made by King Abdullah University of Science and Technology (KAUST), by the Ontario Research Fund Research Excellence Program, and by the Natural Sciences and Engineering Research Council (NSERC) of Canada. David Zhitomirsky would like to acknowledge his NSERC CGS D scholarship. We thank Angstrom Engineering, Inc. and Innovative Technology, Inc. for useful discussions regarding material deposition methods and control of the glovebox environment, respectively. The authors would like to acknowledge P. Maraghechi for aid in ellipsometry measurements and technical assistance from E. Palmiano, R. Wolowiec, and D. Kopilovic.en
dc.publisherAmerican Chemical Society (ACS)en
dc.subjectcolloidal quantum dotsen
dc.subjectdiffusion lengthen
dc.subjectlifetimeen
dc.subjectmobilityen
dc.subjecttransporten
dc.titleMeasuring Charge Carrier Diffusion in Coupled Colloidal Quantum Dot Solidsen
dc.typeArticleen
dc.identifier.journalACS Nanoen
dc.contributor.institutionUniversity of Toronto, Toronto, Canadaen
kaust.grant.numberKUS-11-009-21en

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