Architecture of Anisotropic One-Dimensional Gold-CsPbBr ₃ Perovskite Nanorod Epitaxial Heterostructure for Efficient Charge Separation

Epitaxial growth of metallic nanoparticles (NPs) over one-dimensional (1D) perovskite nanorods (NRs) is the key approach for attaining charge separation and tailoring their interfacial photophysical properties for efficient photovoltaic and photocatalytic devices. However, an epitaxial heterostructure (HS) comprising CsPbBr3 NRs and Au NPs (Au-CsPbBr3 HS) has not been successfully achieved yet owing to their challenging synthetic protocols and different chemical environments. Herein, we have synthesized an Au-CsPbBr3 HS through two-step cation exchange and chemical reduction methods by utilizing the Cs2CuBr4 NRs. High-resolution transmission electron microscopy demonstrates the successful epitaxial growth of Au NPs (8 nm) on CsPbBr3 NRs, facilitated by precise lattice matching between (111) and (024) planes. Steady-state optical absorption, photoluminescence (PL), and time-resolved PL studies provide evidence of charge transfer in the Au-CsPbBr3 HS. Further, transient absorption spectroscopy measurement results reveal efficient electron transfer (1.1 ps) from CsPbBr3 to the Au states and are further supported by density functional theory calculations. The facet-directive epitaxial growth, strong electronic coupling between the metal and perovskite states, and the enhanced density of states of Au NPs near the conduction band of CsPbBr3 NRs synergistically promote efficient electron transfer within the Au-CsPbBr3 HS. The enhnanced charge extraction highlights promising opportunities for developing next-generation photovoltaic and photocatalytic devices.