Fluorescence intermittency originates from reclustering in two-dimensional organic semiconductors

Area of Science:

• Materials Science
• Nanotechnology
• Photochemistry

Background:

• Fluorescence intermittency (blinking) is common in nanoscale fluorophores, showing power-law distributions and 1/f noise.
• Blinking has been observed in 0D, 1D, and 2D systems, including reduced graphene oxide.
• The causes of blinking in reduced graphene oxide, particularly during photoreduction, remain unclear.

Purpose of the Study:

• To investigate the underlying mechanisms of fluorescence intermittency during graphene oxide photoreduction.
• To establish a causal link between chemical reactions and blinking behavior in reduced graphene oxide.
• To model the photochemistry and emission dynamics of reduced graphene oxide.

Main Methods:

• Utilized multiscale modeling to simulate reduced graphene oxide's absorption and emission.
• Connected simulation results to the photochemistry of graphene oxide reduction.
• Analyzed the redistribution and reclustering of carbon sp² domains.

Main Results:

• Fluorescence blinking in reduced graphene oxide is primarily due to the redistribution of carbon sp² domains.
• Reclustering of these domains causes fluctuations in emissive nanocluster size and number.
• Multiscale modeling successfully captured experimental emission trajectories and linked them to reduction photochemistry.

Conclusions:

• The study establishes causality between chemical reactions (sp² domain redistribution) and long-timescale emission intermittency in reduced graphene oxide.
• Identified specific chemical reactions responsible for switching between on and off fluorescence states.
• Provided a mechanistic understanding of blinking in this quantum mechanical fluorophore.