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C 1 ‐Symmetric [Ir(C^N 1 )(C^N 2 )(O^O)]‐ Tris ‐Heteroleptic Iridium(III)‐Complexes with the Preferentially Horizontal Orientation for High‐Performance Near‐Infrared Organic Light‐Emitting Diodes
Author(s) -
Li Wentao,
Wang Baowen,
Miao Tiezheng,
Liu Jiaxiang,
Lü Xingqiang,
Fu Guorui,
Shi Linxi,
Chen Zhongning,
Qian Pengcheng,
Wong WaiYeung
Publication year - 2021
Publication title -
advanced optical materials
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.89
H-Index - 91
ISSN - 2195-1071
DOI - 10.1002/adom.202100117
Subject(s) - iridium , oled , materials science , tris , infrared , luminescence , molecule , analytical chemistry (journal) , photochemistry , optoelectronics , optics , chemistry , physics , nanotechnology , catalysis , biochemistry , organic chemistry , layer (electronics) , chromatography
The development of high‐efficiency near‐infrared (NIR)‐emitting Ir(III)‐complex‐based phosphors for reliable NIR‐OLEDs (near‐infrared organic light‐emitting diodes) is still a formidable challenge. Herein, a molecule‐engineered approach is developed to afford three C 1 ‐symmetric [Ir(C^N 1 )(C^N 2 )(O^O)]‐ tris ‐heteroleptic Ir(III)‐complexes ([Ir(iqbt)(dFppy)(acac)] ( 1 ), [Ir(iqbt)(ppy)(acac)] ( 2 ), and [Ir(iqbt)(dpqx)(acac)] ( 3 )), whose good NIR‐luminescent efficiency (Φ PL = 0.18 for 1 (λ em = 703 nm), 0.26 for 2 (λ em = 715 nm) or 0.28 for 3 (λ em = 707 nm)) originates from the strengthened 3 MLCT contribution (MLCT = metal‐to‐ligand charge transfer). Moreover, the quantitative molecular orientation determination of their doped emitting layers (EMLs) reveals that the preferentially horizontal orientation of the emitting dipoles is beneficial to their highly efficient NIR‐OLEDs with light out‐coupling. Especially for the NIR‐OLED ‐2 with λ em = 715 nm, a high performance (η EQE Max = 5.30% and negligible (<2%) efficiency‐roll‐off) is realized among the reported solution‐processed NIR‐OLEDs based on Ir(III)‐complexes at similar color gamut. This result shows that C 1 ‐symmetric [Ir(C^N 1 )(C^N 2 )(O^O)]‐ tris ‐heteroleptic Ir(III)‐complexes can provide a new platform to low‐cost and large‐area scalable NIR‐OLEDs.