Achieving near-unity quantum yield in blue ZnSeTe quantum dots through NH4F molecular-assisted synthesis for highly efficient light-emitting diodes

ZnSeTe quantum dots (QDs) show promise in advancing high-performance pure blue quantum dot light-emitting diodes (QLEDs) for high-definition displays, owing to their exceptional luminescent properties and environmental characteristics. However, the current most efficient synthesis method involves a challenging and hazardous step: injecting water-based hydrofluoric acid treatment under high-temperature conditions. Herein, a novel approach utilizing inorganic fluoride NH4F as a molecular additive is introduced to simplify the synthesis of highly efficient ZnSeTe/ZnSe/ZnS blue QDs. The resulting QDs exhibit tunable photoluminescence (PL) wavelengths in the pure blue region with near-unit PL quantum yield (QY). Notably, the use of NH4F passivates the ZnSeTe cores, enhancing stability and facilitating high-quality coating of the subsequent shell layer, ultimately reducing nonradiative recombination rates and improving PL QY. To evaluate the practical application of these blue ZnSeTe/ZnSe/ZnS QDs, we utilized them as an emitting layer to fabricate QLEDs with two typical structures. The results demonstrated that the external quantum efficiency of the standard QLED and inverted QLED can reach 17.2% and 16.3%, respectively, showing comparable performance to QLEDs with QDs prepared through classical HF addition synthesis steps. This environmentally friendly synthesis strategy for pure blue ZnSeTe QDs with high PL QY through NH4F assistance is expected to offer insights for synthesizing other environmentally friendly QDs, thus facilitating the development of eco-friendly QLEDs.