title: Newly observed temperature and surface ligand dependence of electron mobility in indium oxide nanocrystals solids.
abstract: 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 >10(7), 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 transport of In2O3 NCs films, in the case in which thin films were cured at 150 °C, as the 2AP, BA, and 4ABA ligand molecules were sustained on the NC. We demonstrated a hopping transport mechanism instead of a band-like transport, and the thermally activated carrier transport process governed the charge transport in our In2O3 NC thin-film solid.
authors.affiliation: Department of Chemistry, Chonnam National University, Gwangju 500-757, Republic of Korea.
authors.forename: Hien Thu
authors.initials: HT
authors.lastname: Pham
authors.affiliation: Department of Chemistry, Chonnam National University, Gwangju 500-757, Republic of Korea.
authors.forename: Hyun-Dam
authors.initials: HD
authors.lastname: Jeong
keywords: In2O3 nanocrystals; activation energy; ligand length dependence; temperature dependence; thermally activated carrier transport