Newly observed temperature and surface ligand dependence of electron mobility in indium oxide nanocrystals solids.

We developed a new class of organic surface ligands; 2-aminopyridine (2AP), 4-aminobenzoic acid (4ABA), and benzoic acid (BA); for use in the solution ligand exchange of nanocrystals (NCs) in the presence of nitric acid (HNO3). Here, colloidal NCs synthesis is used for the first time. These short, air-stable, easy-to-model ligands bind to the surface of the indium oxide nanocrystal (In2O3 NC) and provide the electrostatic stabilization of NC semiconductor dispersions in N,N-dimethylformamide, allowing for a solution-based deposition of NCs into thin-film transitors (TFTs). The shorter organic ligands greatly facilitate electronic coupling between the NCs. For example, thin films made from 2AP-capped In2O3 NCs exhibited a high electron mobility of μ ≈ 9.5 cm2/(V·s), an on–off current ratio of about >107, and a subthreshold swing of 2.34 V/decade. As the ligand length decreased, the electron mobility increased exponentially. Furthermore, we also report on the temperature-dependent behavior of the electron t...