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arXiv · 2507.17879

Extending exciton and trion lifetimes in MoSe$_{2}$ with a nanoscale plasmonic cavity

Grace H. Chen·Anchita Addhya·Ian N. Hammock·Philip Kim·Alexander A. High
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Abstract

Excitons in transition metal dichalcogenides (TMDs) have extremely short, picosecond-scale lifetimes which hinders exciton thermalization, limits the emergence of collective coherence, and reduces exciton transport in optoelectronic devices. In this work, we explore an all-optical pathway to extend exciton lifetimes by placing MoSe$_2$ in a deep-subwavelength Fabry-Perot silver cavity. The cavity structure is designed to suppress radiative recombination from in-plane optical dipoles, such as bright excitons and trions. We observe a consistent decrease in photoluminescence (PL) linewidths of excitons and trions (~1 nm), along with a corresponding lifetime increase (~10 ps). We confirm the experimental observations arise purely from exciton-cavity interactions-etching back the top silver layer returns the PL linewidth and lifetimes return to their original values. Our study offers a pathway to engineer excited state lifetimes in 2D materials which can be utilized for studies of optically dark excitons and have potential applications for novel optoelectronic devices.

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Grace H. Chen, Anchita Addhya, Ian N. Hammock, Philip Kim, Alexander A. High. 2025-07-23. Extending exciton and trion lifetimes in MoSe$_{2}$ with a nanoscale plasmonic cavity. https://arxiv.org/abs/2507.17879

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