Ultrastable and High-Efficiency Deep Red QLEDs through Giant Continuously Graded Colloidal Quantum Dots with Shell Engineering
Xiaonan Liu, Lei Wang, Yan Gao, Yicheng Zeng, Fangze Liu, Huaibin Shen, Liberato Manna, Hongbo Li
Abstract
Quantum dot (QD) based light-emitting diodes (QLEDs) hold great promise for next-generation lighting and displays. In order to reach a wide color gamut, deep red QLEDs emitting at wavelengths beyond 630 nm are highly desirable but have rarely been reported. Here, we synthesized deep red emitting ZnCdSe/ZnSeS QDs (diameter ∼16 nm) with a continuous gradient bialloyed core–shell structure. These QDs exhibit high quantum yield, excellent stability, and a reduced hole injection barrier. The QLEDs based on ZnCdSe/ZnSeS QDs have an external quantum efficiency above 20% in the luminance range of 200–90000 cd m –2 and a record T 95 operation lifetime (time for the luminance to decrease to 95% of its initial value) of more than 20000 h at a luminance of 1000 cd m –2 . Furthermore, the ZnCdSe/ZnSeS QLEDs have outstanding shelf stability (>100 days) and cycle stability (>10 cycles). The reported QLEDs with excellent stability and durability can accelerate the pace of QLED applications.