Hyperbranched poly(arylene ethynylene)s with triphenylamine core for polymer light‐emitting diodes

Abstract

A series of light-emitting hyperbranched poly(arylene ethynylene)s (HB-PAEs) were prepared by the Sonogashira coupling from bisethynyl of carbazole, fluorene, or dialkoxybenzenes (A 2 type) and tris(4-iodophenyl)amine (B 3 type). For comparison, two linear polymers (L-PAEs) of the HB analogs were also synthesized. The polymers were characterized by Fourier transform infrared, NMR, and GPC. The HB polymers showed excellent solubility in chloroform, THF, and chlorobenzene when compared with their linear analogs. The number-average molecular weight (M n ) of the polymers determined from GPC was found to be in the range of 18,600-34,200. The polymers were thermally stable up to 298-330 C with only 5% weight loss. The absorption maxima of the polymers were between 354 and 411 nm with optical band gap in the range of 2.5-2.9 eV. The HB polymers were found to be highly fluorescent with photoluminescence quantum yields around 33-42%. The highest occupied molecular orbital energy levels of the polymers calculated from onset oxidation potentials were found to be in the range from À5.83 to À6.20 eV. Electroluminescence (EL) properties of three HB-PAEs and one L-PAE were investigated with device configuration ITO/ PEDOT:PSS/Polymer/LiF/Al. The EL maxima of HB-PAEs were found to be in the range of 507-558 nm with turn-on voltages around 7.5-10 V and maximum brightness values of 316-490 cd/m 2 . At the same time, linear analog of one HB-PAE was found to show a maximum brightness of 300 cd/m 2 at a turnon voltage of 8.2 V. V C 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 49: 832-841, 2011

Thiazole-based scaffolding for high performance solar cells

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Pulsed electric field (PEF) as an intensification pretreatment for greener solvent lipid extraction from microalgae

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Synthesis of molecular chains: application of cross-coupling and bromo by iodo exchange reactions

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