Near-Zero Segregation on Strongly Exciton Confined Mixed Halide Perovskites Quantum Dots via Octahedron Alloying Reconstruction Engineering

The state-of-the-art mixed-halide perovskite (MHP) quantum dots (QDs) open up promising applications in photovoltaic and optoelectronic communities, yet are limited by huge halide segregation. In contrast to the previous A-site alloy method, customizing other octahedral units for replacing the fundamental optoelectronic unit of [PbX 6 ] 4− (X = Cl, Br, or I), the so-called B-site alloying strategy, is expected to inhibit halide segregation fully. Here, a halide octahedron alloying reconstruction engineering is reported to fabricate MHP QDs with near-zero halide segregation due to their strongly confined excitons. This unprecedented regime is obtained at a water–oil interfacial reaction system using amino-silane ion exchange accelerator and transition metal hydroxy-halides salts, introducing abundant [MX 6 ] 4− (M = Zn, Ni, Co, Mn, and Cu) octahedron block and finally fabricating transition metal-alloyed MAPbX 3 QDs. Photo-induced excitons in strongly dielectric-confined Zn-alloyed perovskite QDs are hardly thermally dissociated and transferred, as featured by ultra-high exciton binding energy (E b ), fast fluorescence lifetimes (τ avg ), and near 100% photoluminescence quantum yield (PLQY). The fabricated mixed-halide MAPb 1-x Zn x X 3 QDs with reduced Pb content over 40% exhibit near-zero halide segregation, marking the emergence of a practical solution to the detrimental segregation problem, which paves the wave for emerging solar cells and lighting display applications.