单层热激活延迟荧光有机发光器件及其激子分布特性

Single-layer Thermally Activated Delayed Fluorescent Organic Light-emitting Devices and Exciton Distribution Profiles

单层结构对简化有机电致发光器件(OLED)的制备工艺及降低其制造成本具有重要意义。本文采用非掺杂热激活延迟荧光(TADF)发光层,结合C_(60)(2 nm)/MoO_(3)(3 nm)/C_(60)(2 nm)修饰的ITO阳极及4,7-二苯基-1,10-菲啰啉(Bphen,3 nm)修饰的Ag阴极,制备了单层TADF器件(TADF-OLED)。该单层TADF-OLED具有良好的空穴和电子注入能力,开启电压为3 V,最大电流、功率及外量子效率分别可达到37.7 cd/A、47.4 lm/W和13.24%。然后,我们利用“探针法”研究了该单层TADF-OLED的激子分布情况,发现大部分激子在发光层靠近阳极侧形成。最后,我们利用经典电磁学理论对器件的光取出效率进行模拟分析,证实了这种激子分布特性有助于实现较高的光取出效率,进而改善器件的外量子效率。

Developing single-layer structure is important to simplify fabrication processes and reduce manufacture costs of organic light-emitting devices(OLEDs).In this work,we develop an efficient single-layer thermal activation delayed fluorescence(TADF)OLED by combining a non-doped TADF emitting layer,a C_(60)(2 nm)/MoO_(3)(3 nm)/C_(60)(2 nm)modified ITO anode and a 4,7-Diphenyl-1,10-phenanthroline(Bphen,3 nm)modified silver cathode.The single-layer TADF-OLED can achieve efficient hole and electron injection ability such that it has a low turn-on voltage of 3 V,a maximum current efficiency of 37.7 cd/A,a maximum power efficiency of 47.4 lm/W,and an external quantum efficiency of 13.24%.And then,we investigate the exciton distribution profile of the single-layer TADF-OLED by using a“probe”method.It is found that most excitons are formed at the emitting layer close to the anode.Finally,with the classical theory of electromagnetism,we simulate and analyze the outcoupling efficiency,and prove that this exciton distribution profile is beneficial to achieve higher outcoupling efficiency,and thus the external quantum efficiency of single-layer OLEDs.