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The bright side of defects in MoS<sub>2</sub> and WS<sub>2</sub> and a generalizable chemical treatment protocol for defect passivation

ORAL

Abstract

Defects in transition metal dichalcogenides, such as MoS2 and WS2, are frequently considered responsible for quenching photoluminescence (PL) and lowering mobility, limiting many of the proposed applications. However, while many chemical treatments have been proposed to passivate defects, primarily assumed to be sulfur vacancies, the mechanism of this passivation is poorly understood. In this work, we illustrate how TFSI superacid treatment reveals an optical subgap state associated with sulfur vacancies. At room temperature, this subgap state contributes to enhanced quantum yields and lengthened emission lifetimes, compared to untreated samples, rather than quenching PL. Building on this understanding, we propose a generalizable treatment protocol to passivate defects in monolayer MoS2 and WS2, increasing photoluminescence and maintaining mobilities. This protocol opens up a route for solution-based, post-processing of samples, which could not only passivate defects, but also simultaneously tune properties and functionalize materials.

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Presenters

  • Hope Bretscher

    Department of Physics, University of Cambridge

Authors

  • Hope Bretscher

    Department of Physics, University of Cambridge

  • Zhaojun Li

    Department of Physics, University of Cambridge

  • James Xiao

    Department of Physics, University of Cambridge

  • Diana Qiu

    Department of Mechanical Engineering and Materials Science, Yale University, Physics, Unviersyt of Calfornia, Berkeley, Yale University, Mechanical Engineering and Materials Science, Yale University, University of California, Berkeley

  • Sivan Refaely-Abramson

    Department of Materials and Interfaces, Weizmann Institute of Science, Materials and Interfaces, Weizmann Institute of Science

  • Jack Alexander-Webber

    Department of Engineering, University of Cambridge

  • Arelo Tanoh

    Department of Physics, University of Cambridge

  • Ye Fan

    Department of Engineering, University of Cambridge

  • Geraud Delport

    Department of Physics, University of Cambridge

  • Cyan Williams

    Department of Chemistry, University of Cambridge

  • Silvia Vignolini

    Department of Chemistry, University of Cambridge, University of Cambridge

  • Sam Stranks

    Department of Chemical Engineering and Biotechnology, University of Cambridge, Department of Physics, University of Cambridge

  • Stephan Hofmann

    Department of Engineering, University of Cambridge

  • Steven Louie

    University of California at Berkeley, and Lawrence Berkeley National Laboratory, Department of Physics, University of California, Berkeley, Berkeley, California 94720, USA and Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, C, University of California, Berkeley, Department of Physics, University of California, Berkeley, Lawrence Berkeley National Laboratory and University of California at Berkeley, Department of Physics, University of California at Berkeley and Lawrence Berkeley National Laboratory, Department of Physics, UC Berkeley, Physics, Unviersyt of Calfornia, Berkeley, Physics, University of California, Berkeley, Physics, University of California, Berkeley and Lawrence Berkeley National Lab

  • Jeffrey Neaton

    University of California, Berkeley, Department of Physics, University of California, Berkeley

  • Akshay Rao

    Department of Physics, University of Cambridge, University of Cambridge, Cavendish Laboratory, Univ of Cambridge