Ultrafast Interfacial\nCharge Transfer in Anisotropic\nOne-Dimensional CsPbBr<sub>3</sub>/Pt Epitaxial Heterostructure

Colloidal one-dimensional (1D) perovskite nanorods (NRs)\nand metal\nepitaxial heterostructures (HSs) are the promising class of new materials\nfor efficient photovoltaic and photocatalytic applications. Besides,\nfundamental photophysical properties and its device applications of\n1D perovskite–metal HSs are limited due to their challenging\nsynthetic protocols and difficulties in forming epitaxial growth between\ncovalent and ionic bonds. Herein, we have synthesized the CsPbBr<sub>3</sub> perovskite NRs–platinum (Pt) nanoparticles (NPs) (CsPbBr<sub>3</sub>/Pt) epitaxial HS using cation exchange followed by chemical\nreduction methods with the orthorhombic Cs<sub>2</sub>CuBr<sub>4</sub> NRs. Here, the tertiary ammonium ions extensively helped to form\nthe 1D Cs<sub>2</sub>CuBr<sub>4</sub>, CsPbBr<sub>3</sub> NRs, and\nCsPbBr<sub>3</sub>/Pt HSs. For CsPbBr<sub>3</sub>/Pt HSs an epitaxial\nrelationship has been established in the (020) plane of orthorhombic\nCsPbBr<sub>3</sub> with the (020) plane of cubic Pt. Further, femtosecond\ntransient absorption (TA) spectroscopy was employed to study the charge\ncarrier dynamics of CsPbBr<sub>3</sub>/Pt HS. Upon 420 nm photoexcitation,\nexcitons in the conduction band of CsPbBr<sub>3</sub> NRs dissociate\nby electron transfer (with an ultrafast time of 1.1 ps) to the Pt\ndomain. In addition, charge transfer (CT) was also demonstrated in\nthe CsPbBr<sub>3</sub>/Pt HS, which is ascribed to strong electron\ncoupling and epitaxial growth between CsPbBr<sub>3</sub> and Pt states.\nThis extensive understanding of the electron transfer dynamics of\nCsPbBr<sub>3</sub>/Pt epitaxial HS may pave the way to designing highly\nefficient photovoltaic and photocatalytic applications.