Identification of Interfacial Electronic Structure of InP/ZnSe/ZnS Quantum Dots
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Numerous studies have reported InP quantum dots (QDs) with excellent photoluminescence (PL) quantum yield (QY) over 85%. Typical InP QDs adopted type-I band gap configuration using wide band gap ZnSe and ZnS (InP/ZnSe/ZnS). Despite similar apparent PL characteristics, their exciton recombination lifetimes were largely scattered from 20 ns to 50 ns, whereas type-I CdSe QDs exhibited 20s ns. To scrutinize the exciton recombination pathways in InP/ZnSe/ZnS QDs, here, we investigated their chemical and electronic structures. We found that the In-to-Zn exchange reaction involved in the shell growth led to the reduction in band gap and retarded exciton recombination rate. X-ray diffraction and spectroscopic analysis conclude that the Zn3P2 phase at core-shell interface implant the new electronic states near the 1Sh state accepting photogenerated holes. Our findings will promote to understand the electronic structure of heterovalent III-V/II-VI interface in QDs.