Ir(III) Phosphors Modified with Fluorine Atoms in Pyridine-1,2,4-triazolyl Ligands for Efficient OLEDs Possessing Low-Efficiency Roll-off

Mao, Huiting; Zang, Chun-Xiu; Wen, Lili; Shan, Guo‐Gang; Sun, Haizhu; Xie, Wenfa; Su, Zhong‐Min

doi:10.1021/acs.organomet.6b00753

Cited by 23 publications

(18 citation statements)

References 53 publications

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“…This result further evidences the phosphorescent character of the low-energy emissions. As shown in Figure d, compared with the emissions recorded at rt, the intensities of the low-energy emissions are also greatly enhanced, and the maximum emission wavelengths are blue-shifted at 77 K, which have been widely observed for other phosphorescent organometallic emitters. − According to the previous studies, , phosphorescence emissions should be notably red-shifted by introducing more Pt(II) centers, which is the case for MPt and DPt . However, the emission maximum for TPt shows a slight hypochromic effect with respect to that of DPt .…”

Section: Results and Discussionmentioning

confidence: 60%

Achieving High-Performance Solution-Processed Orange OLEDs with the Phosphorescent Cyclometalated Trinuclear Pt(II) Complex

Yang

Jiao

Dang

et al. 2018

ACS Appl. Mater. Interfaces

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Cyclometalated Pt(II) complexes can show intense phosphorescence at room temperature. Their emission properties are determined by both the organic ligand and the metal center. Whereas most of the related studies focus on tuning the properties by designing different types of organic ligands, only several reports investigate the key role played by the metal center. To address this issue, phosphorescent Pt(II) complexes with one, two, and three Pt(II) centers are designed and synthesized. With more Pt(II) centers, the cyclometalated multinuclear Pt(II) complexes display red-shifted emissions with increased photoluminescence quantum yields. Most importantly, solution-processed organic light-emitting diodes (OLEDs) with the conventional device structure using the multinuclear Pt(II) complexes as emitters show excellent performance. The controlled device based on the conventional mononuclear Pt(II) complex shows a peak external quantum efficiency, current efficiency, and power efficiency of 6.4%, 14.4 cd A, and 12.1 lm W, respectively. The efficiencies are dramatically improved to 10.5%, 21.4 cd A, and 12.9 lm W for the OLED based on the dinuclear Pt(II) complex and to 17.0%, 35.4 cd A, and 27.2 lm W for the OLED based on the trinuclear Pt(II) complex, respectively. To the best of our knowledge, these efficiencies are among the highest ever reported for the multinuclear Pt(II) complex-based OLEDs.

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Section: Results and Discussionmentioning

confidence: 60%

Achieving High-Performance Solution-Processed Orange OLEDs with the Phosphorescent Cyclometalated Trinuclear Pt(II) Complex

Yang

Jiao

Dang

et al. 2018

ACS Appl. Mater. Interfaces

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“…12% and 25% at luminances of 100 and 1000 cd m –2 , respectively. Although −F groups on the ligand of a phosphorescent Ir(III) emitter are generally considered to be detrimental to device stability, a recent report concerning the influence of fluorination on Ir(III) complexes as phosphorescent emitters in OLEDs suggests that rational incorporation of fluorine atoms in the ligands in phosphorescent Ir(III) complexes not only can have little effect on the photophysical and thermal properties but also can fine-tune the performance of the resulting device . All of these results can clearly indicate the great potential of these novel asymmetric heteroleptic Ir(III) phosphorescent emitters with both selenophene and selenide groups.…”

Section: Resultsmentioning

confidence: 99%

Asymmetric Heteroleptic Ir(III) Phosphorescent Complexes with Aromatic Selenide and Selenophene Groups: Synthesis and Photophysical, Electrochemical, and Electrophosphorescent Behaviors

et al. 2018

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With the aim of evaluating the potential of selenium-containing groups in developing electroluminescent (EL) materials, a series of asymmetric heteroleptic Ir(III) phosphorescent complexes (Ir-Se0F, Ir-Se1F, Ir-Se2F, and Ir-Se3F) have been synthesized by using 2-selenophenylpyridine and one ppy-type (ppy = 2-phenylpyridine) ligand with a fluorinated selenide group. To the best of our knowledge, these complexes represent unprecedented examples of asymmetric heteroleptic Ir(III) phosphorescent emitters bearing selenium-containing groups. Natural transition orbital (NTO) analysis based on optimized geometries of the first triplet state (T) have shown that the phosphorescent emissions of these Ir(III) complexes dominantly show π-π* features of the 2-selenophenylpyridine ligand with slight metal to ligand charge transfer (MLCT) contribution. In comparison with their symmetric parent complex Ir-Se with two 2-selenophenylpyridine ligands, these asymmetric heteroleptic Ir(III) phosphorescent complexes can show much higher phosphorescent quantum yields (Φ) of ca. 0.90. Both the hole- and electron-trapping ability of these Ir(III) phosphorescent complexes can be enhanced by selenophene and fluorinated selenide groups to improve their EL efficiencies. The EL abilities of these asymmetric heteroleptic Ir(III) phosphorescent emitters fall in the order Ir-Se3F > Ir-Se2F > Ir-Se1F > Ir-Se0F. The highest EL efficiencies have been achieved by Ir-Se3F in the solution-processed OLEDs with external quantum efficiency (η), current efficiency (η), and power efficiency (η) of 19.9%, 65.6 cd A, and 57.3 lm W, respectively. These encouraging EL results clearly indicate the great potential of selenium-containing groups in developing high-performance Ir(III) phosphorescent emitters.

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“…Notably, the maximum EQE, power efficiency (PE) and luminance efficiency (L max ) values for 8 wt% 1a are either notably better than, or highly competitive with those obtained by Shan, Xie and Su et al for a device doped with a different pentafluoro-phenyl-functionalized heteroleptic Ir complex (max EQE = 10.7%, max PE = 27.6 lm W −1 , L max = 32710 cd m −2 ). 64 At 10,000 cd m −2 an EQE of > 15% is maintained for the device doped with 8 wt% 1a, compared with ca. 10% reported by Shan, Xie and Su et al at this brightness.…”

Section: Computational Studymentioning

confidence: 94%

“…[65][66][67] This is likely related to the ancillary nature of the additional aromatic fluorine atoms on the pentafluorophenyl substituent in 1a, which is also the case for the example presented by Shan, Xie and Su and coworkers. 64 Literature precedent from work on emitters for light emitting electrochemical cells suggests that the intramolecular π−π interactions in 1a may also play a significant role in the good device performance. 33…”

Section: Computational Studymentioning

confidence: 99%

Intramolecular π–π Interactions with a Chiral Auxiliary Ligand Control Diastereoselectivity in a Cyclometalated Ir(III) Complex

Congrave

Batsanov

et al. 2018

Inorg. Chem.

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The application of a chiral auxiliary ligand to control the diastereoselectivity in the synthesis of a cyclometalated iridium(III) complex is presented. The diastereomeric iridium(III) complexes 1a and 1b are reported in which a phenoxyoxazoline auxiliary ligand incorporates a chiral center functionalized with a pendant pentafluorophenyl group. The diastereomers were readily separated and their structural, electrochemical and photophysical properties are discussed. Solution-state NMR data and X-ray crystal structures establish that the pentafluorophenyl group engages in intramolecular π-π interactions. The X-ray analysis reveals that the two diastereomers display very different modes of intramolecular stacking. The variable temperature 19 F NMR data indicate that rotation of the pendant pentafluorophenyl rings in 1b and 1a is a temperature dependent process, and that there is a smaller energy barrier to rotation in 1b compared to 1a. This correlates with variable temperature photoluminescence data which show that upon heating the integrated emission intensity is reduced substantially more for 1b than for 1a, which is ascribed to the enhanced rotation in 1b providing a more easily populated non-radiative pathway compared to 1a. These experimental data are supported by computational calculations. Phosphorescent organic light emitting devices (PhOLEDs) using 1a as the dopant complex give blue-green emission with a high maximum external quantum efficiency (EQE max ) of 25.8% (at ca. 270 cd m −2 ) and with a low efficiency rolloff to 24.9% at 1000 cd m −2 . Our results extend the scope of ligand design for cyclometalated iridium complexes which possess interesting structural and emission properties.

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Ir(III) Phosphors Modified with Fluorine Atoms in Pyridine-1,2,4-triazolyl Ligands for Efficient OLEDs Possessing Low-Efficiency Roll-off

Cited by 23 publications

References 53 publications

Achieving High-Performance Solution-Processed Orange OLEDs with the Phosphorescent Cyclometalated Trinuclear Pt(II) Complex

Achieving High-Performance Solution-Processed Orange OLEDs with the Phosphorescent Cyclometalated Trinuclear Pt(II) Complex

Asymmetric Heteroleptic Ir(III) Phosphorescent Complexes with Aromatic Selenide and Selenophene Groups: Synthesis and Photophysical, Electrochemical, and Electrophosphorescent Behaviors

Intramolecular π–π Interactions with a Chiral Auxiliary Ligand Control Diastereoselectivity in a Cyclometalated Ir(III) Complex

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