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Promoted Hole Transport Capability by Improving Lateral Current Spreading for High‐Efficiency Quantum Dot Light‐Emitting Diodes
Advanced Science ( IF 14.3 ) Pub Date : 2020-11-01 , DOI: 10.1002/advs.202001760
Qianqian Wu 1 , Fan Cao 1 , Haoran Wang 1 , Jianquan Kou 2 , Zi-Hui Zhang 2 , Xuyong Yang 1
Affiliation  

Carrier imbalance resulting from stronger electron injection from ZnO into quantum‐dot (QD) emissive layer than hole injection is one critical issue that constrains the performance of QDs‐based light‐emitting diodes (QLEDs). This study reports highly efficient inverted QLEDs enabled by periodic insertion of MoO3 into (4,4′‐bis(N‐carbazolyl)‐1,1′‐biphenyl) (CBP) hole transport layer (HTL). The periodic ultrathin MoO3/CBP‐stacked HTL results in improved lateral current spreading for the QLEDs, which significantly relieves the crowding of holes and thus enhances hole transport capability across the CBP in QLEDs. Comprehensive analysis on the photoelectric properties of devices shows that the optimal thickness for MoO3 interlayer inserted in CBP is only ≈1 nm. The resulting devices with periodic two insertion layers of MoO3 into CBP exhibit better performance compared with the CBP‐only ones, such that the peak current efficiency is 88.7 cd A−1 corresponding to the external quantum efficiency of 20.6%. Furthermore, the resulting QLEDs show an operational lifetime almost 2.5 times longer compared to CBP‐only devices.

中文翻译:

通过改善高效量子点发光二极管的横向电流扩展来提高空穴传输能力

ZnO 向量子点 (QD) 发射层的电子注入比空穴注入更强,导致载流子不平衡,这是限制 QD 发光二极管 (QLED) 性能的关键问题之一。这项研究报道了通过定期将 MoO 3插入到 (4,4'-双( N-咔唑基)-1,1'-联苯) (CBP) 空穴传输层 (HTL) 中来实现高效倒置 QLED 。周期性超薄MoO 3 /CBP堆叠HTL改善了QLED的横向电流扩散,从而显着缓解了空穴的拥挤,从而增强了QLED中跨CBP的空穴传输能力。综合器件光电性能分析表明,CBP中插入MoO 3中间层的最佳厚度仅为约1 nm。与仅 CBP的器件相比,所得到的具有周期性两个 MoO 3插入层到 CBP 的器件表现出更好的性能,使得峰值电流效率为 88.7 cd A -1,对应于 20.6% 的外部量子效率。此外,与仅使用 CBP 的设备相比,由此产生的 QLED 的使用寿命几乎延长了 2.5 倍。
更新日期:2020-12-03
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