Abstract
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. Shortchain 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.
| Original language | English |
|---|---|
| Pages (from-to) | 18851-18862 |
| Number of pages | 12 |
| Journal | Journal of Physical Chemistry C |
| Volume | 113 |
| Issue number | 43 |
| DOIs | |
| State | Published - 2009 |
ASJC Scopus subject areas
- Electronic, Optical and Magnetic Materials
- General Energy
- Physical and Theoretical Chemistry
- Surfaces, Coatings and Films