Fig. 1: Twisted ²WSe₂/¹WSe₂/MoSe₂ heterotrilayers.

a Schematic representation of the HTL system showcasing the stacking order and the substrate configuration along with potential interlayer and momentum-indirect exciton formation between the layers. b A simplified illustration of the HTL system (WSe₂ and MoSe₂ are shown in blue and green, respectively) showcasing complex moiré superlattices with the twist angle (θ_Bi and θ_HS) between the layers. Photoluminescence spectra for c HS1 and d HS2 measured at 4 K. The PL emission from the HTL (HBL) region is plotted in red (black) lines. The optical microscope images highlight the HBL and HTL regions with black and red outlines, respectively. The twist angle for the MoSe₂/WSe₂ heterostructure (θ_HS) in HS1 (HS2) is 44° (58°) and the twist angle for stacked WSe₂ MLs (θ_Bi) is close to 0° (57°). The inset in c, d shows the ratio of measured intensity from HTL and HBL regions (I_HTL/I_HBL) of both samples, demonstrating an enhancement factor of nearly 20 and ~3 for HS1 and HS2, respectively.