Excitation Intensity-Dependent Quantum Yield of Semiconductor Nanocrystals

Area of Science:

• * Materials Science
• * Nanotechnology
• * Quantum Optics

Background:

• * Nonradiative Auger-Meitner recombination significantly impacts semiconductor nanocrystal fluorescence properties.
• * Accurate measurement of fluorescence quantum yield (QY) is challenging.
• * Understanding QY is crucial for optimizing nanocrystal applications.

Purpose of the Study:

• * To develop a method for determining absolute fluorescence quantum yield of nanocrystals.
• * To investigate the influence of excitation rate on nanocrystal quantum yield.
• * To leverage plasmonic nanocavities for precise control over radiative decay rates.

Main Methods:

• * Semiconductor nanocrystals were integrated into a tunable plasmonic nanocavity with subwavelength spacing.
• * The cavity size was adjusted to modulate the radiative de-excitation rate.
• * Absolute quantum yield was determined by correlating radiative rate changes with fluorescence properties.

Main Results:

• * The tunable plasmonic nanocavity enabled precise determination of absolute fluorescence quantum yield.
• * Increasing the excitation rate was found to decrease the nanocrystal quantum yield.
• * This reduction in QY is consistent with enhanced Auger-Meitner recombination at higher excitation levels.

Conclusions:

• * Plasmonic nanocavities offer a powerful tool for quantifying nanocrystal photophysical properties.
• * The study confirms the detrimental effect of high excitation rates on nanocrystal quantum yield.
• * Findings provide insights for designing efficient light-emitting nanocrystal systems.