Bright and Stable ZnSeTe Core/Shell Quantum Dots Enabled by Surface Passivation with Organozinc Halide Ligands

Improving the quantum yield and stability of environmentally friendly colloidal quantum dots (CQDs) is crucial for next-generation commercial optoelectronics. Recent research suggests that passivation of both cations and anions on the CQD surfaces leads to high photoluminescence quantum yields (PLQYs). Zinc carboxylate and zinc chloride can bind to both cations and anions; however, these bindings result in poor colloidal and PL stabilities of CQDs. Here, we develop bright and stable ZnSeTe/ZnSe/ZnSeS/ZnS CQDs by introducing the organozinc halide 4-methylbenzylzinc chloride (4MBZC), which is capable of dual-ion passivation. This ligand system displays a near-unity QY of 99.0% with blue emission at 436.8 nm and a narrow full width at half-maximum of 24.4 nm. Moreover, the surface-modified CQDs (4MBZC-QDs) exhibit enhanced colloidal and PL stabilities compared to zinc carboxylate and zinc chloride-coated CQDs (Zn(St)2-QDs and ZnCl2-QDs). 4MBZC-QDs exhibit no aggregation and maintain 84.8% of the initial PLQY even after storage for 1728 h, while those of Zn(St)2-QDs and ZnCl2-QDs are at 3.6 and 23.2%, respectively. The Zn–Cl parts of the organometallic passivate both the Zn and S of the ZnS shell, and the aromatic moieties of the ligand suppress particle aggregation. Our surface engineering approach guides the development of eco-friendly photoelectric devices.