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Optical and Electronic Properties of Colloidal CdSe Quantum Rings
James Xiao1, Yun Liu1, Violette Steinmetz1
1Cavendish Laboratory, University of Cambridge, J.J. Thomson Avenue, CB3 0HE, Cambridge, United Kingdom.
ACS Nano
|October 12, 2020
Summary
We studied luminescent cadmium selenide (CdSe) nanorings, revealing that their toroidal shape and surface traps significantly impact exciton properties and reduce light emission efficiency.
Area of Science:
- Semiconductor Nanomaterials
- Nanophotonics
- Quantum Dots
Background:
- Luminescent colloidal CdSe nanorings are novel semiconductor structures with potential for unique physics due to their toroidal shape.
- Understanding exciton properties and dynamics in these complex-topology materials is crucial but remains limited.
Purpose of the Study:
- To investigate the exciton properties and dynamics of CdSe nanorings.
- To elucidate the factors influencing their photoluminescence (PL) spectrum broadening and quantum yield reduction.
Main Methods:
- Femtosecond vibrational spectroscopy
- Temperature-resolved photoluminescence (PL) measurements
- Single-particle measurements
Main Results:
- Transformation from nanoplatelets to nanorings decreases emission lifetime and broadens the spectrum due to variations in ring dimensions.
- Reduced PL quantum yield in nanorings is linked to enhanced exciton-phonon coupling and selenium-rich trap sites.
- Surface charge of nanorings (∼-50 mV) and trap site population influence emission properties, especially at low temperatures.
Conclusions:
- Exciton behavior in CdSe nanorings is influenced by both toroidal shape and defects introduced during synthesis.
- Phonon coupling and surface charge play key roles in the observed spectral broadening and quantum yield losses.
- The findings offer insights into controlling light emission in complex nanostructures.
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