Giant Enhancement of Photoluminescence and Optical Anisotropy in Monolayer MoSe ₂ via Energy Transfer

ABSTRACT Monolayer transition metal dichalcogenides (TMDs) exhibit great potentials in nanoscale optoelectronic applications due to their unique physical properties. Nevertheless, the limited amount of light absorption due to their ultrathin thickness of monolayers and the in‐plane optical anisotropy limit their applications in photonic devices and especially polarization‐resolved photonic devices. Here, we demonstrate giant enhancement of emission intensity and optical anisotropy of monolayer MoSe ₂ in ReS ₂ / h BN/MoSe ₂ heterostructures via Förster resonance energy transfer, in which multilayer ReS ₂ serves as the donor while monolayer MoSe ₂ as the acceptor, and the inserted multilayer h BN (≈11 nm) suppresses the charge transfer process. By tuning the thickness of ReS ₂ and thus the spectral overlapping between emission of multilayer ReS ₂ and absorption of monolayer MoSe ₂ , a ≈58.7‐fold photoluminescence (PL) enhancement can be achieved at room temperature. Importantly, accompanied by the energy transfer, the optical anisotropy of ReS ₂ can be successfully transferred to monolayer MoSe ₂ , resulting in a maximum linear dichroism of ≈1.86 in emission spectra. Furthermore, the energy transfer and optical anisotropy transfer between ReS ₂ and MoSe ₂ could subsequently pass over to interlayer excitons formed between MoSe ₂ and 2D perovskite in ReS ₂ / h BN/MoSe ₂ /2D perovskite heterostructures, leading to the enhanced anisotropic interlayer exciton emission that should be originally anisotropic in MoSe ₂ /2D perovskite heterostructures. Our study not only provides a practical avenue to improve the quantum efficiency of monolayer TMD‐based optoelectronic devices, but also offers new insights into the transfer of in‐plane optical anisotropy to the isotropic TMD monolayers for polarization‐associated photonic applications.