Aggregation Effects on the Emission Spectra and Dynamics of Model Oligomers of MEH-PPV
| Jazyk: | angličtina |
|---|---|
| Rok vydání: | 2009 |
| Předmět: | |
| Zdroj: | The Journal of Physical Chemistry. C: Nanomaterials and Interfaces. 113(43):18851-18862 |
| ISSN: | 1932-7455 1932-7447 |
| DOI: | 10.1021/jp904308h |
| Popis: | The effects of aggregate formation on the photophysical properties of oligomers of MEH-PPV were studied in bulk solution to better understand the effects of aggregation on the emission properties of the polymer. Nanoaggregates of oligomers from 3 to 17 repeat units in length were formed using a solvent reprecipitation method. The spectra are not readily modeled using the classical dipole-dipole coupling picture of interchain interactions. A strong dependence of the photophysics on the oligomer chain length is also observed. Short-chain oligomers produce nanoaggregates with absorption and emission spectra essentially identical to those of the monomer. Long-chain oligomers form aggregates having more strongly perturbed absorption and fluorescence spectra and decreased emission yields. In these aggregates, the size of the 0-0 band relative to that of the vibronic replicates is a sensitive function of aggregate size and solvent precipitation conditions. Their fluorescence lifetimes are also strongly wavelength dependent. These trends are explained in terms of a core-shell model that postulates the existence of "single-chain-like" and "aggregate-like" emitters within a single aggregate. |
| Databáze: | OpenAIRE |
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