Ultrafast Interfacial Charge Transfer in Anisotropic One-Dimensional CsPbBr₃/Pt Epitaxial Heterostructure

Colloidal one-dimensional (1D) perovskite nanorods (NRs) and metal epitaxial heterostructures (HSs) are the promising class of new materials for efficient photovoltaic and photocatalytic applications. Besides, fundamental photophysical properties and its device applications of 1D perovskite-metal HSs are limited due to their challenging synthetic protocols and difficulties in forming epitaxial growth between covalent and ionic bonds. Herein, we have synthesized the CsPbBr₃ perovskite NRs-platinum (Pt) nanoparticles (NPs) (CsPbBr₃/Pt) epitaxial HS using cation exchange followed by chemical reduction methods with the orthorhombic Cs₂CuBr₄ NRs. Here, the tertiary ammonium ions extensively helped to form the 1D Cs₂CuBr₄, CsPbBr₃ NRs, and CsPbBr₃/Pt HSs. For CsPbBr₃/Pt HSs an epitaxial relationship has been established in the (020) plane of orthorhombic CsPbBr₃ with the (020) plane of cubic Pt. Further, femtosecond transient absorption (TA) spectroscopy was employed to study the charge carrier dynamics of CsPbBr₃/Pt HS. Upon 420 nm photoexcitation, excitons in the conduction band of CsPbBr₃ NRs dissociate by electron transfer (with an ultrafast time of 1.1 ps) to the Pt domain. In addition, charge transfer (CT) was also demonstrated in the CsPbBr₃/Pt HS, which is ascribed to strong electron coupling and epitaxial growth between CsPbBr₃ and Pt states. This extensive understanding of the electron transfer dynamics of CsPbBr₃/Pt epitaxial HS may pave the way to designing highly efficient photovoltaic and photocatalytic applications.