Ultralong Lifetime of Plasmon‐Excited Electrons Realized in Nonepitaxial/Epitaxial Au@CdS/CsPbBr₃ Triple‐Heteronanocrystals

Abstract Combination of the strong light‐absorbing power of plasmonic metals with the superior charge carrier dynamics of halide perovskites is appealing for bio‐inspired solar‐energy conversion due to the potential to acquire long‐lived plasmon‐induced hot electrons. However, the direct coupling of these two materials, with Au/CsPbBr₃ heteronanocrystals (HNCs) as a prototype, results in severe suppression of plasmon resonances. The present work shows that interfacial engineering is a key knob for overcoming this impediment, based on the creation of a CdS mediate layer between Au and CsPbBr₃ forming atomically organized Au‐CdS and CdS‐CsPbBr₃ interfaces by nonepitaxial/epitaxial combined strategy. Transient spectroscopy studies demonstrate that the resulting Au@CdS/CsPbBr₃ HNCs generate remarkably long‐lived plasmon‐induced charge carriers with lifetime up to nanosecond timescale, which is several orders of magnitude longer than those reported for colloidal plasmonic metal‐semiconductor systems. Such long‐lived carriers extracted from plasmonic antennas enable to drive CO₂ photoreduction with efficiency outperforming previously reported CsPbBr₃‐based photocatalysts. The findings disclose a new paradigm for achieving much elongated time windows to harness the substantial energy of transient plasmons through realization of synergistic coupling of plasmonic metals and halide perovskites.