Inter-Ligand Energy Transfer and Related Emission Change in the Cyclometalated Heteroleptic Iridium Complex:  Facile and Efficient Color Tuning over the Whole Visible Range by the Ancillary Ligand Structure

You, Youngmin; Park, Soo Young

doi:10.1021/ja052880t

Cited by 462 publications

(321 citation statements)

References 12 publications

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“…[6][7][8][9][10] Several groups have demonstrated tuning of the phosphorescence wavelength from blue to red by functionalization of the ligands with electron withdrawing and electron donating substituents. [11][12][13] Nevertheless, no attempts were made to tune the colour purity by decreasing the emission bandwidth, which of course is attractive for both fundamental research and practical applications. Therefore, in this communication we report a novel approach for tuning bandwidth by modulating the LUMO levels of the ancillary ligand.…”

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confidence: 99%

Highly phosphorescent perfect green emitting iridium(iii) complex for application in OLEDs

et al. 2007

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A novel iridium complex, [bis-(2-phenylpyridine)(2-carboxy-4-dimethylaminopyridine)iridium(III)] (N984), was synthesized and characterized using spectroscopic and electrochemical methods; a solution processable OLED device incorporating the N984 complex displays electroluminescence spectra with a narrow bandwidth of 70 nm at half of its intensity, with colour coordinates of x = 0.322; y = 0.529 that are very close to those suggested by the PAL standard for a green emitter.Organic light emitting diodes (OLEDs) are becoming increasingly successful as a new display technology. 1,2 Although OLED displays have reached commercialization, there is still a need for improvement of the efficiency, colour purity and stability. This is true for multilayered OLEDs prepared via vacuum evaporation and even more so for OLED architectures obtained via solution processing. The latter technique offers a more economic production route and hence is of great interest for the more widespread application of the OLED technology. The introduction of iridium(III) containing complexes led to very efficient multilayered OLEDs, reaching internal conversion efficiency of almost 100%. 3 These high efficiencies originate from the strong spin orbit coupling present in these heavy metal complexes which makes it possible for both singlet and triplet excitons generated to decay radiatively. 4,5 A large number of iridium complexes have been utilized for this purpose, which are mostly based on the cyclometalating ligand 2-phenylpyridine (ppy) with an auxiliary ligand such as acetylacetonate (acac) or picolinate (pic). [6][7][8][9][10] Several groups have demonstrated tuning of the phosphorescence wavelength from blue to red by functionalization of the ligands with electron withdrawing and electron donating substituents. [11][12][13] Nevertheless, no attempts were made to tune the colour purity by decreasing the emission bandwidth, which of course is attractive for both fundamental research and practical applications. Therefore, in this communication we report a novel approach for tuning bandwidth by modulating the LUMO levels of the ancillary ligand.The N984 complex was synthesized in one step by reacting the dimeric iridium(III) complex [Ir(ppy) 2 (Cl)] 2 with methyl-dimethylamino-picolinate and sodium carbonate in 2-ethoxy-ethanol affording the N984 compound as a yellow powder.{ The 1 H NMR spectrum of the N984 complex shows 19 resonance signals (two doublets (d), five doublet of doublets (dd), six doublet of doublet of doublets (ddd) and six doublet of triplets (dt); see Fig. S1) in the aromatic region. The pyridine 6-H protons of the 2-phenylpyridine ligands are assigned to ddd at d 7.64 and d 8.82 on the basis of the distinctive pattern of the coupling constants expected for these substituted pyridines (J 3,6 0.8, J 4,6 1.6 and J 5,6 5.8). The different magnetic environments of these protons are a result of the trans geometry of the pyridine rings which directs one 6-H proton towards the 4-dimethylaminopyridine ring and the other towards the car...

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Highly phosphorescent perfect green emitting iridium(iii) complex for application in OLEDs

et al. 2007

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“…In recent years, varioust ypes of cyclometalated Ir(III) complexes have been developed, such as homoleptic complexes, heteroleptic neutral complexes and cationic complexes [4][5][6]. In contrast to the most famous substituted phenylpyridine ligands, few examples of naphthalenylpyridine iridium complexes have been reported [7,8].…”

Section: Discussionmentioning

confidence: 99%

Crystal structure of 2-(2-naphthyl)-4,6-dimethylpyrimidine, C16H14N2

Qiang¹,

Si²,

Dong³

et al. 2011

Zeitschrift Für Kristallographie - New Crystal Structures

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“…More importantly, its triplet energy E T (2.55 eV) 40 is too low for sky-blue phosphors such as FIrpic. 41 Phosphine oxide (PO) 15,16,[42][43][44][45][46][47][48][49] and sulfone (SO 2 ) 50, 51 derivatives with high triplet energy have emerged as host materials for blue electrophosphorescence and have also been successfully utilized in OLEDs. For example, 4,4'-bis(diphenylphosphine oxide) biphenyl (PO1), synthesized by Sapochak and co-workers, 49 has a triplet exciton energy (2.72 eV) higher than CBP through substitution of the carbazoles with diphenylphosphoryl (Ph 2 P=O) groups; the reason is that the P=O group prevents electronic communication between the central diphenyl core and the outer phenyl groups.…”

Section: Degradation In Host Moleculesmentioning

confidence: 99%

Theoretical investigation of the degradation mechanisms in host and guest molecules used in OLED active layers

2014

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A feature of OLEDs that has to date received little attention is the prediction of the stability of the molecules involved in the electrical and optical processes. Here, we present computational results intended to aid in the development of stable systems. We identify degradation pathways and define new strategies to guide the synthesis of stable materials for OLED applications for both phosphorescent emitters and organic host materials. The chemical reactivity of these molecules in the active layers of the devices is further complicated by the fact that, during operation, they can be either oxidized or reduced (as they localize a hole or an electron) in addition to forming both singlet and triplet excitons.

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Inter-Ligand Energy Transfer and Related Emission Change in the Cyclometalated Heteroleptic Iridium Complex: Facile and Efficient Color Tuning over the Whole Visible Range by the Ancillary Ligand Structure

Cited by 462 publications

References 12 publications

Highly phosphorescent perfect green emitting iridium(iii) complex for application in OLEDs

Highly phosphorescent perfect green emitting iridium(iii) complex for application in OLEDs

Crystal structure of 2-(2-naphthyl)-4,6-dimethylpyrimidine, C16H14N2

Theoretical investigation of the degradation mechanisms in host and guest molecules used in OLED active layers

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