Configurational control of photon emission from a molecular dimer

TL;DR

This study investigates how the photon emission from a molecular dimer can be controlled by its configuration, revealing effects on luminescence intensity and spectral features through electrofluorescence measurements.

Contribution

It demonstrates configurational control over photon emission in a molecular dimer, showing how different arrangements significantly alter luminescence properties.

Findings

Photon yield varies with molecular configuration.

Dimer spectra show coupling of optical dipoles.

Luminescence is amplified or reduced depending on configuration.

Abstract

Tin-phthalocyanine molecules adsorbed on a NaCl ultrathin film on Au(111) exhibit electrofluorescence excited by a current across a scanning tunneling microscope junction. Exploring the dependence of the molecular monomer photon yield on the injected current evidences the one-electron excitation process underlying the neutral-exciton luminescence. Photon spectra of the monomer exhibit vibrational progression and hot luminescence, while the dimer electrofluorescence spectroscopic fine structure results from the coupling of the adjacent optical transition dipoles. The photon yield of the dimer is significantly altered upon changing the configurational state of one of the two molecules. In one of the bistable configurations light emission is amplified compared to the monomer, and it is reduced in the other.