Poly[(9,9-dioctylfluorenyl-2,7-diyl)-alt(4,4'-(N-(4-butylphenyl))] (TFB) has been widely used as a hole transport layer (HTL) material in cadmium-based quantum dots light-emitting diodes (QLEDs) due to its high hole mobility. However, as the highest occupied molecular orbital (HOMO) energy level of TFB is -5.4 eV, the hole injection from TFB to quantum dots (QDs) layer is higher than 1.5 eV. Such high oxidation potential at the QD/HTL interface may seriously degrade the device lifetime. In addition, TFB is not resistant to most solvents, which limits its application in inkjet-printed QLEDs display. In this study, blended HTL consisting of TFB and cross-linkable small molecular 4,4'-bis(3-vinyl-9H-carbazol-9-yl)1,1'-biphenyl (CBP-V) was introduced into red QLEDs, because of the deep HOMO energy level of CBP-V (-6.2eV). Compared with the TFB only devices, the external quantum efficiency (EQE) of devices with blended HTL improved from 15.9 % to 22.3 % without the increase of turn-on voltage for spin-coating fabricated device. Furthermore, the blended HTL prolonged the T90 and T70 lifetime from 5.4 h and 31.1 h to 39.4 h and 148.9 h，respectively. These enhancements in lifetime are attributed to the low hole-injection barrier at HTL/QD interface and high thermal stability of blended HTL after crosslinking. Moreover, the crosslinked blended HTL showed excellent solvent resistance after cross-linking and the EQE of the inkjet-printed red QLEDs reached 16.9 %.

中文翻译：

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在QLED中实现22.3％的EQE和7倍的使用寿命提高：通过将聚合物TFB和可交联的小分子混合用于耐溶剂的空穴传输层。

与仅使用TFB的器件相比，具有混合HTL的器件的外部量子效率（EQE）从15.9％提高到22.3％，而旋涂的制造器件的开启电压却没有增加。此外，混合的HTL分别将T90和T70的寿命从5.4 h和31.1 h延长至39.4 h和148.9 h。这些寿命的提高归因于HTL / QD界面处的低空穴注入势垒和交联后混合HTL的高热稳定性。而且，交联后的混合HTL在交联后显示出优异的耐溶剂性，并且喷墨印刷的红色QLED的EQE达到16.9％。混合的HTL将T90和T70的寿命分别从5.4 h和31.1 h延长到39.4 h和148.9 h。这些寿命的提高归因于HTL / QD界面处的低空穴注入势垒和交联后混合HTL的高热稳定性。而且，交联后的混合HTL在交联后显示出优异的耐溶剂性，并且喷墨印刷的红色QLED的EQE达到16.9％。混合的HTL将T90和T70的寿命分别从5.4 h和31.1 h延长到39.4 h和148.9 h。这些寿命的提高归因于HTL / QD界面处的低空穴注入势垒和交联后混合HTL的高热稳定性。而且，交联后的混合HTL在交联后显示出优异的耐溶剂性，并且喷墨印刷的红色QLED的EQE达到16.9％。