Assistant dopant system in solution processed phosphorescent OLEDs and its mechanism reveal

作者：Hu, Juntao^*; Hu, Sheng; Lu, Chaochao; Huang, Yang; Xu, Kai; Wang, Xianghua^*

来源：Optical Materials, 2018, 75: 513-520.

DOI：10.1016/j.optmat.2017.11.007

• Organic light-emitting diodes
• Thermally activated delayed fluorescence
• Assistant dopant
• Energy transfer process

We have developed an assistant dopant system in phosphorescent OLEDs. The system is consisted of a conventional host material 4,4'-Bis(carbazol-9-yl)biphenyl (CBP), a thermally activated delayed fluorescence (TADF) 2,4,5,6-tetrakis(carbazol-9-yl)-1,3-dicyanobenzene (4CzIPN) and a red phosphor Bis[2-(4-n-hexylphenyl)quinoline](acetylacetonate)iridium(III) (Hex-Ir(phq)(2)(acac)), it has achieved maximum current efficiency and external quantum efficiency of 21.52 cd/A and 9.22%, respectively. The intrinsic mechanism and energy transfer process in the system have been discussed in detail. Moreover, a satisfactory critical current density Jo of 106.1 mA/cm(2) has been obtained when the assistant dopant concentration ascends to a suitable level, which indicated low efficiency roll-off of the device. By investigating the exciton generation mechanism and the transient electroluminescence (EL), the main cause of the improvement has been revealed.

• 出版日期2018-1
• 单位合肥工业大学