Article abstract
Nature Nanotechnology 4, 56 - 63 (2009)
Published online: 7 December 2008 | doi:10.1038/nnano.2008.360
Subject Categories: Electronic properties and devices | Nanoparticles | Organic-inorganic nanostructures | Photonic structures and devices
Tuning the optical and electronic properties of colloidal nanocrystals by lattice strain
Andrew M. Smith1, Aaron M. Mohs & Shuming Nie1
Abstract
Strain can have a large influence on the properties of materials at the nanoscale. The effect of lattice strain on semiconductor devices has been widely studied, but its influence on colloidal semiconductor nanocrystals is still poorly understood. Here we show that the epitaxial deposition of a compressive shell (ZnS, ZnSe, ZnTe, CdS or CdSe) onto a soft nanocrystalline core (CdTe) to form a lattice-mismatched quantum dot can dramatically change the conduction and valence band energies of both the core and the shell. In particular, standard type-I quantum-dot behaviour is replaced by type-II behaviour, which is characterized by spatial separation of electrons and holes, extended excited-state lifetimes and giant spectral shifts. Moreover, the strain induced by the lattice mismatch can be used to tune the light emission—which displays narrow linewidths and high quantum yields—across the visible and near-infrared part of the spectrum (500–1,050 nm). Lattice-mismatched core–shell quantum dots are expected to have applications in solar energy conversion, multicolour biomedical imaging and super-resolution optical microscopy.
- Departments of Biomedical Engineering and Chemistry, Emory University and Georgia Institute of Technology, 101 Woodruff Circle, Suite 2001, Atlanta, Georgia 30322, USA
Correspondence to: Shuming Nie1 e-mail: snie@emory.edu
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