基于双极聚集诱导延迟荧光材料制备高效稳定厚膜非掺杂有机发光二极管

Efficient and Stable Thick-layer Non-doped Organic Light-emitting Diodes Based on Bipolar Aggregation-induced Delayed Fluorescence Materials

摘要

厚膜有机发光二极管(OLED)是由一层厚膜同时行使载流子传输与发光功能的器件, 在简化制备工艺和提升工作稳定性方面优势显著. 然而, 要获得高效的非掺杂厚膜OLED器件, 发光材料必须兼具平衡的双极载流子传输特性, 高固态发光效率和高激子利用率, 对发光材料的设计提出了更高的要求. 本研究选取2个代表性的双极聚集诱导延迟荧光(AIDF)材料应用于此类器件的制备. 基于这些材料制备的厚膜器件表现出优异的电致发光性能, 具有启亮电压低(约2.5 V), 外量子效率高(达19.8%), 以及高亮度下效率滚降非常低等优点. 此外, 厚膜器件的工作寿命比薄膜器件提升了2倍以上. 这些厚膜还可以敏化窄光谱多重共振发光材料来制备高效率、 高色纯度、 结构简化的厚膜超荧光OLED器件. 以上结果表明, 该双极AIDF材料是制备简易厚膜OLED器件的有潜力的候选材料. 本研究为开发高效稳定的OLED器件提供了一个新策略.

Abstract

Thick-layer organic light-emitting diodes（OLEDs） comprising a single thick film to simultaneously transport carriers and emit light offer significant advantages in simplifying the fabrication process and enhancing operational stability. However， achieving highly efficient thick-layer non-doped OLEDs requires emitters possessing balanced bipolar carrier transport， strong solid-state emission and high exciton utilization， which impose high requirements on designing luminescent materials. In this work， two representative bipolar aggregation-induced delayed fluorescence（AIDF） emitters are employed to fabricate such thick-layer non-doped devices. Excellent electroluminescence（EL） performances are attained with low turn-on voltages（2.5 V）， high external quantum efficiencies（19.8%）， and negligible efficiency roll-off at high luminance. Furthermore， the operational lifetime of the thick-layer device increases by more than twofold compared to that of the thin-layer devices. In addition， high- efficiency， high-color-purity simplified thick-layer hyperfluorescence OLEDs are also achieved by using their thick neat films as sensitizers for multi-resonance emitters. These results indicate that the bipolar AIDF emitters are promising candidates for constructing simple thick-layer OLEDs， which provides a feasible strategy for developing highly efficient and stable OLEDs.

关键词

聚集诱导延迟荧光 / 有机发光二极管 / 厚膜非掺器件 / 平衡双极载流子传输 / 超荧光

Key words

Aggregation-induced delayed fluorescence / Organic light-emitting diode（OLED） / Thick-layer non-doped OLED / Balanced bipolar charge transport / Hyperfluorescence