Inhibited nonradiative decay at all exciton densities in monolayer semiconductors

Abstract

Most optoelectronic devices operate at high photocarrier densities, where all semiconductors suffer from enhanced nonradiative recombination. Nonradiative processes proportionately reduce photoluminescence (PL) quantum yield (QY), a performance metric that directly dictates the maximum device efficiency. Although transition-metal dichalcogenide (TMDC) monolayers exhibit near-unity PL QY at low exciton densities, nonradiative exciton-exciton annihilation (EEA) enhanced by van-Hove singularity (VHS) rapidly degrades their PL QY at high exciton densities and limits their utility in practical applications. Here, by applying small mechanical strain (< 1%), we circumvent VHS resonance and drastically suppress EEA in monolayer TMDCs, resulting in near-unity PL QY at all exciton densities despite the presence of a high native defect density. Our findings can enable light-emitting devices that retain high efficiency at all brightnesses.

References in corpus (3)

• Light-emitting diodes by bandstructure engineering in van der Waals heterostructures
• Electrical suppression of all nonradiative recombination pathways in monolayer semiconductors
• Directly visualizing the momentum forbidden dark excitons and their dynamics in atomically thin semiconductors

Cited by in corpus (6)

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• Excitonic beam steering in an active van der Waals metasurface
• Tuning exciton recombination rates in doped transition metaldichalcogenides
• The Importance of Pure Dephasing in the Optical Response of Excitons in High-quality van der Waals Heterostructures
• Possible structural and bond reconstruction in 2D ferromagnetic semiconductor VSe2 under uniaxial stress