Van der Waals (vdW) epitaxial growth provides an efficient strategy to prepare heterostructures with atomically and electronically sharp interfaces. Herein, PbI₂ was in situ thermally deposited onto exfoliated thin−layered CrOCl nanoflakes in high vacuum to fabricate vdW PbI₂/CrOCl heterostructures. Optical microscopy, atomic force microscopy, X−ray diffraction, and temperature−dependent Raman spectroscopy were used to investigate the structural properties and phonon behaviors of the heterostructures. The morphology of PbI₂ films on the CrOCl substrate obviously depended on the substrate temperature, changing from hemispherical granules to 2D nanoflakes with flat top surfaces. In addition, anomalous blueshift of the $A_g^1$ and $A_u^2$ modes as the temperature increased in PbI₂/CrOCl heterostructure was observed for the first time. Our results provide a novel material platform for the vdW heterostructure and a possible method for optimizing heterostructure growth behaviors.

Two-dimensional (2D) layered materials have received much attention due to the unique properties stemming from their van der Waals (vdW) interactions, quantum confinement, and many-body interactions of quasi-particles, which drive their exotic optical and electronic properties, making them critical in many applications. Here, we review our past years’ findings, focusing on many-body interactions in 2D layered materials, including phonon anharmonicity, electron–phonon coupling (e-ph), exciton dynamics, and phonon anisotropy based on temperature (polarization)-dependent Raman spectroscopy and Photoluminescence (PL). Our review sheds light on the role of quasi-particles in tuning the material properties, which could help optimize 2D materials for future applications in electronic and optoelectronic devices.