title: Measuring Ligand-Dependent Transport in Nanopatterned PbS Colloidal Quantum Dot Arrays Using Charge Sensing.
abstract: Colloidal quantum dot arrays with long organic ligands have better packing order than those with short ligands but are highly resistive, making low-bias conductance measurements impossible with conventional two-probe techniques. We use an integrated charge sensor to study transport in weakly coupled arrays in the low-bias regime, and we nanopattern the arrays to minimize packing disorder. We present the temperature and field dependence of the resistance for nanopatterned oleic-acid and n-butylamine-capped PbS arrays, measuring resistances as high as 10(18) Ω. We find that the conduction mechanism changes from nearest neighbor hopping in oleic-acid-capped PbS dots to Mott's variable range hopping in n-butylamine capped PbS dots. Our results can be understood in terms of a change in the interdot coupling strength or a change in density of trap states and highlight the importance of the capping ligand on charge transport through colloidal quantum dot arrays.
authors.affiliation: †Department of Physics and ‡Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States.
authors.forename: Nirat
authors.initials: N
authors.lastname: Ray
authors.affiliation: †Department of Physics and ‡Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States.
authors.forename: Neal E
authors.initials: NE
authors.lastname: Staley
authors.affiliation: †Department of Physics and ‡Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States.
authors.forename: Darcy D W
authors.initials: DD
authors.lastname: Grinolds
authors.affiliation: †Department of Physics and ‡Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States.
authors.forename: Moungi G
authors.initials: MG
authors.lastname: Bawendi
authors.affiliation: †Department of Physics and ‡Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States.
authors.forename: Marc A
authors.initials: MA
authors.lastname: Kastner
keywords: PbS nanocrystals; electrical transport; nanopatterning; nanoscale charge sensor