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

Susanna M. Thon, Alexander H. Ip, Oleksandr Voznyy, Larissa Levina, Kyle W. Kemp, Graham H. Carey, Silvia Masala, Edward H. Sargent*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

68 Scopus citations


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.

Original languageEnglish (US)
Pages (from-to)7680-7688
Number of pages9
JournalACS nano
Issue number9
StatePublished - Sep 24 2013


  • binding energy
  • colloidal quantum dots
  • DFT
  • PbS nanocrystals
  • photovoltaics
  • surface passivation

ASJC Scopus subject areas

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


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