Nanoparticle Packing-Dependent Charge Transfer Dynamics in Colloidal Binary Superparticles

A key trend in nanoparticle self-assembly as "artificial atoms" is learning from molecular systems, yet progress lags behind molecular systems because current research primarily focuses on geometric structural mimicry while ignoring the electronic communication across arrangements intrinsic to molecules. Here, inspired by the characteristic topologies of molecular compounds, we introduce "packing-structure engineering" via a ligand solubility-matched microemulsion-confined co-assembly strategy to fabricate three typical mesoscopic packing-topology structural systems from Au nanoparticles and CdSe/CdS nanorods: metal-isolated-by-semiconductor-type, metal-interlaced-with-semiconductor-type, and semiconductor-isolated-by-metal-type. We demonstrate that packing topology acts as a fundamental independent order parameter─analogous to molecular connectivity topologies─fundamentally regulating intrinsic electron dynamics. Specifically, the metal-isolated-by-semiconductor configuration enables a transition from picosecond incoherent hot-electron transfer to instantaneous coherent plasmon-induced interfacial charge-transfer transition, comparable to contacting heterostructures. This behavior may arise from unique collective coupling modes and interparticle field enhancements. This offers a pathway for minimizing thermalization losses in the plasmonic donor. Extendable to diverse systems, it can unlock emergent optoelectronic properties and high-performance materials for applications in solar cells, photodetectors, photocatalysis, and sensing.