Excitonic Landscape and Phonon-Mediated Recombination in Moiré-Engineered Twisted WSe<sub>2</sub> Bilayers.

Thapa, Memansa; Thomas, Aksa; U J, Jayalekshmi; Bera, Krishna Prasad; Solanki, Darshit; Watanabe, Kenji; Taniguchi, Takashi; Shukla, Ajay Kumar et al. · Nano Lett · 2026

basic_science · Level V

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Abstract

Twist-angle engineering in two-dimensional (2D) van der Waals (vdW) heterostructures unlocks an additional degree of freedom to tune optoelectronic properties and probe multibody quantum interactions. Here, we report light emission from the moiré superlattice of a twisted bilayer of tungsten diselenide (WSe<sub>2</sub>/WSe<sub>2</sub>) encapsulated in insulating hexagonal boron nitride (hBN). The low-temperature photoluminescence (PL) spectroscopy reveals signatures of moiré-potential-induced strong interlayer excitonic emission and phonon-assisted recombinations, while the twisting significantly suppresses the emission from localized defect-bound excitons. The moiré potential redistributes carriers into indirect valleys, thereby enhancing recombination efficiency and stabilizing the interlayer excitons. Our findings establish that specific control of twist angle and dielectric environment provides a new route for engineering excitonic systems to explore exciton-phonon interactions and associated quantum phenomena in transition-metal dichalcogenides.