Giant Enhancement of Photoluminescence Emission in Monolayer WS2 by Femtosecond Laser Irradiation

TL;DR

This paper demonstrates a significant enhancement of photoluminescence in monolayer WS2 using femtosecond laser irradiation, enabling stable microstructure creation with potential applications in optoelectronics.

Contribution

It introduces a femtosecond laser technique to drastically improve PL intensity and stability in monolayer WS2, surpassing previous methods in efficiency and longevity.

Findings

Over two orders of magnitude PL enhancement achieved

Engineering time reduced by three orders of magnitude

Created stable microstructures with long-term storage stability

Abstract

Monolayer transition metal dichalcogenides have emerged as promising materials for optoelectronic and nanophotonic devices. However, the low photoluminescence (PL) quantum yield (QY) hinders their various potential applications. Here we engineer and enhance the PL intensity of monolayer WS2 by femtosecond laser irradiation. More than two orders of magnitude enhancement of PL intensity as compared to the as-prepared sample is determined. Furthermore, the engineering time is shortened by three orders of magnitude as compared to the improvement of PL intensity by continuous-wave laser irradiation. Based on the evolution of PL spectra, we attribute the giant PL enhancement to the conversion from trion emission to exciton, as well as the improvement of the QY when exciton and trion are localized to the new-formed defects. We have created microstructures on the monolayer WS2 based on the enhancement of PL intensity, where the engineered structures can be stably stored for more than three years. This flexible approach with the feature of excellent long-term storage stability is promising for applications in information storage, display technology, and optoelectronic devices.