Single Semiconductor Nanocrystals under Compressive Stress: Reversible Tuning of the Emission Energy.
The photoluminescence of individual CdSe/CdS/ZnS core/shell nanocrystals has been investigated under external forces. After mutual alignment of a correlative atomic force and confocal microscope, individual particles were colocalized and exposed to a series of force cycles by using the tip of the AFM cantilever as a nanoscale piston. Thus, force-dependent changes of photophysical properties could be tracked on a single particle level. Remarkably, individual nanocrystals either shifted to higher or to lower emission energies with no indications of multiple emission lines under applied force. The direction and magnitude of these reversible spectral shifts depend on the orientation of nanocrystal axes relative to the external anisotropic force. Maximum pressures derived from the applied forces within a simple contact-mechanical model lie in the GPa range, comparable to values typically emerging in diamond anvil cells. Average spectral shift parameters of -3.5 meV/GPa and 3.0 meV/GPa are found for red- and blue-shifting species, respectively. Our results clearly demonstrate that the emission energy of single nanocrystals can be reversibly tuned over an appreciable wavelength range without degradation of their performance which appears as a promising feature with respect to tunable single photon sources or the creation of coherently coupled particle dimers.
Institute of Physical Chemistry, Johannes Gutenberg-University , Duesbergweg 10-14, 55128 Mainz, Germany.
Tobias
T
Fischer
Institute of Physical Chemistry, Johannes Gutenberg-University , Duesbergweg 10-14, 55128 Mainz, Germany.
Sven
S
Stöttinger
Institute of Physical Chemistry, Johannes Gutenberg-University , Duesbergweg 10-14, 55128 Mainz, Germany.
Gerald
0000-0003-4355-9325
G
Hinze
Institute of Physical Chemistry, Johannes Gutenberg-University , Duesbergweg 10-14, 55128 Mainz, Germany.
Anne
A
Bottin
Institute of Physical Chemistry, Johannes Gutenberg-University , Duesbergweg 10-14, 55128 Mainz, Germany.
Nan
N
Hu
Institute of Physical Chemistry, Johannes Gutenberg-University , Duesbergweg 10-14, 55128 Mainz, Germany.
Thomas
T
Basché
Core/shell nanocrystals; atomic force microscopy; confocal fluorescence microscopy; correlative microscopy