Xie Liming, Shi Jinrong, Wang Ting, Li Qing, Yi Yuan-Qiu-Qiang, Zhang Qing, Liu Yang, Su Wenming, Bae Byung Seong, Onwudiwe Damian Chinedu, Lei Wei, Cui Zheng, Luscombe Christine K
Joint International Research Laboratory of Information Display and Visualization, School of Electronic Science and Engineering, Southeast University, Nanjing 210096, China.
Printable Electronics Research Center, Nano Devices and Materials Division, Suzhou Institute of Nano-Tech and Nano-Bionics, Chinese Academy of Sciences, Suzhou, Jiangsu 215123, China.
ACS Appl Mater Interfaces. 2024 Sep 18;16(37):49563-49573. doi: 10.1021/acsami.4c08943. Epub 2024 Sep 4.
In this work, an efficient and robust hole transport layer (HTL) based on blended poly((9,9-dioctylfluorenyl-2,7-diyl)--(9-(2-ethylhexyl)-carbazole-3,6-diyl)) (PF8Cz) and crosslinkable 3,3'-(9,9-dimethyl-9-fluorene-2,7-diyl)bis(9-(4-vinylphenyl)-9-carbazole) (FLCZ-V) is introduced for high-performance and stable blue quantum dot-based light-emitting diodes (QLEDs), wherein FLCZ-V can in situ-crosslink to a continuous network polymer after thermal treatment and the linear polymer PF8CZ becomes intertwined and imprisoned. As a result, the blended HTL shows a high hole mobility (1.27 × 10 cm V s) and gradient HOMO levels (-5.4 eV of PF8CZ and -5.7 eV of FLCZ-V) that can facilitate hole injecting so as to ameliorate the charge balance and, at the same time, achieve better electron-blocking capability that can effectively attenuate HTL decomposition. Meanwhile, the crosslinked blended HTL showed excellent solvent resistance and a high surface energy of 40.34 mN/m, which is favorable to enhance wettability for the deposition of a follow-up layer and attain better interfacial contact. Based on the blended HTL, blue QLEDs were fabricated by both spin-coating and inkjet printing. For the spin-coated blue QLED, a remarkable enhancement of external quantum efficiency (EQE) of 15.5% was achieved. Also, the EQE of the inkjet-printed blue QLED reached 9.2%, which is thus far the best result for the inkjet-printed blue QLED.
在本工作中，引入了一种基于聚（（9,9 - 二辛基芴 - 2,7 - 二基） - （9 - （2 - 乙基己基） - 咔唑 - 3,6 - 二基））（PF8Cz）和可交联的3,3' - （9,9 - 二甲基 - 9 - 芴 - 2,7 - 二基）双（9 - （4 - 乙烯基苯基） - 9 - 咔唑）（FLCZ - V）的高效且稳健的空穴传输层，用于高性能和稳定的蓝色量子点发光二极管（QLED），其中FLCZ - V在热处理后可原位交联成连续的网络聚合物，而线性聚合物PF8CZ则相互缠结并被禁锢。结果，混合空穴传输层显示出高空穴迁移率（1.27×10 cm V s）和梯度HOMO能级（PF8CZ为 - 5.4 eV，FLCZ - V为 - 5.7 eV），这有助于空穴注入，从而改善电荷平衡，同时实现更好的电子阻挡能力，可有效减弱空穴传输层的分解。同时，交联的混合空穴传输层表现出优异的耐溶剂性和40.34 mN/m的高表面能，这有利于提高后续层沉积的润湿性并实现更好的界面接触。基于该混合空穴传输层，通过旋涂和喷墨印刷制备了蓝色QLED。对于旋涂的蓝色QLED，实现了15.5%的外量子效率（EQE）显著提高。此外，喷墨印刷的蓝色QLED的EQE达到9.2%，这是迄今为止喷墨印刷蓝色QLED的最佳结果。
