Measuring Ligand-Dependent Transport in Nanopatterned PbS Colloidal Quantum Dot Arrays Using Charge Sensing

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• 作者：Nirat Ray ; Neal E. Staley ; Darcy D. W. Grinolds ; Moungi G. Bawendi ; Marc A. Kastner
• 刊名：Nano Letters
• 出版年：2015
• 出版时间：July 8, 2015
• 年：2015
• 卷：15
• 期：7
• 页码：4401-4405
• 全文大小：283K
• ISSN：1530-6992

文摘

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 10¹⁸ 惟. We find that the conduction mechanism changes from nearest neighbor hopping in oleic-acid-capped PbS dots to Mott鈥檚 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.