Materials for organic electroluminescence: aluminium vs. boron

Anderson, S.; Weaver, Michael S.; Hudson, A.J.

doi:10.1016/s0379-6779(99)00400-2

Cited by 73 publications

(100 citation statements)

References 9 publications

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“…13,26,[29][30][31] The PL peak emission of 1 is reported at 495-496 nm in CH 2 Cl 2 . 13,21 By comparison, all of the devices listed in Table 1 have shown a red-shift by more than 50 nm. The EL emission from devices A and B is attributed to exciplex formation between 1 and the hole-transporting layer NPB (N,N'-bis(naphthalen-1-yl)-N,N'-bis(phenyl)benzidine).…”

Section: -25mentioning

confidence: 99%

“…The emission from device E at approximately 550 nm has been attributed to Ph 2 BQ, although other origins were also considered. 13 The emission wavelength suggests that the emitting source is more likely AlQ 3 (as in devices C and D), which leaves the EL properties of Ph 2 BQ, as determined from these devices, open to debate. Modifications of the R substituents in R 2 BQ compounds result generally in only small changes in the peak emission wavelength in solution (495-501 nm).…”

Section: -25mentioning

confidence: 99%

“…2,3 It is well documented that light emission in AlQ 3 originates from the quinolinol ligand, from a transition between the lowest unoccupied molecular orbital (LUMO) located on the pyridyl ring and the highest occupied molecular orbital (HOMO) on the phenoxide ring. [4][5][6][7] Understandably, one approach to modify AlQ 3 has been to use substituted 8-hydroxyquinolines (8-HQ), [8][9][10][11][12][13][14][15] or different heterocycles such as 5-hydroxyquinoxaline. 7,16 Alterations of this type have resulted in changes of the peak emission wavelength, but often with a loss in luminous efficiency.…”

Section: Introductionmentioning

confidence: 99%

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The effect of fluorination on the luminescent behaviour of 8-hydroxyquinoline boron compounds

et al. 2008

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A series of boron quinolinate compounds with different degrees of fluorination {Ph 2 BQ 1, (4-F-C 6 H 4 ) 2 BQ 2 and (C 6 F 5 ) 2 BQ 3 (where Q is 8-quinolinoate)} have been However, when the boron compounds 1, 2 or 3 are doped into a (4,4'-bis(carbazol-9-yl)diphenyl (CBP) host, emission solely attributable to 1-3 is observed. In such devices, the boron compounds 1 and 2 outperform AlQ 3 as an emitter at low to moderate current densities.2

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Section: -25mentioning

confidence: 99%

Section: -25mentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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The effect of fluorination on the luminescent behaviour of 8-hydroxyquinoline boron compounds

et al. 2008

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“…When a methyl group is attached to the electron-deficient pyridyl ring it causes a blueshift in the emission (l max increases from 490 to 523 nm for positions 2 to 4, respectively), whereas substitution on the electron-rich phenoxide ring produces a redshift (l max increases from 525 to 568 nm for positions 5 to 7, respectively). [12,[16][17] However, it should be noted that because of steric hindrance, the trisaluminumA C H T U N G T R E N N U N G (iii) complex with 8-hydroxy-2-methylquinoline (the bluest emitter) is not stable, so one of the three quinolinolate ligands must be replaced by a smaller phenolato-type ligand, thus creating the pentacoordinate complexes instead. [1,18] Hence, one cannot be certain whether the dramatic blueshifted emission (l % 490 nm) of the 8-hydroxy-2-methylquinoline complexes is due to methyl-mediated electronic tuning or simply to the less sterically favorable geometry of the 2-methylquinolinolate-aluminumA C H T U N G T R E N N U N G (iii) bonding.…”

Section: Introductionmentioning

confidence: 99%

Effective Manipulation of the Electronic Effects and Its Influence on the Emission of 5‐Substituted Tris(8‐quinolinolate) Aluminum(III) Complexes

Montes

Pohl

Shinar

et al. 2006

Chemistry A European J

172

100

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The unique electron-transport and emissive properties of tris(8-quinolinolate) aluminum(III) (Alq(3)) have resulted in extensive use of this material for small molecular organic light-emitting diode (OLED) fabrication. So far, efforts to prepare stable and easy-to-process red/green/blue (RGB)-emitting Alq(3) derivatives have met with only a limited success. In this paper, we describe how the electronic nature of various substituents, projected via an arylethynyl or aryl spacer to the position of the highest HOMO density (C5), may be used for effective emission tuning to obtain blue-, green-, and red-emitting materials. The synthetic strategy consists of four different pathways for the attachment of electron-donating and electron-withdrawing aryl or arylethynyl substituents to the 5-position of the quinolinolate ring. Successful tuning of the emission color covering the whole visible spectrum (lambda=450-800 nm) was achieved. In addition, the photophysical properties of the luminophores were found to correlate with the Hammett constant of the respective substituents, providing a powerful strategy with which to predict the optical properties of new materials. We also demonstrate that the electronic nature of the substituent affects the emission properties of the resulting complex through effective modification of the HOMO levels of the quinolinolate ligand.

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“…Following the initial report of utilization of mer-Alq3 as electron transport material and emitting layer in OLED [21,22], the derivatives of metal quinolates has become the focus of new electroluminescent materials research with mer-Alq3 being the most often used [8,23,24]. Although research into the development of OLEDs in the past decade is rapidly growing, in recent years the studies of the fundamental molecular properties of metaloquinolates have been reported in the literature [25][26][27][28][29][30][31][32][33][34][35][36][37][38][39]. It is clear from these reports that a detailed understanding of the relationship between the ligand structure and optical properties of the resulting Al-complex is essential to make progress in the improvement of OLED devices.…”

Section: Introductionmentioning

confidence: 99%

Push-pull effect on the geometrical, optical and charge transfer properties of disubstituted derivatives of mer-tris(4-hydroxy-1,5-naphthyridinato) aluminum (mer-AlND3)

Rao

Bhanuprakash

2016

Open Chemistry

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Push-pull effect on the geometrical, optical and charge transfer properties of disubstituted derivatives of mer-tris(4-hydroxy-1,5-naphthyridinato) aluminum (mer-AlND3) DOI: 10.1515/chem-2016-0001 received April 23, 2015 accepted November 14, 2015. Abstract: To design innovative and novel optical materials with high mobility, two kinds of disubstituted derivatives for mer-tris(4-hydroxy-1,5-naphthyridinato) aluminum (mer-AlND3) with push (EDG)-pull (EWG) substituents have been designed. The structures of mer-tris(8-EDG-2-EWG-4-hydroxy-1,5-naphthyridinato) aluminum (type I) and mer-tris(8-EWG-2-EDG-4-hydroxy-1,5-naphthyridinato) aluminum (type II) in the ground and first excited states have been optimized at the B3LYP/6-31G(D) and CIS/6-31G(D) level of theory, respectively. It can be seen from frontier molecular orbitals analysis, in all these complexes, the highest occupied molecular orbital (HOMO) is localized on the pyridine-4-ol ring of A-ligand while lowest unoccupied molecular orbital (LUMO) is on the pyridyl ring of B-ligand in ground state irrespective of electron donor/acceptor substitution present on the ligands similar to that of mer-tris(8-hydroxyquinoline) aluminum (mer-Alq3) and parent mer-AlND3.The absorption and emission wavelengths have been evaluated at the TD-PBE0/6-31G(D) level and it can be see that all the type I derivatives show blue shift while most of the type II derivatives show red shift compared to mer-AlND3. All the disubstituted complexes have showed hypsochromic shifts in both the absorption and emission spectra when compared with the calculated absorption and emission spectra respectively of mer-Alq3. It can be seen that the reorganization energies of some of the disubstituted derivatives are comparable with merAlq3 and these derivatives might be good candidates for emitting materials in OLED.

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Materials for organic electroluminescence: aluminium vs. boron

Cited by 73 publications

References 9 publications

The effect of fluorination on the luminescent behaviour of 8-hydroxyquinoline boron compounds

The effect of fluorination on the luminescent behaviour of 8-hydroxyquinoline boron compounds

Effective Manipulation of the Electronic Effects and Its Influence on the Emission of 5‐Substituted Tris(8‐quinolinolate) Aluminum(III) Complexes

Push-pull effect on the geometrical, optical and charge transfer properties of disubstituted derivatives of mer-tris(4-hydroxy-1,5-naphthyridinato) aluminum (mer-AlND3)

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