Dipolar interlayer excitons in transition metal dichalcogenide alloy heterobilayers

Abstract Interlayer excitons in transition metal dichalcogenide (TMD) heterobilayers possess a permanent electric dipole moment and long recombination lifetimes, making them a promising platform for exploring excitonic many-body physics. Here, we report dipolar interlayer excitons in a MoS _1.4 Se _0.6 /MoSe ₂ heterobilayer encapsulated in hexagonal boron nitride. Low-temperature photoluminescence measurements reveal a distinct emission peak at ∼ 1.4 eV, attributed to radiative recombination of interlayer excitons. The emission exhibits a blueshift with increasing excitation power, indicating repulsive dipole-dipole interactions. Time-resolved photoluminescence measurements uncover nanosecond-scale lifetimes, consistent with the spatial separation of electrons and holes across the two layers. These findings establish chalcogen-alloyed TMD heterobilayers as a versatile platform for engineering dipolar excitons and tuning excitonic interactions in van der Waals materials.