Room temperature wavelike exciton transport in a van der Waals superatomic semiconductor

TL;DR

This paper demonstrates room-temperature wavelike exciton transport in a van der Waals superatomic semiconductor, revealing quasi-ballistic propagation of acoustic exciton-polarons that surpasses traditional semiconductors in energy transport efficiency.

Contribution

It introduces the formation and direct imaging of acoustic exciton-polarons in Re6Se8Cl2, showing their ballistic transport at room temperature, a novel phenomenon in vdW semiconductors.

Findings

Quasi-ballistic, wavelike exciton-polaron transport observed at room temperature.

Transport distances extend several microns over nanoseconds.

Transport efficiency exceeds that of silicon in similar conditions.

Abstract

The transport of energy and information in semiconductors is limited by scattering between electronic carriers and lattice phonons, resulting in diffusive and lossy transport that curtails all semiconductor technologies. Using Re6Se8Cl2, a van der Waals (vdW) superatomic semiconductor, we demonstrate the formation of acoustic exciton-polarons, an electronic quasiparticle shielded from phonon scattering. We directly image polaron transport in Re6Se8Cl2 at room temperature and reveal quasi-ballistic, wavelike propagation sustained for nanoseconds and several microns. Shielded polaron transport leads to electronic energy propagation orders of magnitude greater than in other vdW semiconductors, exceeding even silicon over nanoseconds. We propose that, counterintuitively, quasi-flat electronic bands and strong exciton-acoustic phonon coupling are together responsible for the remarkable transport properties of Re6Se8Cl2, establishing a new path to ballistic room-temperature semiconductors.