Nonmonotonic size dependence in the hole mobility of methoxide-stabilized PbSe quantum dot solids

Marcus Scheele, Jesse H. Engel, Vivian E. Ferry, David Hanifi, Yi Liu, A. Paul Alivisatos

Research output: Contribution to journalArticlepeer-review

25 Scopus citations

Abstract

We present a facile procedure to fabricate p-type PbSe-based quantum dot solids with mobilities as large as 0.3 cm2 V-1s -1. Upon partial ligand exchange of oleate-capped PbSe quantum dots with the methoxide ion, we observe a pronounced red shift in the excitonic transition in conjunction with a large increase in conductivity. We show that there is little correlation between these two phenomena and that the electronic coupling energy in PbSe quantum dot solids is much smaller than often assumed. However, we observe for the first time a nonmonotonic size dependence of the hole mobility, illustrating that coupling can nonetheless be dominant in determining the transport characteristics. We attribute these effects to a decrease in charging energy and interparticle spacing, leading to enhanced electronic coupling on one hand and enhanced dipole interactions on the other hand, which is held responsible for the majority of the red shift.

Original languageEnglish (US)
Pages (from-to)6774-6781
Number of pages8
JournalACS nano
Volume7
Issue number8
DOIs
StatePublished - Aug 27 2013

Keywords

  • coupling
  • electrical transport
  • optical properties
  • quantum dot solids

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