Dielectric Screening of Excitons and Trions in Single-Layer MoS2

Nano Lett. 2014 Oct 8;14(10):5569-76. doi: 10.1021/nl501988y. Epub 2014 Sep 19.

Abstract

Photoluminescence (PL) properties of single-layer MoS2 are indicated to have strong correlations with the surrounding dielectric environment. Blue shifts of up to 40 meV of exciton or trion PL peaks were observed as a function of the dielectric constant of the environment. These results can be explained by the dielectric screening effect of the Coulomb potential; based on this, a scaling relationship was developed with the extracted electronic band gap and exciton and trion binding energies in good agreement with theoretical estimations. It was also observed that the trion/exciton intensity ratio can be tuned by at least 1 order of magnitude with different dielectric environments. Our findings are helpful to better understand the tightly bound exciton properties in strongly quantum-confined systems and provide a simple approach to the selective and separate generation of excitons or trions with potential applications in excitonic interconnects and valleytronics.

Keywords: Transition metal dichalcogenides; binding energy; dielectric screening; exciton; molybdenum disulfide; photoluminescence.

Publication types

  • Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

  • Disulfides / chemistry*
  • Electric Conductivity
  • Luminescence
  • Luminescent Agents / chemistry*
  • Molybdenum / chemistry*
  • Quantum Theory
  • Solvents / chemistry

Substances

  • Disulfides
  • Luminescent Agents
  • Solvents
  • Molybdenum
  • molybdenum disulfide