Ligand-free ammonium sulfide-treated PbS nanocrystal field effect transistors

Abstract

We fabricated a ligand-free bare-PbS nanocrystal (NC) film and probed its electrical properties using field effect transistors (FETs). After the ligand removal process using ammonium sulfide (NH4)2S, the electrical conductivity of a PbS NC film was enhanced by three orders of magnitude in comparison with that of an ethanedithiol-treated PbS NC film. The origin of enhanced conductivity is addressed by increased carrier concentration in combination with enhanced electronic coupling. Quantum confinement in the bare PbS NCs was electrically addressed through size-dependent FET mobility measurements for 3nm and 5nm PbS NCs.