Highly Efficient Deep Blue Cd-Free Quantum Dot Light-Emitting Diodes by a p-Type Doped Emissive Layer.,Small

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Highly Efficient Deep Blue Cd-Free Quantum Dot Light-Emitting Diodes by a p-Type Doped Emissive Layer.
Small ( IF 13.0 ) Pub Date : 2020-09-15 , DOI: 10.1002/smll.202002109
Hyunjin Cho ₁ , Sunjoong Park ₁ , Hongjoo Shin ₁ , Moohyun Kim ₁ , Hanhwi Jang ₁ , Jaehyun Park ₂ , Joong Hwan Yang ₂ , Chang Wook Han ₂ , Ji Ho Baek ₂ , Yeon Sik Jung ₁ , Duk Young Jeon ₁

Affiliation

Environmentally friendly ZnSe/ZnS core/shell quantum dots (QDs) as an alternative blue emission material to Cd‐based QDs have shown great potential for use in next‐generation displays. However, it remains still challenging to realize a high‐efficiency quantum dot light‐emitting diode (QLED) based on ZnSe/ZnS QDs due to their insufficient electrical characteristics, such as excessively high electron mobility (compared to the hole mobility) and the deep‐lying valence band. In this work, the effects of QDs doped with hole transport materials (hybrid QDs) on the electrical characteristics of a QLED are investigated. These hybrid QDs show a p‐type doping effect, which leads to a change in the density of the carriers. Specifically, the hybrid QDs can balance electrons and holes by suppressing the overflow of electrons and improving injection of holes, respectively. These electrical characteristics help to improve device performance. In detail, an external quantum efficiency (EQE) of 6.88% is achieved with the hybrid QDs. This is increased by 180% compared to a device with pure ZnSe/ZnS QDs (EQE of 2.46%). This record is the highest among deep‐blue Cd‐free QLED devices. These findings provide the importance of p‐type doping effect in QD layers and guidance for the study of the electrical properties of QDs.

中文翻译：

通过p型掺杂发光层实现的高效深蓝色无Cd量子点发光二极管。

环保的ZnSe / ZnS核/壳量子点（QD）作为基于Cd的QD的蓝色发射材料的替代品，已显示出在下一代显示器中的巨大潜力。但是，由于基于ZnSe / ZnS QD的高效量子点发光二极管（QLED）的电学特性不足，例如电子迁移率过高（与空穴迁移率相比）过高和过深，因此仍然面临挑战。价带。在这项工作中，研究了掺杂有空穴传输材料的QD（混合QD）对QLED电气特性的影响。这些混合量子点显示出ap型掺杂效应，从而导致载流子密度发生变化。具体而言，混合量子点可以通过抑制电子的溢出并改善空穴的注入来平衡电子和空穴，分别。这些电气特性有助于改善设备性能。详细地，使用混合QD可以实现6.88％的外部量子效率（EQE）。与具有纯ZnSe / ZnS QD的器件（EQE为2.46％）相比，它增加了180％。该记录是深蓝色无镉QLED器件中最高的。这些发现为QD层中p型掺杂效应的重要性提供了指导，并为研究QD的电学性质提供了指导。

更新日期：2020-10-08

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