Facet-Dependent Electrical Conductivity Properties of PbS Nanocrystals

Chih-Shan Tan, Hsiang Sheng Chen, Chun Ya Chiu, Szu Chieh Wu, Lih-Juann Chen, Michael H. Huang*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

38 Scopus citations

Abstract

Large PbS protruded cubes, edge- A nd corner-truncated cubes and octahedra, and perfect octahedra with sizes over 200 nm have been synthesized in aqueous solution. By using two surface oxide-free tungsten probes to contact a clean particle, these PbS nanocrystals displayed facet-dependent electrical conductivity behaviors. Both {110} and {100} faces are highly conductive at applied voltages beyond 4 V, but the {111} faces can remain nonconductive even at 5 V. An asymmetric I-V curve was recorded when electrical contacts were made simultaneously on the {110} and {111} facets of a truncated cube. A modified band diagram of PbS is constructed to account for the observed facet-dependent effect. Density of states plots for varying numbers of PbS surface planes show larger areas of conduction band electron occupancy for the (110) and (100) planes than that for the (111) planes at a layer thickness of 3.0-3.4 nm. The work represents that, for the first time, the facet-dependent electrical properties of an n-type semiconductor nanocrystal are directly probed. Facet-dependent electrical conductivity should be a general semiconductor property and can be exploited to fabricate single-nanocrystal operating electronic components.
Original languageEnglish
Pages (from-to)1574-1580
Number of pages7
JournalChemistry of Materials
Volume28
Issue number5
DOIs
StatePublished - 8 Mar 2016

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