Robust Interlayer Exciton Interplay in Twisted van der Waals Heterotrilayer on a Broadband Bragg Reflector up to Room Temperature

TL;DR

This study demonstrates the creation of a heterotrilayer van der Waals structure with stable, tunable interlayer excitons at room temperature, enhanced by a Bragg reflector, advancing excitonic optoelectronics and quantum photonics.

Contribution

It introduces a novel heterotrilayer platform with engineered stacking and optical enhancement, enabling stable interlayer excitons from cryogenic to room temperature.

Findings

Tenfold photoluminescence enhancement at cryogenic temperatures

Sevenfold increase in exciton decay time compared to heterobilayer

Room temperature stability of valley-polarized interlayer excitons

Abstract

We report robust room temperature interlayer excitons in transition metal dichalcogenide heterostructures engineered via precise stacking orientation and twist-angle control. We integrate 2H-stacked MoSe$_{2}$/$^{1}$WSe$_{2}$/$^{2}$WSe$_{2}$ heterotrilayer onto a chirped distributed Bragg reflector that acts as a backside mirror. This way, we fabricate a platform that hosts distinct heterotrilayer, heterobilayer, and homobilayer regions with enhanced excitonic features at elevated temperatures. Although the heterobilayer supports temperature-tunable singlet and triplet interlayer excitons, it exhibits low emission yield at 4 K. In comparison, the heterotrilayer shows remarkable excitonic properties, including pronounced band modulation, intervalley interlayer exciton transitions, and a tenfold photoluminescence enhancement along with a sevenfold increase in exciton decay time at cryogenic temperatures compared to the heterobilayer system. Temperature-dependent studies reveal intriguing interlayer exciton dynamics in the heterotrilayer, including the emergence of valley-polarized interlayer excitons, and the ability to maintain optical stability up to room temperature. Our results establish a clear strategy for engineering excitonic states across multilayer van der Waals heterostructures from 4 K to room temperature, providing a versatile platform for excitonic optoelectronics, quantum photonics, and tunable long-lived interlayer exciton states in scalable TMD heterostructures.