714 nm emission with 12.25% efficiency from iridium complexes with low iridium content by the strategy of rigid coordination core and amplifying shell

作者：Wang, Li; Wang, Sai; You, Caifa; Chang, Xiang; Huang, Jingwei; Zhen, Weiqiong; Zhang, Hu; Gan, Xiangqin; Wu, Xiugang^*; Zhu, Weiguo^*

来源：Journal of Materials Chemistry C, 2022, 10(17): 6646-6653.

DOI：10.1039/d2tc00698g

• NEAR-INFRARED EMISSION
• LIGHT-EMITTING-DIODES
• DINUCLEAR PLATINUM COMPLEXES
• DEEP-RED
• ELECTROLUMINESCENT PROPERTIES
• OS(II) PHOSPHORS
• ROLL-OFF
• SALOPHEN
• ISOQUINOLINE

The development of near-infrared (NIR)-emitting phosphorescent emitters are still urgently needed for solution-processed organic light-emitting diodes (SP-OLEDs) with high efficiency, radiant emittance, and low cost. Herein, we designed and synthesized a new iridium complex, namely ((t)BuTPA-DBPz)(2)Ir(acac), with the rigid C<^>N coordinated core of dibenzo[a,c] phenazine (DBPz) and an amplifying peripheral shell of 4,4 '-di(tert-butyl)-triphenylamine ((t)BuTPA) attached at its 3,6-positions. The influence of the rigid DBPz core and big (t)BuTPA shell on the photophysical, electrochemical and electroluminescent properties of ((t)BuTPA-DBPz)(2)Ir(acac) was primarily studied in comparison with the archetype (DBPz)(2)Ir(dpm). The NIR emission peaked at 714 nm with an outstanding external quantum efficiency of 12.25% and a recorded radiant emittance of 45 330 mW Sr-1 m(-2) was observed in the ((t)BuTPA-DBPz)(2)Ir(acac)-doped devices at an optimized dopant ratio of 8 wt%. The EQE is 1.57 times that of (DBPz)(2)Ir(dpm)-doped devices. Moreover, this NIR light-emitting device contains an Ir(iii) content as low as 0.68 wt% and exhibits a bright NIR emission at 714 nm with outstanding efficiency and radiant emittance. Our results indicate that the NIR-emitting OLEDs with high efficiency, radiant emittance and low cost should be realized by developing core-shell type Ir(iii) complexes with a rigid C<^>N coordinate core and an amplifying shell.

• 单位
  常州大学