Heterostructural CsPbX-PbS (X = Cl, Br, I) Quantum Dots with Tunable Vis-NIR Dual Emission.

Perovskite and chalcogenide quantum dots (QDs) are important nano semiconductors. It has been a challenge to synthesize heterostructural QDs combining perovskite and chalcogenide with tailorable photoelectronic properties. In this report, heterostructural CsPbX-PbS (X = Cl, Br, I) QDs were successfully synthesized via a room temperature in situ transformation route. The CsPbX-PbS QDs show a tunable dual emission feature with the visible and near-infrared (NIR) photoluminescence (PL) corresponding to CsPbX and PbS, respectively. Typically, the formation and evolution of the heterostructural CsPbBr-PbS QDs with reaction time was investigated. Femtosecond transient absorption spectroscopy (TAS) was applied to illuminate the exciton dynamics in CsPbBr-PbS QDs. The mild synthetic method and TAS proved perovskite to PbS energy transfer may pave the way toward highly efficient QD photovoltaic and optoelectronic devices.