Bao Zhen, Jiang Zhen-Feng, Su Qiang, Chiu Hsin-Di, Yang Heesun, Chen Shuming, Chung Ren-Jei, Liu Ru-Shi
Department of Chemistry, National Taiwan University, Taipei 106, Taiwan.
Department of Chemical Engineering and Biotechnology, National Taipei University of Technology, Taipei 106, Taiwan.
Nanoscale. 2020 Jun 4;12(21):11556-11561. doi: 10.1039/d0nr01019g.
Cadmium-free quantum dots (QDs) are attracting considerable research attention because of their low toxicity. However, the bandgap of most cadmium-free QDs avoids the pure-blue region, which leads to difficulty in realizing pure-blue quantum-dot light-emitting diodes (QLEDs). In this work, we successfully tuned the emission wavelength of ZnSe/ZnS quantum dots from the violet region (∼420 nm) to the pure-blue region (450-460 nm) by doping Te into the ZnSe core. The ZnSe:0.03Te/ZnSeS/ZnS QD sample with emission at 450 nm and a quantum yield of 30% was the most balanced formula. To overcome the energy gap between the hole-transfer layer and QD layers, a specific hole-transfer layer was developed for normal-structure QLEDs. A QLED with such a structure with ZnSe:0.03Te/ZnSeS/ZnS QDs achieved the pure-blue light emission at 455 nm, a low turn-on voltage of 4.4 V, and an external quantum efficiency of 0.33%. Overall, our cadmium-free QLED achieved pure-blue emission, revealing the potential of ZnSe-based pure-blue QLEDs for future displays.
无镉量子点（QDs）因其低毒性而备受研究关注。然而，大多数无镉量子点的带隙避开了纯蓝光区域，这导致实现纯蓝光量子点发光二极管（QLEDs）存在困难。在这项工作中，我们通过向ZnSe核中掺杂Te，成功地将ZnSe/ZnS量子点的发射波长从紫光区域（约420 nm）调至纯蓝光区域（450 - 460 nm）。发射波长为450 nm且量子产率为30%的ZnSe:0.03Te/ZnSeS/ZnS量子点样品是最平衡的配方。为了克服空穴传输层与量子点层之间的能隙，我们为常规结构的QLEDs开发了一种特定的空穴传输层。具有这种结构且采用ZnSe:0.03Te/ZnSeS/ZnS量子点的QLED实现了455 nm的纯蓝光发射、4.4 V 的低开启电压以及0.33%的外量子效率。总体而言，我们的无镉QLED实现了纯蓝光发射，揭示了基于ZnSe的纯蓝光QLED在未来显示中的潜力。
