Chiral-induced circularly polarized light emission from a single-molecule junction

TL;DR

This paper theoretically demonstrates that a biased single-molecule junction with a chiral helical bridge can emit circularly polarized light, with the polarization handedness controlled by bias direction and voltage, independent of magnetic or spin-orbit effects.

Contribution

It introduces a novel mechanism for chiral-induced circularly polarized light emission in single-molecule junctions based on chiral properties and bias distribution.

Findings

Circularly polarized light emission depends on bias polarity and direction.

Emission mechanism is independent of magnetic moments and spin-orbit interactions.

The chiral bridge's properties control the polarization of emitted light.

Abstract

In the present work we theoretically analyze electroluminescence occurring in a biased single-molecule junction with a chiral bridge imitated by a helical chain. We show that optical transitions between electron states of the chiral linker may result in the emission of circular polarized light whose handedness depends on both direction of propagation and the polarity of the bias voltage provided that the coupling between the bridge sites is sufficiently strong. The mechanism controlling this specific light emission does not depend on the magnetic moments and spin-orbit interactions. It rather relies on the chiral properties of the bridge molecule and on the distribution of the bias voltage between the electrodes in the junction.