Blue-emitting bis-tridentate Ir(<scp>iii</scp>) phosphors: OLED performances <i>vs.</i> substituent effects

Kuo, Hsin‐Hung; Hsu, Ling-Yang; Tso, Jen-Yung; Hung, Wen‐Yi; Liu, Shih-Hung; Chou, Pi‐Tai; Wong, Ken‐Tsung; Zhu, Ze‐Lin; Lee, Chun‐Sing; Jen, Alex K.‐Y.; Chi, Yun

doi:10.1039/c8tc03194k

Cited by 21 publications

(10 citation statements)

References 57 publications

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“…Their pincer carbene chelates possess a planar configuration, from which there existed an identical C–Ir–C bite angle of approx 156°, and the peripheral Ir–C carbene distances (i.e., 2.043–2.065 Å) are found to be slightly longer than those of the central Ir–C distance (1.950–1.957 Å). These metric parameters are consistent with almost all relevant bis-tridentate Ir(III) complexes reported in the literature, − suggesting that the imidazo[4,5- b ]pyridin-2-ylidenes imposed no obvious structural changes from that of imidazolylidene analogues. Moreover, the 2,6-diaryoxypyridine cyclometalate took a puckered arrangement, and the torsional angle between the central pyridinyl plane of this chelate and phenyl fragment of the trans-oriented carbene pincer chelate was calculated to be 61.0 and 62.3° for Dap-1 and 2 , respectively.…”

Section: Resultssupporting

confidence: 87%

Rational Tuning of Bis-Tridentate Ir(III) Phosphors to Deep-Blue with High Efficiency and Sub-microsecond Lifetime

Tai

Gnanasekaran

Chen

et al. 2021

ACS Appl. Mater. Interfaces

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A new class of bis-tridentate Ir(III) complexes (Dap-1−4) was synthesized using carbene pincer pro-chelates PC1•H 3 (PF 6 ) 2 or PC2•H 3 (PF 6 ) 2 with either imidazolylidene or imidazo [4,5-b]pyridin-2-ylidene appendages, together with a second cyclometalating 2,6-diaryoxypyridine chelate, L1H 2 and L2H 2 , differed by a NMe 2 donor at the central pyridinyl fragment. The respective emission tuning between the ultraviolet and blue region was rationalized using time-dependent density functional theory (TD-DFT) approaches. Next, a highly efficient blue emitter (Dap-5) was synthesized by concomitant addition of two methyl groups and a single CF 3 substituent at the central phenyl and peripheral imidazo[4,5-b]pyridin-2-ylidene entities of the carbene pincer chelate, respectively. The organic light-emitting diode (OLED) device with 15 wt % Dap-5 in DPEPO shows electroluminescence at 468 nm and with CIE (0.14, 0.15) and a max external quantum efficiency (max EQE) of 16.8% with low efficiency roll-off (EQE of 14.4% at 1000 cd m −2 ); the latter is attributed to the relatively shortened triplet excitedstate radiative lifetime. These results highlight the adequateness of bis-tridentate Ir(III) phosphors in fabrication of practical blue-emitting OLEDs.

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Section: Resultssupporting

confidence: 87%

Rational Tuning of Bis-Tridentate Ir(III) Phosphors to Deep-Blue with High Efficiency and Sub-microsecond Lifetime

Tai

Gnanasekaran

Chen

et al. 2021

ACS Appl. Mater. Interfaces

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“…The carbene pincer chelate possesses an essentially planar arrangement, from which the C–Ir–C bite angle is measured to be 156.09(13)° and the central Ir–C(phenyl) distance [1.974(3) Å] is shorter than those of the peripheral Ir–C(carbene) distances [i.e., 2.041(3) Å and 2.043(3) Å]. This pattern of the Ir–C distances is in agreement with that of other bis-tridentate iridium complexes reported in the literature. − Moreover, the PzpyCz ancillary exhibited a slightly rotated coordinative arrangement, in which the torsional angle between this carbazolyl fragment and the central pyridyl fragment was measured to be ∼39°. Hence, this chelate configuration increased the trans C1–Ir–N3 bite angle to ∼167°.…”

Section: Resultssupporting

confidence: 85%

Efficient Blue Electrophosphorescence and Hyperphosphorescence Generated by Bis-tridentate Iridium(III) Complexes

et al. 2022

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Four blue-emissive iridium(III) complexes bearing a 3,3′-(1,3-phenylene)bis[1-isopropyl-6-(trifluoromethyl)-3H-imidazo[4,5-b]pyridin-2-ylidene]-based pincer chelate, which are derived from PXn·H3(PF6)2, where n = 1–4, and a cyclometalating chelate given from 9-[6-[5-(trifluoromethyl)-2λ2-pyrazol-3-yl]pyridin-2-yl]-9H-carbazole [(PzpyCz)H2], were successfully synthesized and employed as both an emissive dopant and a sensitizer in the fabrication of organic light-emitting diode (OLED) devices. These functional chelates around a IrIII atom occupied two mutually orthogonal coordination arrangements and adopted the so-called bis-tridentate architectures. Theoretical studies confirmed the dominance of the electronic transition by the pincer chelates, while the dianionic PzpyCz chelate was only acting as a spectator group. Phosphorescent OLED devices with [Ir(PX3)(PzpyCz)] (B3) as the dopant gave a maximum external quantum efficiency (EQE) of 21.93% and CIE xy of (0.144, 0.157) and was subjected to only ∼10% of roll-off in efficiency at a high current density of 1000 cd m–2. Blue-emissive narrow-band hyperphosphorescence was also obtained using B3 as an assistant sensitizer and ν-DABNA as a terminal emitter, giving both an improved EQE of 26.17% and CIE xy of (0.116, 0.144), confirming efficient Förster resonance energy transfer in this hyperdevice.

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“…158 Various methodologies for fine-tuning the electronic transitions of bis-tridentate Ir(III) complexes for high performance and durable phosphorescent OLEDs are being developed at present. [159][160][161][162] 3.3.2. Bridged diiridium complexes.…”

Section: Rigid Structure For Restricted Intramolecular Motionmentioning

confidence: 99%

Cyclometalated Ir(iii) complexes towards blue-emissive dopant for organic light-emitting diodes: fundamentals of photophysics and designing strategies

Lee

Han

2020

Inorg. Chem. Front.

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Blue-emitting bis-tridentate Ir(iii) phosphors: OLED performances vs. substituent effects

Cited by 21 publications

References 57 publications

Rational Tuning of Bis-Tridentate Ir(III) Phosphors to Deep-Blue with High Efficiency and Sub-microsecond Lifetime

Rational Tuning of Bis-Tridentate Ir(III) Phosphors to Deep-Blue with High Efficiency and Sub-microsecond Lifetime

Efficient Blue Electrophosphorescence and Hyperphosphorescence Generated by Bis-tridentate Iridium(III) Complexes

Cyclometalated Ir(iii) complexes towards blue-emissive dopant for organic light-emitting diodes: fundamentals of photophysics and designing strategies

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