Excitation energy transfer from dye molecules to doped graphene

TL;DR

This paper investigates how energy transfer rates from dye molecules to doped graphene depend on distance and Fermi level shifts, revealing a crossover from a power-law to exponential decay.

Contribution

It introduces the effect of doping on energy transfer dynamics, showing a transition in distance dependence related to Fermi level shifts.

Findings

Energy transfer rate follows a $(distance)^{-4}$ dependence at low doping.

Increasing Fermi level shifts the rate to exponential decay.

Crossover occurs at Fermi level shift of $rac{ ext{h} u}{2}$.

Abstract

Recently, we have reported theoretical studies (J. Chem. Phys. 129, 054703, 2008 and J. Chem. Phys. 130, 086101, 2009) on the rate of energy transfer from an electronically excited molecule to graphene. It was found that graphene is a very efficient quencher of the electronically excited states and that the rate $\propto $ $(distance)^{-4}$. The process was found to be effective up to $30\;nm$ which is well beyond the traditional FRET limit. In this report, we study the transfer of an amount of energy $\hbar \Omega$ from a dye molecule to doped graphene. We find a crossover of the distance dependence of the rate from $(distance)^{-4}$ to exponential as the Fermi level is increasingly shifted into the conduction band, with the crossover occurring at a shift of the Fermi level by an amount $\hbar \Omega/2$.