Synthesis and physical properties of poly(aryl ether phthalazine)s

Singh, Rina; Hay, Allan S.

doi:10.1021/ma00029a003

Cited by 48 publications

(44 citation statements)

References 3 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…In the first step, trans-1,2-dibenzoylethylene transformed thermally into its cis intermediate isomer, [19] which further reacted with hydrazine to yield 3,6-bis(phenyl)pyridazine (BPPya) through an intramolecular ring-closure reaction. Ir(BPPya) 3 was obtained by refluxing the above ligand and tris(acetylacetonato)-iridium(III) in degassed glycerol.…”

mentioning

confidence: 99%

High Efficiency and Small Roll‐Off Electrophosphorescence from a New Iridium Complex with Well‐Matched Energy Levels

et al. 2008

View full text Add to dashboard Cite

It is well-known that, under electrical excitation, singlet and triplet excitons will be formed in organic light-emitting diodes (OLEDs) in the ratio of approximately 1 to 3 in the organic layers, where recombination of opposite charges occurs. The harvesting of triplet excitons for emission (termed as phosphorescence) cannot be obtained in common organic compounds because of the spin-forbidden rule. Thus, metal complexes, possessing the spin-orbit coupling effect caused by the heavy metal, are commonly used as phosphorescent emitters. Hence, intensive efforts have been made towards the development of metal complexes with different colors.[ [9] and 11 % (or 11.2 lm W -1 ) for red [3] have been reported in the literature. On the other hand, PhOLEDs, in spite of having the ability of harvesting triplet energy that can result in high efficiency, are usually characterized by high rolloff in efficiency with increasing current density.[2,9-11] Typically, the external quantum efficiency (EQE) declines sharply at current densities above 20 mA cm -2 , which is the practical driving condition for passive-matrix OLEDs (PMOLEDs). Furthermore, high driving voltages are usually observed in these devices, which can result in low power efficiencies. [12,13] As with the issues of generally high roll-off and driving voltage in PhOLEDs, it has been found that the roll-off was attributed to the triplet-triplet (T-T) annihilation [14,15] and/or the field-induced exciton dissociation [16,17] when there was a high density of triplet excitons with long lifetimes. The high driving voltage is supposed to be caused by two factors: one is the deep and strong charge traps caused by the doped iridium complex in the emitting layer; [12,13] the second is related to the highest occupied molecular orbital (HOMO), which transfers holes, and the lowest unoccupied molecular orbital (LUMO), which transfers electrons, of materials used. In PhOLEDs, to match the triplet energy level of the dopant for exothermic energy transfer, high bandgap host materials are usually required. So the difference in HOMO levels and/or LUMO levels between the carrier transporting and the emitting layers is usually large, making charge injection into the emitting layer energetically unfavorable and thus leading to high driving voltage.[18]To achieve high efficiency PhOLEDs with the characteristics of small roll-off and low driving voltage, it is believed that both high-efficiency phosphorescent materials and the practical construction of devices are needed. Of primary importance in device architectures is that the hole/electron injection barrier from the hole/electron transport layer to the emitting layer should be small, which will favor charge injection and avoid high driving voltage. Secondly, the density of triplet excitons should be low enough for the purpose of minimizing T-T exciton annealing. This criterion can be achieved by evenly distributing excitons in the bulk emission layer rather than having excitons located only at the narrow interface sites. Finally, the...

show abstract

mentioning

confidence: 99%

High Efficiency and Small Roll‐Off Electrophosphorescence from a New Iridium Complex with Well‐Matched Energy Levels

et al. 2008

View full text Add to dashboard Cite

show abstract

“…Both the poly-(isoquinoline)s and poly(phthalazine)s, which were also obtained from the conversion of the diketone polymers, have higher T g 's than their diketone precursors. However, the poly(isoquinoline)s have lower T g 's than the corresponding poly(phthalazine)s, which may be due to the pendent phenyl group in poly(isoquinoline)s. 11,12 In the present case, the extra pendent methyl group in poly(isoindole)s may be responsible for the further lowering of the T g 's of the poly(isoindole)s. Thermal stabilities of poly(isoindole)s also decreased as suggested from TGA measurements. However, the 5% weight loss temperatures of poly(isoindole)s synthesized here are still in the range of 457-511°C, indicating that they are thermostable polymers.…”

Section: Isoindole-containing Polymersmentioning

confidence: 64%

“…The use of a polymer precursor to prepare heterocycliccontaining polymers has been extensively used in this laboratory as well as others. For example, poly(phthalazine)s, 11 poly(isoquinoline)s, 12 and poly(2,5-pyrrole) 13 have been synthesized from their respective diketone precursor polymers. We selected p-toluidine as the reactant for the synthesis of a series of isoindole-containing polymers.…”

Section: Isoindole-containing Polymersmentioning

confidence: 99%

Synthesis of highly fluorescent materials: Isoindole-containing polymers

Ding

Hay

1999

J. Polym. Sci. A Polym. Chem.

Self Cite

View full text Add to dashboard Cite

A series of stable, highly fluorescent and highly phenylated isoindoles have been synthesized by treating the respective o‐dibenzoylbenzenes with anilines at 200°C in the presence of a catalytic amount of p‐toluenesulfonic acid. The correlation between the emission frequences and the structures of the isoindoles is described. The same reaction has also been used to transform a series of poly(o‐dibenzoylbenzene)s into poly(isoindole)s. The resulting polymers have been studied by 1H‐NMR, DSC, TGA, and fluorescence spectra. They are highly fluorescent materials with high molecular weights, high glass transition temperatures, and high thermal stabilities. The tetraphenyl substituted isoindole‐containing polymers have a maximum emission around 468 nm, whereas the diphenyl substituted isoindole‐containing polymers have their maximum emission around 486 nm. © 1999 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 37: 3293–3299, 1999

show abstract

“…2 ) . 3 The physical and mechanical properties of polymers 8a-f and 9a-e appear in Table 11. (Table 111) shows that ring closure of the polymers to poly(ary1 ether phthalazine ) s has resulted in a dramatic change in the physical properties.…”

Section: Resultsmentioning

confidence: 99%

“…Phthalazine has been polymerized in an oxidative electrochemical polymerization to give high molecular weight poly(phtha1azine) in an attempt to prepare a conducting organic p01ymer.~ Amorphous poly( aryl ether phtha1azine)s have been reported by Singh and Hay. 3 The phthalazine polymers were prepared following two different procedures. Poly(ary1 ether ketone)s containing an ortho-diketone moiety were reacted with an excess of hydrazine monohydrate to give poly(ary1 ether phtha1azine)s and these polymers were also prepared from fluorinated monomers, which used the phthalazine moiety as an activating group, by nucleophilic displacement polymerization with commercial bisphenols.…”

Section: Introductionmentioning

confidence: 99%