In-situ spontaneous emission control of MoSe$_2$-WSe$_2$ interlayer excitons with near-unity quantum yield

TL;DR

This study demonstrates in-situ control of interlayer exciton emission in MoSe$_2$-WSe$_2$ heterostructures using an open optical microcavity, achieving near-unity quantum yield and significant emission inhibition, advancing quantum optoelectronics.

Contribution

We introduce a method to dynamically tune and inhibit interlayer exciton emission in van-der-Waals heterostructures using a tunable open microcavity and Tamm-plasmon resonances.

Findings

Interlayer exciton lifetime can be periodically tuned with 110 ps amplitude.

Quantum efficiency of interlayer excitons reaches up to 81%.

Spontaneous emission can be inhibited by a factor of 3.2.

Abstract

Optical resonators are a powerful platform to control the spontaneous emission dynamics of excitons in solid-state nanostructures. Here, we study a MoSe$_2$-WSe$_2$ van-der-Waals heterostructure that is integrated in a widely tunable open optical microcavity to gain insights into fundamental optical properties of the emergent interlayer charge-transfer excitons. First, we utilize an ultra-low quality factor open planar vertical cavity and investigate the modification of the excitonic lifetime as on- and off-resonant conditions are met with consecutive longitudinal modes. Time-resolved photoluminescence measurements reveal that the interlayer exciton lifetime can thus be periodically tuned with an amplitude of 110 ps. The resulting oscillations of the interlayer exciton lifetime allows us to extract a 0.5 ns free-space radiative lifetime and a quantum efficiency as high as 81 \%. We subsequently engineer the local density of optical states by introducing a spatially confined and fully spectrally tunable Tamm-plasmon resonance. The dramatic redistribution of the local optical modes in this setting allows us to encounter a profound inhibition of spontaneous emission of the interlayer excitons by a factor of 3.2. We expect that specifically engineering the inhibition of radiation from moir\'e excitons is a powerful tool to steer their thermalization, and eventually their condensation into coherent condensate phases.