Deep-Red and Near-Infrared Iridium Complexes with Fine-Tuned Emission Colors by Adjusting Trifluoromethyl Substitution on Cyclometalated Ligands Combined with Matched Ancillary Ligands for Highly Efficient Phosphorescent Organic Light-Emitting Diodes

Abstract

Six novel Ir(C^N)2(L^X)-type heteroleptic iridium complexes with deep-red and near-infrared region (NIR)-emitting coverage were constructed through the cross matching of various cyclometalating (C^N) and ancillary (LX) ligands. Here, three novel C^N ligands were designed by introducing the electron-withdrawing group CF3 on the ortho (o-), meta (m-), and para (p-) positions of the phenyl ring in the 1-phenylisoquinoline (piq) group, which were combined with two electron-rich LX ligands (dipba and dipg), respectively, leading to subsequent iridium complexes with gradually changing emission colors from deep red (≈660 nm) to NIR (≈700 nm). Moreover, a series of phosphorescent organic light-emitting diodes (PhOLEDs) were fabricated by employing these phosphors as dopant emitters with two doping concentrations, 5% and 10%, respectively. They exhibited efficient electroluminescence (EL) with significantly high EQE values: >15.0% for deep red light0 (λmax = 664 nm) and >4.0% for NIR cases (λmax = 704 nm) at a high luminance level of 100 cd m−2. This work not only provides a promising approach for finely tuning the emission color of red phosphors via the easily accessible molecular design strategy, but also enables the establishment of an effective method for enriching phosphorescent-emitting molecules for practical applications, especially in the deep-red and near-infrared region (NIR).

Designing Poly(arylene ether sulfone)s with Platinum(II) Acetylide to Regulate Photophysical Properties toward Solid-State Nonlinear Limiters

“…A longer τ P is exhibited by series 2 compared to that of series 1 due to the lower and more stable energy of the T 1 state (in line with subsequent theoretical calculations), enabling electrons to remain in the T 1 state for an extended duration. Meanwhile, lower Φ P is exhibited by PAES-Pt-2-(3–15%) with longer conjugation, indicating that a greater portion of energy dissipates through nonradiative pathways during the transition instead of being emitted as phosphorescence . However, Fs-Pt-1 exhibits a lower Φ P than that of Fs-Pt-2, and a more significant enhancement in Φ P is observed after polymerization.…”

“…Meanwhile, lower Φ P is exhibited by PAES-Pt-2-(3−15%) with longer conjugation, indicating that a greater portion of energy dissipates through nonradiative pathways during the transition instead of being emitted as phosphorescence. 36 However, Fs-Pt-1 exhibits a lower Φ P than that of Fs-Pt-2, and a more significant enhancement in Φ P is observed after polymerization. This may be attributed to the strong intermolecular interactions of Fs-Pt-1, which make it more prone to aggregation and triplet-state quenching.…”

Red and Near Infrared Emissive Bis‐Tridentate Ir(III) Phosphors for Organic Light Emitting Diodes

“…Figure 7d). Listed below were selective Os(II), Ir(III), and Pt(II) based NIR emitters showing emission peak wavelength at ∼700 nm: CNIr (𝜆 max = 690 nm, EQE max = 2.75%), [41] Ir(dpa-piq-CN) 2 (acac) (𝜆 max = 692 nm, EQE max = 12.5%), [42] Ir(ttiq) 2 (tmd) (𝜆 max = 696 nm, EQE max = 13.7%), [43] (o-CF 3 piq) 2 Ir(dipg) (𝜆 max = 704 nm, EQE max = 4.6%), [44] Ir3 (𝜆 max = 708 nm, EQE max = 13.7%), [45] ( t BuTPA-DBPz) 2 Ir(acac) (𝜆 max = 714 nm, EQE max = 12.3%), [46] Ir4 (𝜆 max = 714 nm, EQE max = 1.08%), [47] (PPz-11,12-DO) 2 Ir(acac) (𝜆 max = 724 nm, EQE max = 4.14%), [48] 2 (𝜆 max = 760 nm, EQE max = 4.5%), [49] TPAIr (𝜆 max = 768 nm, EQE max = 3.34%), [10e] Ir(mpbqx-g) 2 (acac) (𝜆 max = 780 nm, EQE max = 2.2%), [50] 3 (𝜆 max = 725 nm, EQE max = 2.2%), [51] Pt-3 (𝜆 max = 740 nm, EQE max = 10.8%), [ 16a ] D3 (𝜆 max = 754 nm, EQE max = 3.0%), [ 16b ] (BOiqn) 2 Pt (𝜆 max = 656 nm, EQE max = 3.8%), [ 16c ] and tz2 (𝜆 max = 746 nm, EQE max = 4.2%). [ 9a ] It is also worth noting that both the structureless emission profile and low efficiency roll-offs are observed at high current densities with our bis-tridentate Ir(III) emitters.…”

Unprecedented hetero-coordinated Ir(C^N)2tmd complexes containing both five- and six-membered Ir-(C^N) rings based on phenanthrylpyridine ligands: syntheses, crystal structures and photophysical properties

“…[11][12][13] A gamut of red or near-infrared (NIR) Ir(III) complexes, e.g. homoleptic Ir(C^N) 3 [14][15][16][17] and heteroleptic Ir(C^N) 2 (L^X) complexes, [18][19][20][21][22][23] have been reported, all of which exhibit impressive photophysical properties. In particular, given the diversity of heteroleptic Ir(III) complexes with cooperating C^N main ligands and L^X auxiliary ligands, the characteristics of Ir(C^N) 2 (L^X) have been extensively excavated.…”