Manipulating the Self-Trapped Excitons in the Lead Iodide/Hexagonal Boron Nitride van der Waals Heterostructures

The self-trapped excitons (STEs) in soft van der Waals (vdW) materials have aroused tremendous attention. The conventional methods to manipulate the STEs include the introduction of permanent defect or lattice distortion, which lead to the suppression of the inherent structures and properties. Developing a non-destructive method to achieve room temperature STEs with high tunability is thus of strategic interest. Stacking 2D materials to form a vdW heterostructure will introduce many-body interactions, which should be exploited to tailor STE emissions controllably. To this regard, the highly tunable STE emissions in vdW heterostructures composed of lead iodide, hexagonal boron nitride, or molybdenum oxide are demonstrated. It is found that the synergistic effect of the dielectric screening and interfacial many-body interaction improve the temperature characteristic and emission properties of STEs. The strong STE emissions with highly tunable center energies in a broadband spectrum range from approximate to 625 to 750 nm are verified at room temperature. This work provides a non-destructive method to manipulate the STE emissions at room temperature in rigid lattice vdW materials, which is expected to open the potential of STEs for next-generation optoelectronics.