Molecular‐Additive‐Assisted Tellurium Homogenization in ZnSeTe Quantum Dots

Abstract

AbstractAddition of aqueous hydrohalic acids during the synthesis of colloidal quantum dots (QDs) is widely employed to achieve high‐quality QDs. However, this reliance on the use of aqueous solutions is incompatible with oxygen‐ and water‐sensitive precursors such as those used in the synthesis of Te‐alloyed ZnSe QDs. Herein, it is shown that this incompatibility leads to phase segregation into Te‐rich and Te‐poor regions, causing spectral broadening and luminescence peak shifting under high laser irradiation and applied electrical bias. Here, a synthetic strategy to produce anhydrous‐HF in situ by using benzenecarbonyl fluoride (BF) as a chemical additive is reported. Through in situ 19F NMR spectroscopy, it is found that BF reacts with surfactants in tandem, ultimately producing intermediary F···H···trioctylamine adducts. These act as a pseudo‐HF source that releases anhydrous HF. The controlled release of HF during nucleation and growth steps homogenizes Te distribution in ZnSeTe lattice, leading to spectrally stable blue‐emitting QDs under increasing laser flux from ≈3 µW to ≈12 mW and applied bias from 2.6 to 10 V. Single‐dot photoluminescence (PL) spectroscopy and analyses of the absorption, PL and transient absorption spectra together with density functional theory point to the role of anhydrous HF as a Te homogenizer.