Unraveling Dynamic Trap-State Modulation in Single Core-Crown CdSe/CdS Nanoplatelets

Area of Science:

• Materials Science
• Nanotechnology
• Quantum Dots

Background:

• Core-crown CdSe/CdS nanoplatelets offer enhanced quantum yield and optoelectronic properties.
• Their emission dynamics are significantly influenced by charge trapping phenomena.

Purpose of the Study:

• To investigate the emission dynamics of core-crown CdSe/CdS nanoplatelets.
• To understand the role of reversible charge trapping in luminescence.
• To identify distinct emission regimes and their underlying mechanisms.

Main Methods:

• Single-particle luminescence decay analysis.
• Correlation of luminescence decays with intensity fluctuations (blinking/flickering).
• Time-resolved spectroscopic analysis.

Main Results:

• A novel emission regime at intermediate brightness levels was identified, characterized by delayed luminescence.
• This delayed emission is attributed to a reversible charge trapping process.
• Stochastic switching between active and inactive reversible trapping states was observed within individual nanoplatelets.
• At higher excitation powers, non-radiative quenching pathways dominate over reversible trapping.

Conclusions:

• Reversible charge trapping plays a critical role in the emission dynamics of CdSe/CdS nanoplatelets.
• Understanding these trapping dynamics is crucial for optimizing their optoelectronic applications.
• The observed emission regimes provide insights into the fundamental photophysics of nanomaterials.