Collective Fluorescence of Graphene Quantum Dots on a surface

TL;DR

This paper investigates how graphene quantum dots organize and exhibit collective fluorescence behavior on a perovskite surface, revealing aggregation, dynamic state transitions, and enhanced emission properties.

Contribution

It uncovers the aggregation tendency and collective fluorescence phenomena of graphene quantum dots on perovskite surfaces, a behavior not observed in solution or other substrates.

Findings

Graphene quantum dots tend to aggregate on perovskite surfaces.

Spectral analysis shows dynamic transitions between monomer-like and excimer states.

Collective emission leads to increased fluorescence intensity and shorter excited state lifetimes.

Abstract

This study explores the organization of graphene quantum dots on the surface of monocrystalline halide perovskite. We show that graphene quantum dots tends to aggregate on the surface of perovskite unlike in solution or on other substrates, even at very low concentration of the initial solution that should yield single-molecule samples. Spectral analysis on small clusters shows a back-and-forth dynamical transition between an uncoupled, monomer-like state, and an excimer state. Following this "dance" between states, a drastic one-way increase in fluorescence intensity combined with a shortening of the excited state lifetime has been observed on some clusters. This behavior is related to the emission of a collective state that may be a consequence of the dynamical organization of graphene quantum dots under illumination on the surface of the perovksite.