714 nm emission with 12.25% efficiency from iridium complexes with low iridium content by the strategy of rigid coordination core and amplifying shell. Issue 17 (12th April 2022)

• Record Type: Journal Article
• Authors: Wang, Li; Wang, Sai; You, Caifa; Chang, Xiang; Huang, Jingwei; Zhen, Weiqiong; Zhang, Hu; Gan, Xiangqin; Wu, Xiugang; Zhu, Weiguo
• Is Part Of: Journal of materials chemistry. Volume 10:Issue 17(2022)
• Page Start: 6646
• Page End: 6653
• Publication Date: 2022-04-12
• Subjects: Materials -- Periodicals; Chemistry, Analytic -- Periodicals; Optical materials -- Research -- Periodicals; Electronics -- Materials -- Research -- Periodicals; 543.0284
• DOI: 10.1039/d2tc00698g
• Languages: English
• ISSNs: 2050-7526

Abstract

Abstract : A novel core–shell-typed Ir(iii ) complex with a rigid C^N coordinated core of DBPz and an amplifying peripheral shell of t BuTPA. Its doped OLEDs exhibited a 714 nm emission with an outstanding EQE of 12.25% and a recorded radiance emittance of 45 330 mW Sr −1 m −2 . Abstract : 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.