We report full-color quantum-dot-based light-emitting diodes (QLEDs) with high efficiency and long-lifetime by employing high quantum-yield core/shell QDs with thick shells. The increased shell thickness improves the confinement of excitons in the QD cores, and helps to suppress Auger recombination and Förster resonant energy transfer among QDs. Along with optimizing the QD emitting layer thickness and hole transport materials, we achieved significant improvements in device performance as a result of increasing the QD shell thickness to above 5 nm. By using poly[9,9-dioctylfluorene-co-N-[4-(3-methylpropyl)]-diphenylamine] (TFB) as a HTL with a 38 nm thick QD layer, these QLEDs show maximum current efficiencies of 18.9 cd A⁻¹, 53.4 cd A⁻¹, and 2.94 cd A⁻¹, and peak external quantum efficiencies (EQEs) of 10.2%, 15.4%, and 15.6% for red, green, and blue QLEDs, respectively, all of which are well maintained over a wide range of luminances from 10² to 10⁴ cd m⁻². To the best of our knowledge, this is the first report of blue QLEDs with η_EQE > 15%. Most importantly, these devices also possess long lifetimes with T₇₀ (the time at which the brightness is reduced to 70% of its initial value) of 117 h (red, with an initial luminance of 8000 cd m⁻²), 84 h (green, 6000 cd m⁻²) and 47 h (blue, 420 cd m⁻²). With further optimization of QD processing and device structures, these LEDs based on thick-shell QDs show great promise for use in next-generation full-color displays and lighting devices.

中文翻译：

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利用高发光量子效率的高寿命全色发光二极管产生厚壳量子点

我们通过采用具有厚壳的高量子产率核/壳QD来报告具有高效率和长寿命的基于全色量子点的发光二极管（QLED）。增加的壳厚度改善了激子在QD核中的约束，并有助于抑制Auger重组和QD之间的Förster共振能量转移。随着QD发射层厚度和空穴传输材料的优化，由于将QD外壳厚度增加到5 nm以上，我们在器件性能方面取得了显着改善。通过使用具有38 nm厚QD层的HTL使用聚[9,9-二辛基芴-co -N- [4-（3-甲基丙基）]-二苯胺]（TFB），这些QLED的最大电流效率为18.9 cd A ^-1，53.4光盘^-1，和2.94光盘^-1，并且红色，绿色和蓝色QLED的峰值外部量子效率（EQE）分别为10.2％，15.4％和15.6％，所有这些在10 ²至10 ⁴的宽亮度范围内都得到了很好的维持cd m ^-2。据我们所知，这是蓝色QLEDs的第一份报告η _EQE > 15％。最重要的是，这些设备还具有117 h（红色，初始亮度为8000 cd m ^-2）的T ₇₀（亮度降低到其初始值的70％的时间）的长寿命。绿色，6000 cd m ^-2）和47 h（蓝色，420 cd m ^-2）。通过进一步优化QD处理和器件结构，这些基于厚壳QD的LED有望在下一代全彩显示器和照明设备中使用。