Influence of ligand exchange on the electrical transport properties of PbS nanocrystals

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Abstract

In this work, FETs are used as a research tool to study charge carrier mobilities in PbS nanocrystals (NCs) thin-films employed as semiconducting layer in bottom-gate bottom-contact (BGBC) field-effect transistors (FETs). The as-synthesised NCs are surrounded by long alkyl chain ligands which act as electrical insulators. Therefore, a ligand exchange process with shorter molecules is necessary to enhance the free charges generation and transport. We used two different ligands: 1,2 ethandithiol (EDT) and 1,2,3,4-tetrabutylammonium iodide (TBAI) and studied the charge mobility of PbS NCs comparing the electrical characteristics of FETs made by exchanged NCs. We analysed also the contemporary presence of both exchanged nanocrystals on the device. All the transistors showed p-type transport behaviour, enhanced by an annealing process at 100 °C for 10 min. After this, only the TBAI-treated NCs devices showed a n-type transport, resulting in an ambipolar behaviour. Inkjet printing deposition techniques was also successfully used to deposit PbS-(TBAI) NCs and ambipolar devices were obtained. In addition, for printed devices it was found that it is possible to modulate the charge transport properties by applying surface treatment to the substrate with a pentafluorothiophenol (PFTP). Indeed in this case, the p-type transport was suppressed while n-type behaviour was induced.
Original languageEnglish
Pages (from-to)2677 - 2685
Number of pages9
JournalPhysica Status Solidi (A) Applications and Materials Science
Volume212
Issue number12
DOIs
Publication statusPublished - 1 Dec 2015

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All Science Journal Classification (ASJC) codes

  • Electronic, Optical and Magnetic Materials
  • Condensed Matter Physics
  • Surfaces and Interfaces
  • Surfaces, Coatings and Films
  • Materials Chemistry
  • Electrical and Electronic Engineering

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