Photophysical process of MEH-PPV solution

Zheng, Min; Bai, Fenglian; Zhu, Daoben

doi:10.1016/s1010-6030(98)00285-8

Cited by 70 publications

(55 citation statements)

References 8 publications

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“…Differently, toluene and other aromatic solvents undergo preferential interaction with the conjugated polymer backbone (vinylene-phenylene groups), which adopt more planar conformations. 7,9,10,14,[21][22][23]26,28,32,43,44 One unequivocal experimental demonstration of the preferential solvation of the lateral groups by non-aromatic solvents was the orientation of these groups perpendicular to the macromolecular back-bone making the film surface more polar whereas the coplanar orientation were observed when the film was spun using aromatic solvents. 9 Consequently, greater constraints are imposed on the backbone that limit the possible number of conformations.…”

Section: Photoluminescence In Dilute Solutionsmentioning

confidence: 99%

“…[24][25][26][27][28] The role of the solvent depends on its solvation power as a whole, as well as on its selectivity: it has been shown that some solvents, like THF and chloroform, have a preference for MEH-PPV ramifications, while others, like chlorobenzene, xylene and toluene, mainly solvate the polymer backbone, resulting in different macromolecular conformations. 8,[29][30][31][32] This way, the distribution of the effective conjugation length and, consequently, the emission profile are changed.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Solvent and molecular weight effects on fluorescence emission of MEH-PPV

Cossiello¹,

Akcelrud²,

Atvars³

2005

J. Braz. Chem. Soc.

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Nesse trabalho se estudou sistematicamente o efeito de dois bons solventes sobre os espectros de excitação e de fluorescência em condições fotoestacionárias do MEH-PPV com três massas molares diferentes, -M n = 51 kg mol ) e em filmes produzidos por espalhamento de soluções, mostrando diferenças que decorrem da diferente forma de solvatação das cadeias pelos diferentes solventes. Um deslocamento espectral para o vermelho foi observado em concentrações mais altas 10 -6 mol L -1 e pode ser explicado pela regra de Kasha para uma orientação anti-paralela dos momentos de transição dos dois cromóforos. As conformações em solução são parcialmente mantidas no estado sólido alem do fato de que os espectros se deslocam para o vermelho e são atribuídos à formação de agregados. Recozimento dos filmes em temperaturas acima da transição vítrea elimina as conformações mais tensionadas das cadeias, apaga o efeito de memória e leva a espectros de fluorescência mais finos.Here we systematically studied the excitation and the fluorescence steady-state spectroscopy of poly(2-methoxy-5(2'-ethylhexyloxy)-1,4-phenylenevinylene) (MEH-PPV) with three molecular weights, -M n = 51 kg mol -1 , -M n = 86 kg mol -1 and -M n = 125 kg mol -1 , in two equally good solvents and several concentrations, from dilute solutions to solid-state films produced by casting. The appropriateness of the two solvents was established by comparing their solubility parameters and the solubility parameter of the MEH-PPV estimated using the Small, the Van Krevelen and the Hoy models. Thus, chloroform and toluene were chosen. Fluorescence spectra were recorded for solutions in several concentrations (10 -8 mol L -1 to 10 -4 mol L -1 ) and films produced by casting, showing that chloroform and toluene solvate the polymer chain differently. Diluted solutions (10 -8 mol L -1 ) in chloroform exhibit broader fluorescence spectra. A red-shift of the fluorescence spectra was observed for concentrations higher than 10 -6 mol L -1 that can be explained using Kasha's rule for the sandwich anti-parallel orientation of the transition moments of the two chromophores. The conformations observed in solutions are partially retained in the solid films in addition to the broader red-shift spectra attributed to aggregated forms of the macromolecular segments. Annealing of the polymer films at the glass transition temperature eliminates the more stressed conformations, erases the memory and leads to sharper fluorescence spectra.

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Section: Photoluminescence In Dilute Solutionsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Solvent and molecular weight effects on fluorescence emission of MEH-PPV

Cossiello¹,

Akcelrud²,

Atvars³

2005

J. Braz. Chem. Soc.

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“…The emission peak at short wavelength can be attributed to an excitonic state whereas the shoulder at long wavelength, from aggregates formed between subunits of polymer chains of the excimeric state. 15 PL maxima of copolymers (a, b, and c) showed blue shifts compared to those of conventional PPVs. This can be explained that the introduction of a carbazole moiety in the backbone led to hypsochromic shift in PL emission due to increase in the bandgap.…”

Section: Resultsmentioning

confidence: 90%

Preparation and Photoluminescence Characteristics of Carbazole-Poly(p-phenylenevinylene)s

Lee

Suh

et al. 2002

Polym J

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“…MEH-PPV are predominately p type, under certain circumstances can be n-type [14], and the highly conductive I-MWNT are p-type due to doping process with Iodine [15]. This suggests that the nanotubes may introduce holes to the polymer by a mechanism such as charge transfer.…”

Section: A Electrical Propertiesmentioning

confidence: 99%

Conductivity enhancement of nanocomposited MEH-PPV:I-MWNT thin film

Sarah

Zahid

Noor

et al. 2012

2012 IEEE Symposium on Humanities, Science and Engineering Research

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In this paper, we report the electrical conductivity of nanocomposited MEH-PPV:I-MWNT thin film by varying the composition of Iodine doped multi-walled nanotubes (I-MWNT) in MEH-PPV matrix from 0, 2 and 4 wt%. Electrical conductivity showed increasing in value as the composition of I-MWNT increased from 0, 2 to 4 wt%. The value of conductivity is very outstanding when the polymer was blended with I-MWNT where the value rise from pure MEH-PPV, 81.6 x 10 -4 S/m to 67.68 x 10 4 and 80.28 x 10 4 S/m for 2 and 4 wt% respectively. The surface morphology was investigated using atomic for microscopy (AFM). Roughness of the thin film showed decrement in value from 5.385 nm, 0.751 nm and 0.643 nm for 0, 2, and 4 wt% respectively. Meanwhile, the absorbance value increase slightly from about 0.16 (0 wt%) to about 0.165 and 0.17 ( 2 and 4 wt% respectively). The low absorbance shows that low photon is absorbed and therefore, there is no current changes when the sample is illuminated compared to in dark.

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Photophysical process of MEH-PPV solution

Cited by 70 publications

References 8 publications

Solvent and molecular weight effects on fluorescence emission of MEH-PPV

Solvent and molecular weight effects on fluorescence emission of MEH-PPV

Preparation and Photoluminescence Characteristics of Carbazole-Poly(p-phenylenevinylene)s

Conductivity enhancement of nanocomposited MEH-PPV:I-MWNT thin film

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