Heterostructure-Controlled Charge Transfer Dynamics in CdSe/CdS Dot-in-Rods and Tetrapods.

Abstract

Heterostructured quantum dots are powerful platforms for driving photocatalytic reactions, yet the influence of morphology on charge transfer dynamics remains incompletely understood. Here, we use transient absorption spectroscopy to directly compare quasi-type-II CdSe/CdS dot-in-rods and tetrapods synthesized from a common CdSe core by examining their excited state dynamics and charge transfer behavior. We find that hole transfer from CdS to CdSe is 3-6 times slower in tetrapods than in dot-in-rods, a result we attribute to hole hopping between equivalent CdS arms, which competes with interfacial transfer. While electron transfer rates to benzoquinone are nearly identical for both heterostructures, the charge-separated state in tetrapods persists more than an order of magnitude longer, likely due to steric constraints that inhibit charge recombination. These findings demonstrate that the branched morphology of tetrapods enhances charge separation lifetime without sacrificing charge transfer kinetics, underscoring the potential of tetrapods as superior photocatalysts for light-driven chemical transformations.