C1-Symmetrical [Ir(C^N1)(C^N2)(N^O)]-tris-heteroleptic Ir(iii)-complexes with one strong N^O-ancillary π-donor for efficient all-solution-processed near-infrared (NIR) polymer light-emitting diodes (PLEDs). Issue 8 (31st January 2022)

• Record Type: Journal Article
• Authors: Zhang, Yan; Wang, Baoweng; Liu, Jiaxiang; Lü, Xingqiang; Fu, Guorui; Li, Wentao; Wong, Wai-Yeung
• Is Part Of: Journal of materials chemistry. Volume 10:Issue 8(2022)
• Page Start: 3178
• Page End: 3187
• Publication Date: 2022-01-31
• Subjects: Materials -- Periodicals; Chemistry, Analytic -- Periodicals; Optical materials -- Research -- Periodicals; Electronics -- Materials -- Research -- Periodicals; 543.0284
• DOI: 10.1039/d1tc05662j
• Languages: English
• ISSNs: 2050-7526

Abstract

Abstract : Upon the usage of Ba/Al instead of LiF/Al, [Ir(iqbt)(btp)(pbi)] exhibited an attractive η MaxEQE of 4.24% for its reliable all-solution-processed NIR-PLEDs. Abstract : Among reliable vacuum-deposited or solution-processed NIR-OLEDs/PLEDs doped with NIR-emitting iridium(iii )-complexes, high-performance achievement of their all-solution-processed NIR-PLEDs remains a great challenge. In this study, owing to the forceful electronic perturbation achieved by incorporation of the strong π-donating N^O-ancillary ligand Hpbi, its NIR-emitting tris-heteroleptic [Ir(iqbt)(btp)(pbi)] (2 ) does not exhibit an augmented 3 MLCT effect in comparison to the corresponding bis-heteroleptic [Ir(iqbt)2 (pbi)] (1 ) counterpart. Nonetheless, the transition dipole (TD) effect through k r ∈ TD 2 dominates, rendering the k r and the resulting Φ PL (0.36; λ em = 714 nm) of 2 larger than those of 1 ( Φ PL = 0.29; λ em = 712 nm). Moreover, through electron injection/transport facilitated by the composite cathode Ba/Al instead of LiF/Al, better electroluminescent properties ( η MaxEQE = 3.53 (1 ) versus 4.24% (2 ) and negligible (<5%) efficiency roll-off) are realized for their all-solution-processed NIR-PLEDs. This result shows that: (i) both the 3 MLCT and TD effects should be simultaneously taken into account in challenging the intrinsic low-efficiency of Ir(iii )-complex-based NIR-emitters; (ii) in dependent on electron injection/transport facilitation with one specific composite cathode, high-performance and reliable all-solution-processed NIR-PLEDs especially based on [Ir(C^N 1 )(C^N 2 )(L^X)]-tris-heteroleptic Ir(iii )-complexes could desirably be approached.