Side-Chain Influence on the Mass Density and Refractive Index of Polyfluorenes and Star-Shaped Oligofluorene Truxenes

Paulina O. Morawska, Yue Wang, Arvydas Ruseckas, Clara Orofino-Penia, Alexander L. Kanibolotsky, Ramkumar Santhanagopal, Nils Fröhlich, Martin Fritsch, Sybille Allard, Ullrich Scherf, Peter J. Skabara, Ifor D.W. Samuel, Graham A. Turnbull*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

Abstract

The density of organic semiconductor films is an important quantity because it is related to intermolecular spacing which in turn determines the electronic and photophysical properties. We report thin film density and refractive index measurements of polyfluorenes and star-shaped oligofluorene truxene molecules. An ellipsometer and a procedure using a spectrophotometer were used to determine film thickness and mass of spin-coated films, respectively. We present a study of the effect of alkyl side-chain length on the volumetric mass density and refractive index of the materials studied. The density measured for poly(9,9-di-n-octylfluorene) (PF8) was 0.88 ± 0.04 g/cm3 and decreased with longer alkyl side chains. For the truxene molecule with butyl side chains (T3 butyl), we measured a density of 0.90 ± 0.04 g/cm3, which also decreased with increasing side-chain length.

Original languageEnglish
Pages (from-to)22102-22107
Number of pages6
JournalJournal of Physical Chemistry C
Volume119
Issue number38
DOIs
Publication statusPublished - 24 Sept 2015

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