Ultrafast Interfacial Charge Transfer in Anisotropic One-Dimensional CsPbBr/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 CsPbBr perovskite NRs-platinum (Pt) nanoparticles (NPs) (CsPbBr/Pt) epitaxial HS using cation exchange followed by chemical reduction methods with the orthorhombic CsCuBr NRs. Here, the tertiary ammonium ions extensively helped to form the 1D CsCuBr, CsPbBr NRs, and CsPbBr/Pt HSs. For CsPbBr/Pt HSs an epitaxial relationship has been established in the (020) plane of orthorhombic CsPbBr with the (020) plane of cubic Pt. Further, femtosecond transient absorption (TA) spectroscopy was employed to study the charge carrier dynamics of CsPbBr/Pt HS. Upon 420 nm photoexcitation, excitons in the conduction band of CsPbBr 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 CsPbBr/Pt HS, which is ascribed to strong electron coupling and epitaxial growth between CsPbBr and Pt states. This extensive understanding of the electron transfer dynamics of CsPbBr/Pt epitaxial HS may pave the way to designing highly efficient photovoltaic and photocatalytic applications.