Solution-Processed organic light emitting diodes (OLEDs) have been intensively studied due to the simple preparation process. However, the devices made of small molecular luminescent materials always suffer from the reduce of the carrier transport capacity by the influence of molecular agglomeration. In this work, small-molecules material 4,4',4''-tris(N-carbazolyl)-triphenylamine (TCTA) is successfully introduced into the molecular aggregation site formed by traditional host material 1,3-Di-9-carbazolylbenzene (mCP), improving the charge mobility of the emitting layer. Doped mCP film has more compact molecular packing, which makes it has better charge transfer performance as a solid solvent of 2,3,4,6-tetrakis(9H-carbazole-9-yl)−5-fluorobenzonitrile (4CzFCN). Besides, 3 wt% of TCTA is beneficial to optimized electrochemical doping, lowering the surface potential of emitting layer and promoting holes injection. Doped host-guest system device exhibits a maximum current efficiency (CE_max = 29.6 cd/A) which has improved about 60% compared to the device with host of pure mCP (CE_max = 18.5 cd/A). The findings may provide a strategy for the future research on the film structure of solution-processed small molecule OLEDs.

由于制备过程简单，溶液处理的有机发光二极管 (OLED) 已被深入研究。然而，由小分子发光材料制成的器件总是受到分子团聚影响载流子传输能力的降低。在这项工作中，小分子材料4,4',4''-三(N-咔唑基)-三苯胺(TCTA)被成功引入到传统主体材料1,3-二-9-咔唑基苯形成的分子聚集位点(mCP)，提高发光层的电荷迁移率。掺杂的 mCP 膜具有更紧密的分子堆积，这使其作为 2,3,4,6-四(9H-咔唑-9-基)-5-氟苄腈 (4CzFCN) 的固体溶剂具有更好的电荷转移性能。此外，3 wt% 的 TCTA 有利于优化电化学掺杂，降低发光层的表面电位，促进空穴注入。掺杂的主客体系统设备表现出最大的电流效率（CE_max = 29.6 cd/A)，与带有纯 mCP 主机的设备相比提高了约 60%（CE _max = 18.5 cd/A）。该发现可能为未来溶液加工小分子OLED薄膜结构的研究提供策略。