Extremely long-lived charge separation and related carrier spin excitation in CsPbBr3 perovskite quantum dots with an electron acceptor benzoquinone

Abstract

The formation and evolution dynamics of charge separation (CS) in a complex of CsPbBr₃ quantum dots (QDs) and 1,4-benzoquinone (BQ) molecules are measured with a high-sensitive pump-orientation-probe technique by which spin signals of the CS state are monitored. An extraordinarily long-lasting CS is observed, with a characteristic time being up to a dozen days under ambient conditions, due to electron transferring from QDs to BQ molecules. Upon the long-lived CS, spin coherences of both electrons and holes are detected at room temperature, with a spin dephasing time of 420 and 26 ps, respectively. The long-lived CS and spin coherence have important implications for applications of perovskite nanomaterials in photocatalysis, photovoltaics, and spintronics.