Tuning the optical and electronic properties of colloidal nanocrystals by lattice strain

We have developed strain-tunable colloidal nanocrystals by using lattice-mismatched heterostructures that are grown by epitaxial deposition of a compressive shell onto a soft and small nanocrystalline core )

Andrew M. Smith; Aaron M. Mohs; Shuming Nie

2008

Scholarcy highlights

  • The impact of strain on materials is fundamentally important to a broad range of fields, from optoelectronics to biomechanics
  • Recent studies have explored the complex relationship between nanomaterials and strain, demonstrating that nanostructures with novel properties can be generated through lattice strain, and that nanomaterials respond differently to strain compared to their bulk counterparts
  • For II-VI semiconductors, it has been reported that CdS quantum dots have similar compressibilities compared to the bulk, whereas CdSe QDs are more compressible than the bulk material
  • We have reported a new class of core-shell quantum dots that are converted into type-II nanostructures by lattice strain
  • The growth temperature was set to 265°C and the final size of the colloidal type-II quantum dots such as QD core was controlled by varying the growth time, and by slow injection of additional precursors if larger sizes were desired
  • The strain-induced type-II behavior leads to a spatial separation of electrons and holes, and prolonged excited state lifetimes, parameters that will be important to multi-exciton generation and efficient solar energy conversion. Due to their near-infrared emission spectra and low cadmium content, this new class of compact quantum dots might be suitable for in-vivo animal imaging

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