Shen Xinyu, Wu Hua, Zhang Xiaoyu, Xu Meili, Hu Junhua, Zhu Jinyang, Dong Bin, Yu William W, Bai Xue
State Key Laboratory of Integrated Optoelectronics and College of Electronic Science and Engineering, Jilin University, Changchun 130012, China.
State Centre for International Cooperation on Designer Low-carbon & Environmental Materials, School of Materials Science and Engineering, Zhengzhou University, Zhengzhou 450001, China.
J Phys Chem Lett. 2021 Jan 14;12(1):94-100. doi: 10.1021/acs.jpclett.0c03047. Epub 2020 Dec 11.
Light-emitting devices (LEDs) with inorganic perovskite nanocrystals (PNCs) fabricated through the all-solution process have tremendous potential for new-generation illumination and displays on account of their large area and cost-effective manufacturing. However, the development of efficient solution-processed PNC LEDs remains challenge, which mainly results from the fact that only a few types of charge transport layers can be employed for the subsequent deposition steps, thus leading to injection barriers and charge injection imbalance inside these LEDs. Herein 4,4'-bis(carbazole-9-yl) biphenyl (CBP) is introduced as a dopant into the poly(9,9-dioctylfluorene---(4-(3-methylpropyl)) diphenylamine) (TFB) hole transport layer (HTL), which efficiently modulates the mobility of charge carrier as well as the energy level of the HTL, resulting in the barrier-free injection of the charge carrier in the as-fabricated solution-processed PNC LEDs. Consequently, the luminance of red LEDs (688 nm) reaches 2990 cd m, and the external quantum efficiency achieves 8.1%, which is the optimal performance for solution-processed PNC LEDs to date. Additionally, the turn-on voltage and roll-off have also been improved by the more balanced charge injection.
通过全溶液法制备的含有无机钙钛矿纳米晶体（PNCs）的发光器件（LED），因其大面积和具有成本效益的制造工艺，在新一代照明和显示领域具有巨大潜力。然而，高效的溶液法制备的PNC LED的发展仍然面临挑战，这主要是由于在后续沉积步骤中只能使用少数几种类型的电荷传输层，从而导致这些LED内部存在注入势垒和电荷注入不平衡。在此，将4,4'-双（咔唑-9-基）联苯（CBP）作为掺杂剂引入聚（9,9-二辛基芴-（4-（3-甲基丙基））二苯胺）（TFB）空穴传输层（HTL）中，这有效地调节了电荷载流子的迁移率以及HTL的能级，从而在制备的溶液法PNC LED中实现了电荷载流子的无势垒注入。因此，红色LED（688 nm）的亮度达到2990 cd m，外部量子效率达到8.1%，这是迄今为止溶液法PNC LED的最佳性能。此外，通过更平衡的电荷注入，开启电压和滚降也得到了改善。
