Layer-Number Engineered Momentum-Indirect Interlayer Excitons with Large Spectral Tunability

Interlayer excitons (IXs) in type II van der Waals (vdW) heterostructures are equipped with an oriented permanent dipole moment and long lifetime and thus would allow promising applications in excitonic and optoelectronic devices. However, based on the widely studied heterostructures of transition-metal dichalcogenides (TMDs), IX emission is greatly influenced by the lattice mismatch and geometric misalignment between the constituent layers, increasing the complexity of the device fabrication. Here, we report on the robust momentum-indirect IX emission in TMD/two-dimensional (2D) perovskite vdW heterostructures, which were fabricated without considering the orientation arrangement or momentum mismatch. The IXs show a large diffusion coefficient of similar to 10 cm(2) s(-1), and importantly the IX emission energy can be widely tuned from 1.3 to 1.6 eV via changing the layer number of the 2D perovskite or the thickness of TMD flakes, shedding light on the applications of vdW interface engineering to broad-spectrum optoelectronics.

Automated summary

This study reports on a type of robust interlayer excitons emission in two-dimensional perovskite/transition-metal dichalcogenide heterostructures. Unlike the existing research, this heterostructure was fabricated without considering orientation arrangement or momentum mismatch. The interlayer excitons in this structure exhibit a large diffusion coefficient, and the emission energy can be tuned by varying the layer number of the perovskite or the thickness of the dichalcogenide flakes.