Highly radiative emission of room temperature–localized excitons enabled by charge-neutralized 0D quantum wells in 2D semiconductors

TL;DR

Researchers developed a method to enable efficient light emission from localized excitons at room temperature using charge-neutralized quantum wells in 2D semiconductors.

Contribution

The novel approach involves using a charge-neutralized 0D quantum well to achieve high quantum yield in room-temperature exciton emission.

Findings

A drift-diffusion model confirmed ~98% exciton confinement efficiency.

Tip-induced pressure controls exciton dynamics and quantum yield reversibly.

Nanohole funneling enables bright localized exciton emission at the nanoscale.

Abstract

Nondiffusing localized excitons (XL) in two-dimensional semiconductors present a robust platform for mediating light-matter interactions, with potential applications in both photovoltaics and light-emitting devices. However, at room temperature, high thermal energy hinders XL formation, while excess charges diminish the quantum yield (QY) through nonradiative decay. Here, we present high-QY XL emission in ambient conditions by removing excess charges and inducing efficient exciton funneling into a Au nanohole. Specifically, by evaporating an H2O barrier between the n-type MoS2 and the Au substrate, we induce a grounding effect on electrons. Dominantly populating excitons are then funneled and bound to the nanohole through the strain-induced zero-dimensional quantum well effect. We confirm the exciton confinement efficiency of ~98% using a drift-diffusion model, enabling bright XL emission at the nanoscale. Using tip-induced gigapascal-scale pressure, we control XL dynamics and QY in a reversible manner. Our approach provides an innovative strategy for XL-based nanophotonic devices.

Charge-neutralized quantum wells enable highly efficient light emission from localized excitons at room temperature.

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