4-Diphenylaminocarbazole: Switching Substituent Position for Voltage Reduction and Efficiency Enhancement of OLEDs,ACS Applied Materials & Interfaces

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4-Diphenylaminocarbazole: Switching Substituent Position for Voltage Reduction and Efficiency Enhancement of OLEDs
ACS Applied Materials & Interfaces ( IF 8.3 ) Pub Date : 2018-02-26 00:00:00 , DOI: 10.1021/acsami.7b18044
Shahid Ameen _{1,

2,

3} , Seul Bee Lee _{1,

2} , Yong Guk Lee ₁ , Sung Cheol Yoon _{1,

2} , Jaemin Lee _{1,

2} , Changjin Lee _{1,

2}

Affiliation

Simple but exceptionally efficient 4-diphenylaminocarbazole host material, 4-DPACz, is presented and compared with its positional isomer, 1-DPACz. The shift of diphenylamino substituent from the 1-position to 4-position of carbazole resulted in an increase in the HOMO energy level as well as an increase in triplet energy level. Having a high triplet energy level (2.76 eV) and well-matched HOMO energy level (−5.61 eV), 4-DPACz showed reduced driving voltage and higher efficiencies for solution-processed green PhOLEDs compated to PVK as well as 1-DPACz. Maximum luminous, power, and external quantum efficiencies reaching to 47.9 cd A^–1, 25.2 lm W^–1, and 14.3%, respectively, were achieved with a device configuration of [ITO/PEDOT:PSS/4-DPACz:Ir(mppy)₃/TPBi/CsF/Al]. Additional enhancement of efficiencies of 4-DPACz was verified when incorporating another dopant, Ir(Si-bppy)₂(acac), resulting in 59.1 cd A^–1, 29.5 lm W^–1, and 15.8%. Furthermore, reduced efficiency roll-off was clearly observed for 4-DPACz compared with PVK. Such improved device characteristics of 4-DPACz were attributed to its high hole mobility and charge balance inside the emitting layer therof. The excellent results using such a simple-structured 4-DPACz could promote various applications of this 4-DPACz unit as a building block structure for further possible oligomeric, dendritic, and polymeric materials.

中文翻译：

4-二苯基氨基咔唑：用于降低电压和提高OLED效率的开关取代基位置

介绍了一种简单但效率极高的4-二苯基氨基咔唑主体材料4-DPACz，并将其与位置异构体1-DPACz进行了比较。二苯氨基取代基从咔唑的1位到4位转移导致HOMO能级增加以及三重态能级增加。具有高三重态能级（2.76 eV）和良好匹配的HOMO能级（-5.61 eV），对于与PVK和1-DPACz相适应的溶液处理绿色PhOLED，4-DPACz显示出降低的驱动电压和更高的效率。最大发光，功率和外部量子效率达到47.9光盘^-1，25.2流明w ^ ^-1，和14.3％，分别用的[ITO / PEDOT设备配置实现：PSS / 4-DPACz：IR（mppy ）₃/ TPBi / CsF / Al]。掺入的掺杂剂的另一个时4- DPACz的效率的附加增强证实，IR（SI-bppy）₂（ACAC），导致59.1光盘^-1，29.5流明w ^ ^-1，和15.8％。此外，与PVK相比，4-DPACz的效率下降明显降低。4-DPACz的这种改进的器件特性归因于其高空穴迁移率和发射层内的电荷平衡。使用这种简单结构的4-DPACz产生的优异结果可以促进该4-DPACz单元作为构建模块结构的各种应用，以用于进一步可能的低聚，树枝状和聚合材料。

更新日期：2018-02-26

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