Solution-processable hole-transporting materials (HTMs) are key functional materials for high-throughput and inexpensive fabrication of high-efficiency organic light-emitting diodes (OLEDs). Herein, we have successfully synthesized a novel series of phenothiazine and phenoxazine substituted fluorene core-based HTMs, i.e. 10-hexyl-3-[2,7-di(naphthalen-1-yl)-fluoren-9-ylmethylene]phenoxazine DNFPhe, 10-hexyl-3-[2,7-di(4-(diphenylamino)-phenyl)fluoren-9-ylmethylene]phenoxazine DDPFPhe, 10-hexyl-3-[2,7-di(4-fluorophenyl)-fluoren-9-ylmethylene]phenoxazine DFPFPhe, 10-hexyl-3-(2,7-diphenylfluoren-9-ylmethylene)phenoxazine DPFPhe, 10-hexyl-3-[2,7-di(4-(diphenylamino)phenyl)fluoren-9-ylmethylene]phenothiazine DDPPFPh, and 10-hexyl-3-[2,7-di(naphthalen-1-yl)fluoren-9-ylmethylene]phenothiazine DNFPh, and incorporated them in solution-processed phosphorescent and thermally activated delayed fluorescence (TADF) OLEDs. The synthesized HTMs exhibit superior solubility in organic solvents and display nanotextured surface morphologies. These HTMs possess high hole-mobilities as compared to a conventional HTM, N,N′-bis(naphthalen-1-yl)-N,N′-bis(phenyl)-benzidine (NPB). By incorporating a phosphorescent bis(4-phenylthieno[3,2-c]pyridinato-N,C2′) (acetylacetonate) iridium(III) (PO-01) yellow emitter, we demonstrate an improvement in maximum power efficacy (PE_max) from 41.6 to 45.4 lm W⁻¹, current efficacy from 39.8 to 50.6 cd A⁻¹, external-quantum efficiency (EQE_max) from 12.9 to 19.6%, maximum brightness (L_max) from 15 200 to 19 400 cd m⁻², and a lifetime (LT₅₀) from 151 to 465 h at 1000 cd m⁻² initial luminance of a phosphorescent OLED by substituting the conventional HTM, NPB, with DDPPFPh. Additionally, the 2,4,5,6-tetra(9H-carbazol-9-yl)isophthalonitrile (4CzIPN) green TADF emitter-based OLED displays the enhancement in PE_max from 42.5 to 69.1 lm W⁻¹, CE_max from 54.1 to 78.0 cd A⁻¹, EQE_max from 20.1 to 27.2%, L_max from 12 900 to 44 200 cd m⁻² and LT₅₀ from 195 to 590 h at an initial brightness of 1000 cd m⁻² by replacing NPB with DDPPFPh. Based on these findings, the reported solution-processable HTMs appear to be promising candidates for high-efficiency OLEDs.

中文翻译：

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可溶液加工的吩噻嗪和吩恶嗪取代芴芯纳米结构空穴传输材料，用于实现高效 OLED

可溶液加工的空穴传输材料 (HTM) 是高通量和廉价制造高效有机发光二极管 (OLED) 的关键功能材料。在此，我们成功合成了一系列新的吩噻嗪和吩恶嗪取代芴核基HTMs，即10-hexyl-3-[2,7-di(naphthalen-1-yl)-fluoren-9-ylmethylene] phenoxazine DNFPhe， 10-hexyl-3-[2,7-di(4-(diphenylamino)-phenyl)fluoren-9-ylmethylene] phenoxazine DDPFPhe , 10-hexyl-3-[2,7-di(4-fluorophenyl)-fluoren- 9-基亚甲基]吩恶嗪DFPFPhe , 10-hexyl-3-(2,7-diphenylfluoren-9-ylmethylene) phenoxazine DFPFPhe , 10-hexyl-3-[2,7-di(4-(diphenylamino)phenyl)fluoren-9 -基亚甲基]吩噻嗪DDPPFPh和 10-hexyl-3-[2,7-di(naphthalen-1-yl)fluoren-9-ylmethylene]吩噻嗪DNFPh，并将它们掺入溶液处理的磷光和热激活延迟荧光 (TADF) OLED 中。合成的 HTM 在有机溶剂中表现出优异的溶解性，并显示出纳米纹理的表面形态。与传统的 HTM、 N , N '-bis(naphthalen-1-yl) -N , N '-bis(phenyl)-benzidine ( NPB )相比，这些 HTM 具有高空穴迁移率。通过加入磷光双（4-苯基噻吩并[3,2-c]吡啶基-N,C2'）（乙酰丙酮）铱（III）（PO-01）黄色发光体，我们证明了最大功率效率（PE_max ) 从 41.6 到 45.4 lm W ^-1，电流效率从 39.8 到 50.6 cd A ^-1，外部量子效率 (EQE _max ) 从 12.9 到 19.6%，最大亮度 ( L _max ) 从 15 200 到 19 400 cd m ^-2 ，以及通过用DDPPFPh代替传统的 HTM NPB，磷光 OLED 在 1000 cd m ^-2初始亮度下的151 至 465 h的寿命（LT ₅₀ ） 。此外，基于 2,4,5,6-四（9 H -carbazol -9-yl）间苯二甲腈 ( 4CzIPN ) 绿色 TADF 发射器的 OLED 显示出 PE_最大值从 42.5 提高到 69.1 lm W^-1，CE _max从 54.1 到 78.0 cd A ^-1，EQE _max从 20.1 到 27.2%， L _max从 12 900 到 44 200 cd m ^-2和 LT ₅₀从 195 到 590 h，初始亮度为 1000 cd m ^-2通过将NPB替换为DDPPFPh。基于这些发现，所报道的可溶液加工的 HTM 似乎有望成为高效 OLED 的候选者。