Enhanced Hot-Carrier Luminescence in Multilayer Reduced Graphene Oxide Nanospheres

TL;DR

This study demonstrates that curling multilayer reduced graphene oxide into nanospheres significantly enhances hot-carrier luminescence by increasing carrier scattering, leading to over tenfold emission efficiency improvement.

Contribution

It introduces a novel method of forming graphene nanospheres to boost hot-carrier luminescence through enhanced carrier scattering without altering band structure.

Findings

Over tenfold increase in emission efficiency in nanospheres

Spectral redshift with increased excitation power

Enhanced electron-phonon coupling confirmed by experiments

Abstract

We report a method to promote photoluminescence emission in graphene materials by enhancing carrier scattering instead of directly modifying band structure in multilayer reduced graphene oxide (rGO) nanospheres. We intentionally curl graphene layers to form nanospheres by reducing graphene oxide with spherical polymer templates to manipulate the carrier scattering. These nanospheres produce hot-carrier luminescence with more than ten-fold improvement of emission efficiency as compared to planar nanosheets. With increasing excitation power, hot-carrier luminescence from nanospheres exhibits abnormal spectral redshift with dynamic feature associated to the strengthened electron-phonon coupling. These experimental results can be well understood by considering the screened Coulomb interactions. With increasing carrier density, the reduced screening effect promotes carrier scattering which enhances hot-carrier emission from such multilayer rGO nanospheres. This carrier-scattering scenario is further confirmed by pump-probe measurements.