Related Experiment Video
Updated: Mar 15, 2026
13:39
Optical Trapping of Nanoparticles
Published on: January 15, 2013
23.0K
Sub-Picosecond Auger-Mediated Hole-Trapping Dynamics in Colloidal CdSe/CdS Core/Shell Nanoplatelets
Shuo Dong1, Sougata Pal2, Jie Lian3
1Division of Chemistry and Biological Chemistry, and Division of Physics and Applied Physics, School of Physical and Mathematical Sciences, Nanyang Technological University , 21 Nanyang Link, Singapore 637371.
ACS Nano
|September 20, 2016
Summary
Colloidal nanoplatelets exhibit rapid sub-picosecond carrier dynamics. Auger-mediated hole trapping and electron cooling occur on ultrafast timescales, influenced by surface trap states in these semiconductor nanomaterials.
Area of Science:
- Materials Science
- Nanotechnology
- Physical Chemistry
Background:
- Quasi-two-dimensional colloidal nanoplatelets (NPLs) offer precise thickness control for narrow optical spectra.
- Understanding ultrafast carrier dynamics in NPLs is crucial for their optoelectronic applications.
- Sub-picosecond carrier dynamics at the band edge of NPLs remain under-explored.
Purpose of the Study:
- Investigate early-time carrier dynamics in CdSe/CdS core/shell NPLs.
- Elucidate the mechanisms and timescales of carrier trapping and cooling.
- Correlate dynamics with surface properties using simulations.
Main Methods:
- Femtosecond transient absorption spectroscopy with band-selective probing.
- Nonadiabatic molecular dynamics (NAMD) simulations.
- Analysis of spectral shifts to infer carrier behavior.
Main Results:
- Observed sub-picosecond Auger-mediated hole trapping with a rate constant of 3.5 ± 1.0 cm²/s.
- Identified concomitant spectral blue shifts due to Auger hole heating on a sub-picosecond timescale.
- Determined an electron-cooling timescale of 0.84 ± 0.09 ps from spectral red shifts at low excitation densities.
Conclusions:
- Sub-picosecond Auger-mediated hole trapping is a dominant ultrafast process in CdSe/CdS NPLs.
- Shallow trap states, arising from incomplete surface passivation, are linked to observed hole-trapping dynamics.
- Carrier cooling and trapping dynamics are intrinsically linked to surface states in NPLs.
