Minimizing Defects in Blue-Emitting ZnSeTe Quantum Dots Using ZnF₂ Throughout Core and Shell Growth

ZnSeTe quantum dots (QDs) are attractive candidates for next-generation blue-light display applications. However, their optical performance is often compromised by surface and structural defects that introduce nonradiative recombination pathways. Although various synthetic strategies-such as post-synthetic surface passivation and hydrofluoric acid (HF) treatment-have been explored to mitigate these defects, they typically involve complex protocols or hazardous reagent handling. Here, we present a facile and scalable synthetic strategy for producing high-quality blue-emitting ZnSeTe QDs by employing ZnF₂ as a multifunctional precursor throughout both core and shell growth. ZnF₂ enhances optical properties (i) by suppressing crystal and surface defects through sustained in situ HF generation, and (ii) by functioning simultaneously as Z-type and X-type surface ligands for effective surface passivation. This approach yields ZnSeTe QDs with a photoluminescence quantum yield (PLQY) approaching unity (0.98), accomplished by suppressing both surface and lattice defects to minimize nonradiative recombination pathways. Our facile methodology provides a safe and effective route toward cadmium-free, high-performance blue-emitting QDs for optoelectronic applications.