Amplification of interlayer exciton emission in twisted WSe2/WSe2/MoSe2 heterotrilayers

Abstract

Van der Waals heterostructures based on transition metal dichalcogenides exhibit physical properties that depend on their monolayer constituents’ twisting angle and stacking order. Particularly in type-II heterostructures, low-energy photoluminescence is dominated by interlayer excitons, resulting in low emission yields, which drastically hampers their optoelectronic applicability. This study reports on the photoluminescence quantum yield of heterostructures consisting of WSe2/WSe2/MoSe2 twisted layers. Our findings show that the additional WSe2 monolayer in the trilayer system enhances the low-energy photoluminescence by more than an order of magnitude depending on the WSe2/WSe2 twist-angle in comparison to their WSe2/MoSe2 heterobilayer counterpart. Furthermore, combining density functional theory calculations and extracted degree of circular polarization, we identify excitonic signatures arising from hybridized states that originate from the additional WSe2 layer. In addition to providing an additional understanding of hybridization effects in 2D semiconducting heterostructures, our findings provide a viable method to enhance emission in van der Waals heterostructures, relevant for studying the fundamental properties of excitons and enabling optoelectronic applications with high luminescence yield.