有机/无机复合双层电子传输层的量子点发光二极管

采用有机/无机复合双层电子传输层(ETL)研制绿色QLEDs, 其中有机ETL采用OLED中常见的 ETL材料, 无机ETL采用ZnO纳米颗粒, 并通过调控有机ETL厚度改变电子注入, 使电子/空穴达到平衡。制备的器件结构为: ITO/PEDOT∶PSS/TFB/QDs/ZnO NPs/TPBI∶Liq/Al, 其中有机电子传输层TPBI∶Liq采用真空蒸镀沉积。与仅采用ZnO电子传输层的器件相比, 可以使器件性能得到大幅提升: 器件的最大电流效率从11.53 cd/A提升到22.77 cd/A, 同时器件的启亮电压、电致发光光谱无明显变化。判断有机ETL的主要作用是抑制了过量电子的注入和传输, 在发光亮度变化不大的情况下, 降低了器件的无效复合(例如俄歇复合)电流, 从而使电流效率明显提升。

Abstract

A unique ETL, composed of conventional organic materials used in OLED and ZnO nanoparticles(ZnO NPs) was adoped to improve the green-QLED device performance. The thickness of the organic ETL was adjusted to control the electron injection, therefore balance the electron/hole ratio. The device architecture of the green QLED fabricated in this work was ITO/PEDOT∶PSS/TFB/QDs/ZnO NPs/TPBI∶Liq/Al, in which the organic ETL was co-evaporated from TPBI and Liq. Compared with the device only having ZnO as the ETL, an additional organic ETL boosted the maximum current efficiency from 11.53 cd/A to 22.77 cd/A, without any significant impact on the turn-on voltage and the electroluminescence spectrum. We propose that the additional organic ETL has helped to suppress excess amounts of electrons being injected into the QD emissive layer, reducing the inefficient recombination (like Auger recombination) current without sacrificing much of the emission output, and eventually improved the device efficiency.

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陈亚文, 黄航, 魏雄伟, 李哲, 宋晶尧, 谢相伟, 付东, 陈旭东. 有机/无机复合双层电子传输层的量子点发光二极管[J]. 发光学报, 2018, 39(10): 1439. CHEN Ya-wen, HUANG Hang, WEI Xiong-wei, LI Zhe, SONG Jing-yao, XIE Xiang-wei, FU Dong, CHEN Xu-dong. QLEDs with Organic/Inorganic Hybrid Double Electron Transport Layers[J]. Chinese Journal of Luminescence, 2018, 39(10): 1439.

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