Long-Lived Interlayer Excitons in WS₂/Ruddlesden-Popper Perovskite van der Waals Heterostructures

Two-dimensional (2D) transition metal dichalcogenides (TMDs) and perovskites hold substantial promise for various optoelectronic applications such as light emission, photodetection, and energy harvesting. However, each of these materials possesses certain limitations that can be overcome by synergistically combining them to form heterostructures, thereby unveiling intriguing optical properties. In this study, we present an uncomplicated technique for crafting a van der Waals (vdW) heterojunction comprising monolayer WS₂ and a Ruddlesden-Popper (RP) perovskite, namely (TEA)₂PbI₄. By utilizing ultrafast transient absorption (TA) spectroscopy, we explored the charge carrier dynamics within the WS₂/(TEA)₂PbI₄ heterostructure. Our findings uncover a type-II band alignment in the heterostructure, facilitating rapid (within 260 fs) hole transfer from WS₂ to the perovskite and leading to the formation of interlayer excitons (IXs) with a much longer lifetime (728 ps). This strategic approach has the potential to contribute to the development of hybrid systems aimed at achieving high-performance optoelectronic devices.