Large Scale Synthesis of Red-Emitting Quantum Dots for Efficient and Stable Light-Emitting Diodes

It is known that large-scale synthesis of emitters affords colloidal quantum dot (CQD) materials with a great opportunity toward the mass production of quantum dot light-emitting diodes (QLEDs) based commercial electronic products. Herein, an unprecedented example of scalable CQD (> 0.5 kilogram) is achieved by using a core/shell structure of CdZnSe/ZnSeS/CdZnS, in which CdZnSe, ZnSeS, and CdZnS alloys are used as the inner core, transition layer and outermost shell, respectively. It exhibits a high fluorescence quantum yield (>90%), a robust excited state, and a fast radiative transition rate. The investigation of morphology and surface state reveals the possible reasons for such excellent optical properties, which include uniform size distribution, no undesired byproducts, and high defect tolerance. The QLEDs exhibit a peak external quantum efficiency of over 21%, a high luminance of over 9.5×10⁴ cd m^-2, and a long lifetime of over 1.0×10⁶ h, corresponding to the state-of-the-art performance among the QLEDs based on the large-scale synthesis of CQDs. Therefore, it is believed that an efficient and reliable strategy is provided toward the large-scale synthesis of CQDs, which can be used as emitters in the QLEDs-based commercial electronic devices and make the mass production of these products a reality.