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A polymer/small-molecule binary-blend hole transport layer for enhancing charge balance in blue perovskite light emitting diodes
Journal of Materials Chemistry A ( IF 11.9 ) Pub Date : 2022-06-08 , DOI: 10.1039/d2ta01987f
Zhongkai Yu, Woo Hyeon Jeong, Keehoon Kang, Hochan Song, Xinyu Shen, Hyungju Ahn, Seok Woo Lee, Xiangyang Fan, Ji Won Jang, Su Ryong Ha, Jeong Wan Min, Jong Hyun Park, Jongmin Han, Eui Dae Jung, Myoung Hoon Song, Dong Wook Chang, Won Bin Im, Sung Heum Park, Hyosung Choi, Bo Ram Lee

Metal halide based perovskite light-emitting diodes (PeLEDs) are promising candidates for next generation commercial display products due to their excellent high color-purity and recent dramatic improvements in their device efficiencies. However, the performance of blue PeLEDs falls far short of the requirements of commercialization, for which one of the main reasons is the wide band gap of blue-emitting perovskites, resulting in inferior hole injection and imbalanced charge transport in the emissive layer. Here, we introduce a facile method for overcoming the charge balance issue by developing a polymer/small-molecule binary-blend hole transport layer (HTL) with poly(9-vinylcarbazole) (PVK) and 2-(4-biphenyl)-5-(4-tert-butylphenyl)-1,3,4-oxadiazole (PBD). The binary-blend HTL allows a systematic modulation of the hole injection barrier that enabled balanced charge transport between electrons and holes for an effective recombination within the perovskite emissive layer. In particular, the PeLED based on our optimal blended HTL exhibits one of the highest external quantum efficiency (EQE) values of 5.30% for blue PeLEDs with an emission peak at 478 nm. Our work provides a simple and effective concept for forming an energy ladder for efficient charge transport which will contribute towards developing high performance blue PeLEDs.

中文翻译:

用于增强蓝色钙钛矿发光二极管电荷平衡的聚合物/小分子二元混合空穴传输层

基于金属卤化物的钙钛矿发光二极管 (PeLED) 因其出色的高色纯度和最近在器件效率方面的显着改进而成为下一代商业显示产品的有希望的候选者。然而,蓝色PeLED的性能远未达到商业化的要求,主要原因之一是蓝色发光钙钛矿的禁带宽度宽,导致空穴注入较差,发光层中的电荷传输不平衡。在这里,我们介绍了一种通过使用聚(9-乙烯基咔唑)(PVK)和 2-(4-联苯)-5 开发聚合物/小分子二元混合空穴传输层 (HTL) 来克服电荷平衡问题的简便方法。 -(4--丁基苯基)-1,3,4-恶二唑(PBD)。二元混合 HTL 允许对空穴注入势垒进行系统调制,从而实现电子和空穴之间的平衡电荷传输,从而在钙钛矿发射层内实现有效复合。特别是,基于我们的最佳混合 HTL 的 PeLED 对于蓝色 PeLED 表现出最高的外部量子效率 (EQE) 值之一,其发射峰在 478 nm。我们的工作为形成高效电荷传输的能量阶梯提供了一个简单而有效的概念,这将有助于开发高性能蓝色 PeLED。
更新日期:2022-06-08
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