Role of bond adaptability in the passivation of colloidal quantum dot solids

Susanna Thon, Alex Ip, Oleksandr Voznyy, Larissa Levina, Kyle W. Kemp, Graham H. Carey, Silvia Masala, E. H. Sargent

Research output: Contribution to journalArticlepeer-review

68 Scopus citations

Abstract

Colloidal quantum dot (CQD) solids are attractive materials for photovoltaic devices due to their low-cost solution-phase processing, high absorption cross sections, and their band gap tunability via the quantum size effect. Recent advances in CQD solar cell performance have relied on new surface passivation strategies. Specifically, cadmium cation passivation of surface chalcogen sites in PbS CQDs has been shown to contribute to lowered trap state densities and improved photovoltaic performance. Here we deploy a generalized solution-phase passivation strategy as a means to improving CQD surface management. We connect the effects of the choice of metal cation on solution-phase surface passivation, film-phase trap density of states, minority carrier mobility, and photovoltaic power conversion efficiency. We show that trap passivation and midgap density of states determine photovoltaic device performance and are strongly influenced by the choice of metal cation. Supported by density functional theory simulations, we propose a model for the role of cations, a picture wherein metals offering the shallowest electron affinities and the greatest adaptability in surface bonding configurations eliminate both deep and shallow traps effectively even in submonolayer amounts. This work illustrates the importance of materials choice in designing a flexible passivation strategy for optimum CQD device performance. © 2013 American Chemical Society.
Original languageEnglish (US)
Pages (from-to)7680-7688
Number of pages9
JournalACS Nano
Volume7
Issue number9
DOIs
StatePublished - Aug 12 2013

Bibliographical note

KAUST Repository Item: Exported on 2020-10-01
Acknowledged KAUST grant number(s): KUS-11-009-21
Acknowledgements: 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 M. Yuan, L Rollny, E. Palmiano, R. Wolowiec, and D. Kopilovic for their help during the course of the study. Computations were performed on the GPC supercomputer at the SciNet HPC Consortium. SciNet is funded by: the Canada Foundation for Innovation under the auspices of Compute Canada; the Government of Ontario; Ontario Research Fund Research Excellence; and the University of Toronto."

ASJC Scopus subject areas

  • General Physics and Astronomy
  • General Materials Science
  • General Engineering

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