Mechanisms for charge trapping in single semiconductor nanocrystals probed by fluorescence blinking

Area of Science:

• Materials Science
• Physical Chemistry
• Nanotechnology

Background:

• Semiconductor nanocrystal properties are significantly affected by surface charge carrier trapping.
• Charge trapping diminishes fluorescence quantum yield and hinders charge transfer.
• This trapping leads to fluorescence intermittency, or blinking, at the single nanocrystal level.

Purpose of the Study:

• To review the relationship between charge trapping and fluorescence blinking in semiconductor nanocrystals.
• To introduce techniques for measuring single nanocrystal blinking.
• To discuss proposed blinking mechanisms and the nature of charge trapping sites.

Main Methods:

• Fluorescence microscopy techniques for single nanocrystal observation.
• Statistical analysis methods for quantifying blinking behavior.
• Review of experimental studies probing charge carrier trapping mechanisms.

Main Results:

• Charge trapping is directly linked to fluorescence blinking.
• Blinking experiments provide evidence for various charge trapping mechanisms.
• Changes in the nature and distribution of trapping sites can be monitored.

Conclusions:

• Fluorescence blinking is a key indicator of surface charge trapping in semiconductor nanocrystals.
• While the precise mechanism is still under investigation, blinking studies offer valuable insights.
• Understanding charge trapping is crucial for optimizing nanocrystal applications.