New oxazoline- and thiazoline-containing heteroleptic iridium(iii) complexes for highly-efficient phosphorescent organic light-emitting devices (PhOLEDs): colour tuning by varying the electroluminescence bandwidth

Chao, Kai; Shao, Kui‐Zhan; Peng, Tai; Zhu, Dongxia; Wang, Yue; Liu, Yu; Su, Zhong‐Min

doi:10.1039/c3tc31463d

Cited by 27 publications

(34 citation statements)

References 55 publications

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“…This phenomenon suggests that the dopant 1 40 and 2 can be used as the media for hole injecting into and transporting in the TPBi host layers while their role in doped CBP layer is just trapping the electron from CBP sites. These results are consistent with our expected bipolar EMLs composed of TPBi and 1 or 2, in which the dopant (1 or 2) and the host 45 (TPBi) molecules can serve as two convenient channels for transporting both holes and electrons, and they will facilitate holes and electrons injection and conduction across the EML by hopping between the adjacent dopant and host molecules respectively, and then achieve balanced charge fluxes, resulting 50 in high device performance.…”

Section: Charge Carrier Injection and Transport Propertiessupporting

confidence: 90%

“…The oxidation process is analogous to removing an electron from the metal-centered HOMO level, 14 therefore the oxidation of complexes 1 and 2 can be assigned to the Ir Ⅳ /Ir Ⅲ oxidation. 11b Both of them undergoes 45 reversible one-electron oxidation processes and the HOMO levels of complex 1 and 2 are determined to be -5.57 and -5.33eV respectively. In addition, the reduction process is equivalent to adding an electron to the ligand-centered LUMO level.…”

Section: Resultsmentioning

confidence: 99%

“…45 Anhydrous hexane was distilled with sodium benzophenone ketyl under nitrogen atmosphere and degassed by the freeze-pumpthaw method. All glasswares, syringes, magnetic stirring bars and needles were dried in a convection oven for at least 4 hours.…”

Section: General Informationmentioning

confidence: 99%

“…Secondly, a slight emission at 420-460 nm due to the CBP host plus the dominant peak being detectable in the EL spectrum of C1 or C2 respectively (Fig. 5b inset), suggests that part of 45 recombination of injected holes and electrons occurs at the CBP host molecule sites and then the excited energy is incomplete transfer from CBP to 1 or 2 in the C-series devices, even though they employ rather high doping concentration of 15 wt%. Generally, direct charge recombination should be a more effective way to achieve high efficiency in PhOLEDs, because energy losses during the host-dopant energy transfer process can 5 be avoided.…”

Section: Characterization Of Phosphorescent Oledsmentioning

confidence: 99%

“…However, up to now, there are rare pincer Ir complexes being applied to fabricating OLEDs, which generally 40 showed moderate efficiencies {≈ 5 lm W −1 (Power Efficiency, PE) or 8 % (External Quantum Efficiency, EQE) for blue-green emission, ≈ 10 lm W −1 or 10 % for green or orange emission} and rather high driving voltages (> 10 V reaching the luminance of 500 cd m −2 ). 4b,c 45 On the other hand, for the most PhOLEDs with the doping system based on the fluorescent host and the phosphorescent dopant emitter, the hole and/or electron injection into the highest occupied molecular orbital (HOMO) and/or the lowest unoccupied molecular orbital (LUMO) of the dopant and then 50 direct charge recombination in the dopant, is considered more efficient for the formation of excitons than host-to-dopant energy transfer. 5 Obviously, this direct charge recombination process can eliminate not only the need to overcome the large energy barriers between the charge transport layers and the emitting layer (EML) 55 resulted from the wide HOMO−LUMO gap of the host, but also the energy losses during the exothermic host-dopant energy transfer process.…”

Section: Introductionmentioning

confidence: 99%

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High performance blue-green and green phosphorescent OLEDs based on iridium complexes with N^C^N-coordinated terdentate ligands

et al. 2015

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Graphical Abstract:Series of highly efficient phosphorescent organic light-emitting diodes (PhOLEDs) based on two iridium complexes (1 and 2) constructed by the N^C^N-coordinated terdentate ligands have been achieved. They exhibit the high peak power efficiency (PE) and external quantum efficiency (EQE) values of 35.5 lm W −1 & 15.8 % for blue-green emission, 47.4 lm W −1 & 16.7 % for green emission, which maintain the high level of 19.2 lm W −1 & 14.5 % and 30.6 lm W −1 & 16.1 % at rather high and practical luminance of 500 cd m −2 with the low driving voltages of less than 6 V. The appropriate selection of a prominent electron-transport molecule TPBi as a host to matching the dopant molecules (1 or 2) that possess the obvious hole-transport ability is critical in the remarkable EL-performance improvement on previous reports.Highly efficient phosphorescent organic light-emitting diodes (PhOLEDs) based on two iridium complexes constructed by the N^C^N-coordinated terdentate ligands (also called pincer ligands) have been achieved. They exhibit the high peak power efficiency (PE) and external quantum efficiency (EQE) values of 35.5 lm W −1 & 15.8 % for blue-green emission, 47.4 lm W −1 & 16.7 % for green emission, 10 which maintain the high level of 19.2 lm W −1 & 14.5 % and 30.6 lm W −1 & 16.1 % at rather high and practical luminance of 500 cd m −2 with the low driving voltages of less than 6 V. These values show almost a twofold enhancement over the most efficient PhOLEDs based on the pincer iridium complexes ever reported. Here, the appropriate selection of a prominent electron-transport molecule TPBi as a host to matching the dopant molecules (1 or 2) that possess sufficient hole-transport ability is critical in the 15 remarkable EL-performance improvement on previous reports. We will present a comprehensive investigation that not only encompasses the conventional thermal, photophysical and electrochemical properties of both complexes, but also emphatically studies the charge carrier injecting/transporting and electroluminescent (EL) characteristics of two phosphorescent emitters doped in different host.

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Section: Charge Carrier Injection and Transport Propertiessupporting

confidence: 90%

Section: Resultsmentioning

confidence: 99%

Section: General Informationmentioning

confidence: 99%

Section: Characterization Of Phosphorescent Oledsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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High performance blue-green and green phosphorescent OLEDs based on iridium complexes with N^C^N-coordinated terdentate ligands

et al. 2015

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Optical Functional Materials Inspired by Biology

Shang

et al. 2015

Advanced Optical Materials

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To learn from nature for the rational design of optical devices, the chemical and physical aspects of textures of these natural organisms should be systematically unraveled. Then the basic mechanisms as to how these structural units interact with light must be understood in depth. Finally, whether these morphologies can be fabricated by templating methods, by the current top-down methods, or by selfassembly methods should be well assessed. Up to now, biotemplating methods that take advantage of the physicochemical interactions between organic skeletons and the target solid-state materials are broadly adopted, as they are both cost and time effective. Many natural organisms have been successfully used as biotemplates to fabricate artifi cial photonic materials, including butterfl y wings, [20][21][22][23] beetles, [ 24,25 ] plant leaves, [ 26,27 ] and diatoms. [ 28,29 ] The biotemplating method can not only maintain the morphology of the natural organism, but also mimic the optical functions of the biological species. In addition, a wide range of high-quality photonic nanostructures have been fabricated using top-down methods, such as direct laser writing, photoetching, soft-lithography, and electron beam lithography. [ 10,[30][31][32] Some self-assembly systems can also provide us with novel photonic templates for the fabrication of functional materials, such as the opal structure selfassembled by polymer or silica spheres, [ 33,34 ] and some cubic phases self-assembled in block copolymer systems. [35][36][37] Inspired by natural organisms, researchers have achieved great progress in developing photonic materials in recent years. Many natural species, including birds, [ 3,38,39 ] insects (especially Lepidoptera and beetles), [ 3,[40][41][42][43] plants, [ 44,45 ] and aquatic organisms, [ 29,46 ] have a striking appearance with vivid structural colors originating from elaborate photonic crystals (PCs). PCs are periodic photonic nanostructures at the visible light wavelength scale that can affect the propagation of light. Inspired by these vivid structural colors, optical materials with photonic microstructures and brilliant color have been fabricated with applications in areas covering the cosmetics industry, [ 47 ] textile industry, [ 48 ] printing, [ 49 ] displays, [ 16 ] and security labeling. [ 5 ] As we know, structural colors originate from the interaction of light with various elaborate photonic structures, and are mainly determined by three structural parameters: the refractive index ratio, the volume fraction, and the unit cell size. [ 24 ] For certain optical systems, the photonic structural parameters can be tuned by exerting external fi elds to which the compositions are responsive, such as pH, [ 22,50 ] electromagnetic fi elds, [ 23,51 ] thermal fi elds, [ 52,53 ] gases, [ 54,55 ] and so on. By quantifying the

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Automatic Screen‐out of Ir(III) Complex Emitters by Combined Machine Learning and Computational Analysis

Cheng

Liu

Jiang

et al. 2023

Advanced Optical Materials

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The organic light‐emitting diode (OLED) has gained widespread commercial use, yet there is a continuous need to identify innovative emitters that offer higher efficiency and a broader color gamut. To effectively screen out promising OLED molecules that are yet to be synthesized, representation learning aided high throughput virtual screening (HTVS) over millions of Ir(III) complexes, which are prototypical types of phosphorescent OLED material constructed via a random combination of 278 reported ligands. This study successfully screens out a decent amount of promising candidates for both display and lighting purposes, which are worth further experimental investigation. The high efficiency and accuracy of this model are largely attributed to the pioneering attempt of using representation learning to organic luminescent molecules, which is initiated by a pre‐training procedure with over 1.6 million 3D molecular structures and frontier orbital energies predicted via semi‐empirical methods, followed by a fine‐tuning scheme via the quantum mechanical computed properties over around 1500 candidates. Such workflow enables an effective model construction process that is otherwise hindered by the scarcity of labeled data and can be straightforwardly extended to the discovery of other novel materials.

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New oxazoline- and thiazoline-containing heteroleptic iridium(iii) complexes for highly-efficient phosphorescent organic light-emitting devices (PhOLEDs): colour tuning by varying the electroluminescence bandwidth

Cited by 27 publications

References 55 publications

High performance blue-green and green phosphorescent OLEDs based on iridium complexes with N^C^N-coordinated terdentate ligands

High performance blue-green and green phosphorescent OLEDs based on iridium complexes with N^C^N-coordinated terdentate ligands

Optical Functional Materials Inspired by Biology

Automatic Screen‐out of Ir(III) Complex Emitters by Combined Machine Learning and Computational Analysis

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