Precursor Reactivity‐Controlled Synthesis of ZnSeTe Spherical Quantum Wells with Narrow and Symmetric Photoluminescence

Abstract Environment‐friendly ZnSeTe quantum dots (QDs) are considered as potential blue light emitters. However, due to the large reaction activity difference between Se and Te precursors, ZnSeTe QDs usually can not uniformly alloyed and generate lattice distortion, reducing the color purity or photoluminescence quantum yield (PLQY). A ZnSe/ZnSeTe/ZnSe spherical quantum well (SQW) structure with quasi type‐II energy band arrangement is designed. To promote the uniform growth and even alloying of ternary ZnSeTe, weakly active biphenyltellurium (Ph₂Te₂) is applied as a new Te source for balancing the reactivity between Te and Se. Epitaxial growth of high crystallinity ZnSeTe with greatly reduced defects is obtained. After ZnS outer layer passivation, the obtained ZnSe/ZnSeTe/ZnSe/ZnS QDs exhibit a high PLQY (≈84%) and a narrow full width at half maxima (19 nm) without asymmetric broaden at 455 nm, contributing to an ultrahigh color purity, which is among the best photoluminescence performance for blue emitting ZnSeTe based QDs. This work provides a new balance strategy of precursor reactivity for synthesizing high color purity and heavy metal free blue ZnSeTe QDs.