Thick-shell CdZnSe/ZnSe/ZnS quantum dots for bright white light-emitting diodes

Abstract Quantum dots (QDs) have become promising light sources for next-generation lightings and displays. Realizing their applications in optoelectronic devices requires that QDs should retain their superior optical performances in condense QD films. However, most QD systems suffer intense photoluminescence (PL) quenching after film formation. Here, we report device-grade thick-shell CdZnSe/ZnSe/ZnS QDs with near-unity PL quantum yield (QY) in QD solution and 82% PL QY in QD film. We demonstrate that the thick shell functions well in restraining undesired inter-dot energy transfer by separating the emitting cores in condense QD film, and therefore preserving their superior emission properties. White light-emitting diodes (WLEDs) integrated with 5 different CdZnSe/ZnSe/ZnS QDs cover the visible spectrum, delivering a color rendering index (CRI) Ra as high as 91.4, a luminous efficiency (LE) of 68.5 lm/W and a warm bright sun light with correlated color temperature (CCT) of 4138 K. In particular, the champion CdZnSe/ZnSe/ZnS based WLED exhibits a special color index R9 as high as 93.1.