Monomolecular Membrane-Assisted Growth of Antimony Halide Perovskite/MoS2 Van der Waals Epitaxial Heterojunctions with Long-Lived Interlayer Exciton

Epitaxial growth stands as a key method for integrating semiconductors into heterostructures, offering a potent avenue to explore the electronic and optoelectronic characteristics of cutting-edge materials, such as transition metal dichalcogenide (TMD) and perovskites. Nevertheless, the layer-by-layer growth atop TMD materials confronts a substantial energy barrier, impeding the adsorption and nucleation of perovskite atoms on the 2D surface. Here, we epitaxially grown an inorganic lead-free perovskite on TMD and formed van der Waals (vdW) heterojunctions. Our work employs a monomolecular membrane-assisted growth strategy that reduces the contact angle and simultaneously diminishing the energy barrier for Cs₃Sb₂Br₉ surface nucleation. By controlling the nucleation temperature, we achieved a reduction in the thickness of the Cs₃Sb₂Br₉ epitaxial layer from 30 to approximately 4 nm. In the realm of inorganic lead-free perovskite and TMD heterojunctions, we observed long-lived interlayer exciton of 9.9 ns, approximately 36 times longer than the intralayer exciton lifetime, which benefited from the excellent interlayer coupling brought by direct epitaxial growth. Our research introduces a monomolecular membrane-assisted growth strategy that expands the diversity of materials attainable through vdW epitaxial growth, potentially contributing to future applications in optoelectronics involving heterojunctions.