Epitaxial Ag‐CsPbBr ₃ Perovskite Nanocrystal Heterostructures: Multi‐Facets Orientations, Suppressed Plasmon and Efficient Charge Transfer

Abstract Halide perovskite nanocrystals have been extensively studied for over a decade as an efficient optical material, exhibiting bright and tunable emissions. While various epitaxial perovskite heterostructures with other semiconductors or metals have been achieved, but epitaxial integration with plasmonic Ag or Au nanoparticles through facet‐specific connections has remained a key challenge. Keeping the importance of these nanocrystal heterostructures in mind, herein, we epitaxially integrated Ag nanoparticles with three different morphologies of CsPbBr 3 , each exhibiting one‐to‐one connections. The heterostructures were obtained by introducing Ag precursor either before or after CsPbBr 3 formation, depending on the reaction conditions. The feasibility of the synthesis is attributed to the presence of specific triangular and truncated facets having alternating Pb and Br atom arrangements in CsPbBr 3 . Electron microscopic analysis confirms two distinct epitaxial interfaces between cubic Ag(0) and orthorhombic CsPbBr 3, indicating the susceptibility of such nanocrystals to form heterostructures. Ultrafast spectroscopic data suggest the photoluminescence quenching arises from the photogenerated electron transfer from CsPbBr 3 to Ag. However, no significant plasmon absorption is observed, likely due to plasmon damping. These results provide new insight into plasmonic‐exciton coupling in this type of heterostructure and pave a pathway for designing other plasmonic material based heterostructures for optoelectronic applications.