Hybrid passivated colloidal quantum dot solids

Handle URI:
http://hdl.handle.net/10754/562250
Title:
Hybrid passivated colloidal quantum dot solids
Authors:
Ip, Alex; Thon, Susanna; Hoogland, Sjoerd H.; Voznyy, Oleksandr; Zhitomirsky, David; Debnath, Ratan K.; Levina, Larissa; Rollny, Lisa R.; Carey, Graham H.; Fischer, Armin H.; Kemp, Kyle W.; Kramer, Illan J.; Ning, Zhijun; Labelle, André J.; Chou, Kang Wei; Amassian, Aram ( 0000-0002-5734-1194 ) ; Sargent, E. H.
Abstract:
Colloidal quantum dot (CQD) films allow large-area solution processing and bandgap tuning through the quantum size effect. However, the high ratio of surface area to volume makes CQD films prone to high trap state densities if surfaces are imperfectly passivated, promoting recombination of charge carriers that is detrimental to device performance. Recent advances have replaced the long insulating ligands that enable colloidal stability following synthesis with shorter organic linkers or halide anions, leading to improved passivation and higher packing densities. Although this substitution has been performed using solid-state ligand exchange, a solution-based approach is preferable because it enables increased control over the balance of charges on the surface of the quantum dot, which is essential for eliminating midgap trap states. Furthermore, the solution-based approach leverages recent progress in metal:chalcogen chemistry in the liquid phase. Here, we quantify the density of midgap trap states in CQD solids and show that the performance of CQD-based photovoltaics is now limited by electrong-"hole recombination due to these states. Next, using density functional theory and optoelectronic device modelling, we show that to improve this performance it is essential to bind a suitable ligand to each potential trap site on the surface of the quantum dot. We then develop a robust hybrid passivation scheme that involves introducing halide anions during the end stages of the synthesis process, which can passivate trap sites that are inaccessible to much larger organic ligands. An organic crosslinking strategy is then used to form the film. Finally, we use our hybrid passivated CQD solid to fabricate a solar cell with a certified efficiency of 7.0%, which is a record for a CQD photovoltaic device. © 2012 Macmillan Publishers Limited. All rights reserved.
KAUST Department:
Physical Sciences and Engineering (PSE) Division; Materials Science and Engineering Program; Solar and Photovoltaic Engineering Research Center (SPERC); Organic Electronics and Photovoltaics Group
Publisher:
Springer Nature
Journal:
Nature Nanotechnology
Issue Date:
29-Jul-2012
DOI:
10.1038/nnano.2012.127
PubMed ID:
22842552
Type:
Article
ISSN:
17483387
Sponsors:
This publication is based in part on work supported by an award (KUS-11-009-21) from the 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. The authors thank Angstrom Engineering and Innovative Technology for useful discussions regarding material deposition methods and control of the glovebox environment, respectively. The Advanced Light Source is supported by the Director, Office of Science, Office of Basic Energy Sciences, of the US Department of Energy (contract no. DE-AC02-05CH11231). The authors thank L. Goncharova, M. T. Greiner, E. Palmiano, R. Wolowiec and D. Kopilovic for their help during the course of the study. A. H. I. acknowledges support from the Queen Elizabeth II Graduate Scholarship in Science and Technology. D. Z. acknowledges support from the NSERC CGS D scholarship.
Appears in Collections:
Articles; Physical Sciences and Engineering (PSE) Division; Materials Science and Engineering Program; Solar and Photovoltaic Engineering Research Center (SPERC)

Full metadata record

DC FieldValue Language
dc.contributor.authorIp, Alexen
dc.contributor.authorThon, Susannaen
dc.contributor.authorHoogland, Sjoerd H.en
dc.contributor.authorVoznyy, Oleksandren
dc.contributor.authorZhitomirsky, Daviden
dc.contributor.authorDebnath, Ratan K.en
dc.contributor.authorLevina, Larissaen
dc.contributor.authorRollny, Lisa R.en
dc.contributor.authorCarey, Graham H.en
dc.contributor.authorFischer, Armin H.en
dc.contributor.authorKemp, Kyle W.en
dc.contributor.authorKramer, Illan J.en
dc.contributor.authorNing, Zhijunen
dc.contributor.authorLabelle, André J.en
dc.contributor.authorChou, Kang Weien
dc.contributor.authorAmassian, Aramen
dc.contributor.authorSargent, E. H.en
dc.date.accessioned2015-08-03T09:58:02Zen
dc.date.available2015-08-03T09:58:02Zen
dc.date.issued2012-07-29en
dc.identifier.issn17483387en
dc.identifier.pmid22842552en
dc.identifier.doi10.1038/nnano.2012.127en
dc.identifier.urihttp://hdl.handle.net/10754/562250en
dc.description.abstractColloidal quantum dot (CQD) films allow large-area solution processing and bandgap tuning through the quantum size effect. However, the high ratio of surface area to volume makes CQD films prone to high trap state densities if surfaces are imperfectly passivated, promoting recombination of charge carriers that is detrimental to device performance. Recent advances have replaced the long insulating ligands that enable colloidal stability following synthesis with shorter organic linkers or halide anions, leading to improved passivation and higher packing densities. Although this substitution has been performed using solid-state ligand exchange, a solution-based approach is preferable because it enables increased control over the balance of charges on the surface of the quantum dot, which is essential for eliminating midgap trap states. Furthermore, the solution-based approach leverages recent progress in metal:chalcogen chemistry in the liquid phase. Here, we quantify the density of midgap trap states in CQD solids and show that the performance of CQD-based photovoltaics is now limited by electrong-"hole recombination due to these states. Next, using density functional theory and optoelectronic device modelling, we show that to improve this performance it is essential to bind a suitable ligand to each potential trap site on the surface of the quantum dot. We then develop a robust hybrid passivation scheme that involves introducing halide anions during the end stages of the synthesis process, which can passivate trap sites that are inaccessible to much larger organic ligands. An organic crosslinking strategy is then used to form the film. Finally, we use our hybrid passivated CQD solid to fabricate a solar cell with a certified efficiency of 7.0%, which is a record for a CQD photovoltaic device. © 2012 Macmillan Publishers Limited. All rights reserved.en
dc.description.sponsorshipThis publication is based in part on work supported by an award (KUS-11-009-21) from the 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. The authors thank Angstrom Engineering and Innovative Technology for useful discussions regarding material deposition methods and control of the glovebox environment, respectively. The Advanced Light Source is supported by the Director, Office of Science, Office of Basic Energy Sciences, of the US Department of Energy (contract no. DE-AC02-05CH11231). The authors thank L. Goncharova, M. T. Greiner, E. Palmiano, R. Wolowiec and D. Kopilovic for their help during the course of the study. A. H. I. acknowledges support from the Queen Elizabeth II Graduate Scholarship in Science and Technology. D. Z. acknowledges support from the NSERC CGS D scholarship.en
dc.publisherSpringer Natureen
dc.titleHybrid passivated colloidal quantum dot solidsen
dc.typeArticleen
dc.contributor.departmentPhysical Sciences and Engineering (PSE) Divisionen
dc.contributor.departmentMaterials Science and Engineering Programen
dc.contributor.departmentSolar and Photovoltaic Engineering Research Center (SPERC)en
dc.contributor.departmentOrganic Electronics and Photovoltaics Groupen
dc.identifier.journalNature Nanotechnologyen
dc.contributor.institutionUniv Toronto, Dept Elect & Comp Engn, Toronto, ON M5S 3G4, Canadaen
kaust.authorChou, Kang Weien
kaust.authorAmassian, Aramen

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