The study reports the observation of interlayer excitons in monolayer MoSe₂-WSe₂ heterostructures, which are constructed using van der Waals binding. These heterostructures, with type-II band alignment, feature bound electrons and holes localized in individual monolayers. The researchers used photoluminescence and photoluminescence excitation spectroscopy to observe the interlayer excitons, finding that their energy and luminescence intensity can be highly tunable by applying a vertical gate voltage. The interlayer exciton lifetime was measured to be approximately 1.8 ns, significantly longer than intralayer excitons in monolayers. The work demonstrates optical pumping of interlayer electric polarization, which could lead to further exploration of interlayer exciton condensation and new applications in two-dimensional lasers, light-emitting diodes, and photovoltaic devices.The study reports the observation of interlayer excitons in monolayer MoSe₂-WSe₂ heterostructures, which are constructed using van der Waals binding. These heterostructures, with type-II band alignment, feature bound electrons and holes localized in individual monolayers. The researchers used photoluminescence and photoluminescence excitation spectroscopy to observe the interlayer excitons, finding that their energy and luminescence intensity can be highly tunable by applying a vertical gate voltage. The interlayer exciton lifetime was measured to be approximately 1.8 ns, significantly longer than intralayer excitons in monolayers. The work demonstrates optical pumping of interlayer electric polarization, which could lead to further exploration of interlayer exciton condensation and new applications in two-dimensional lasers, light-emitting diodes, and photovoltaic devices.