The first single-sized (∼1 nm) and periodically ordered array of In2Te3 semiconductor quantum dots self-assembled in solution

Abstract

We report the first example of single-sized quantum dots (QD) of a III–VI semiconductor, In₂Te₃, self-assembled in solution. The nanometer-sized dots (∼1 nm in diameter) with the formula of In₈Te₁₂ are arranged into perfectly ordered arrays via an organic passivating and structure-directing molecule (triethylenetetramine or trien) resulting in a single crystal structure of [In₈Te₁₂(trien)₄] (monoclinic crystal system, space group C2/c). The In₈Te₁₂ dots in the [In₈Te₁₂(trien)₄] structure show a remarkably strong structure-induced quantum confinement effect which results in a very large blue shift of 2.1 eV in the optical absorption spectrum. The observed increase in the band gap is substantially higher than that of the smallest colloidal quantum dots reported to date. The In₈Te₁₂ dots are readily dispersible in suitable solvents to form nanoparticles of an average size of ∼8 to 10 nm. The capability of forming periodic crystal lattices of semiconductor quantum dots offers an attractive way to tune the electronic and optical properties in the same (or larger) extent as those of the smallest nanoparticles while having the advantages of precisely controlling the size and stoichiometry. Such a crystal assembly of QDs may find utility as a new type of molecular-based precursors for the fabrication of energy- and cost-effective solution-processed thin film devices.