How chromophore shape determines the spectroscopy of phenylene-vinylenes: Origin of spectral broadening in the absence of aggregation

K. Becker, E. Da Como, J. Feldmann, F. Scheliga, E. Thorn Csányi, S. Tretiak, J. M. Lupton

Research output: Contribution to journalArticlepeer-review

89 Citations (Scopus)

Abstract

Single oligo(phenylene-vinylene) molecules constitute model systems of chromophores in disordered conjugated polymers and can elucidate how the actual conformation of an individual chromophore, rather than that of an overall polymer chain, controls its photophysics. Single oligomers and polymer chains display the same range of spectral properties. Even heptamers support π-electron conjugation across ∼80° curvature, as revealed by the polarization anisotropy in excitation and supported by quantum chemical calculations. As the chain becomes more deformed, the spectral linewidth at low temperatures, often interpreted as a sign of aggregation, increases up to 30-fold due to a reduction in photophysical stability of the molecule and an increase in random spectral fluctuations. The conclusions aid the interpretation of results from single-chain Stark spectroscopy in which large static dipoles were only observed in the case of narrow transition lines. These narrow transitions originate from extended chromophores in which the dipoles induced by backbone substituents do not cancel out. Chromophores in conjugated polymers are often thought of as individual linear transition dipoles, the sum of which make up the polymer's optical properties. Our results demonstrate that, at least for phenylene-vinylenes, it is the actual shape of the individual chromophore rather than the overall chromophoric arrangement and form of the polymer chain that dominates the spectroscopic properties.

Original languageEnglish
Pages (from-to)4859-4864
Number of pages6
JournalJournal of Physical Chemistry B
Volume112
Issue number16
DOIs
Publication statusPublished - 24 Apr 2008
Externally publishedYes

Fingerprint

Dive into the research topics of 'How chromophore shape determines the spectroscopy of phenylene-vinylenes: Origin of spectral broadening in the absence of aggregation'. Together they form a unique fingerprint.

Cite this