Room temperature multi-phonon upconversion photoluminescence in monolayer semiconductor WS2

J. Jadczak,M. Bieniek,L. Bryja,Y.-S. Huang,J. Kutrowska-Girzycka,P. Kapuściński,P. Hawrylak

doi:10.1038/s41467-018-07994-1

Abstract

Photon upconversion is an anti-Stokes process in which an absorption of a photon leads to a reemission of a photon at an energy higher than the excitation energy. The upconversion photoemission has been already demonstrated in rare earth atoms in glasses, semiconductor quantum wells, nanobelts, carbon nanotubes and atomically thin semiconductors. Here, we demonstrate a room temperature upconversion photoluminescence process in a monolayer semiconductor WS2, with energy gain up to 150 meV. We attribute this process to transitions involving trions and many phonons and free exciton complexes. These results are very promising for energy harvesting, laser refrigeration and optoelectronics at the nanoscale.

Highlights

Photon upconversion is an anti-Stokes process in which an absorption of a photon leads to a reemission of a photon at an energy higher than the excitation energy
The upconversion photoemission has been already demonstrated in rare earth atoms in glasses[1,2,3], semiconductor quantum wells[4,5,6,7], nanobelts[8], carbon nanotubes[9] and atomically thin semiconductors[10,11] at cryogenic temperatures
The electrons in an excited state absorb phonons and are transferred to a higher energy excitonic state X, from which they recombine to the ground state, emitting a photon at an energy higher than the exciting laser photon energy

Summary

Introduction

Photon upconversion is an anti-Stokes process in which an absorption of a photon leads to a reemission of a photon at an energy higher than the excitation energy. We demonstrate a room temperature upconversion photoluminescence process in a monolayer semiconductor WS2, with energy gain up to 150 meV. We attribute this process to transitions involving trions and many phonons and free exciton complexes. The upconversion photoemission has been already demonstrated in rare earth atoms in glasses[1,2,3], semiconductor quantum wells[4,5,6,7], nanobelts[8], carbon nanotubes[9] and atomically thin semiconductors[10,11] at cryogenic temperatures. We show that the energy gain significantly depends on the temperature and increases from 42 meV at 7 K to 150 meV at 295 K

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Results

Conclusion