Observation of double indirect interlayer exciton in MoSe₂/WSe₂ heterostructure

Interlayer excitons (IX_S) are electron–hole pairs bound in the spatial separation layer by the Coulomb effect, and their lifetime is several orders of magnitude longer than that of direct excitons, providing an essential platform for long-lived exciton devices. The recent emergence of the van der Waals heterostructure (HS), which combines two layers of different transitional metal dichalcogenides (TMDs), has created new opportunities for IX research. Herein, we demonstrate the observation of double indirect interlayer excitons in the MoSe₂/WSe₂ HS using photoluminescence (PL) spectroscopy. The intensities of the two peaks are essentially the same, and the energy difference is 22 meV, which is perfectly in line with the calculation result of density functional theory. Furthermore, the experience of variable excitation power also proves that the splitting of the IXs originates from the conduction band spin-splitting of MoSe₂. The observation results provide a promising platform for further exploring the new physical properties and optoelectronic phenomena of TMD HS.