Exciton dynamics in cation-exchanged CdSe/PbSe nanorods: The role of defects

[Display omitted] •CdSe/PbSe type II nanorod heterostructures are prepared by cation exchange.•Transient absorption study reveals significant carrier trapping at defect sites formed in the cation exchange process.•Transient absorption study reveals the reduction of defect density and increase of carrier lifetime by annealing the nanorod. Cation exchange occurs via defect initiated solid-state diffusion, a process that can lead to defect formations. The effect of such inherent defect formation on carrier dynamics of cation-exchanged heterostructures remains poorly understood. Herein, we report exciton dynamics in type II CdSe/PbSe heterostructure nanorods formed via cation exchange. The majority of electrons in CdSe domains decays in 5ps due to ultrafast carrier trapping. The defect generated by cation exchange can be healed by annealing the as-synthesized CdSe/PbSe heterostructure nanorods. This study suggests a strategy for improving properties of heteronanostructures prepared by cation exchange for applications in photovoltaics and photocatalysis.