Phase separation and molecular intermixing in polymer-fullerene bulk heterojunction thin films

Matthias A. Ruderer, Robert Meier, Lionel Porcar, Robert Cubitt, Peter Müller-Buschbaum

Research output: Contribution to journalArticlepeer-review

72 Scopus citations

Abstract

The phase separation and molecular intermixing in poly(3-hexylthiophene) (P3HT)/[6,6]-phenyl-C61 butyric acid methyl ester (PCBM) bulk heterojunction thin films are investigated as a function of the overall PCBM content. The structural length scales, phase sizes, and molecular miscibility ratio in bulk heterojunction films are probed with grazing incidence small-angle neutron scattering (GISANS). The PCBM content is varied between 9 and 67 wt %. For the symmetric P3HT/PCBM ratio, which is typically highly efficient in photovoltaic devices, a structure size of 20 nm, the largest PCBM phases, and 18 vol % dispersed PCBM in the amorphous P3HT phase are found. The molecularly dispersed PCBM content is found to increase with the overall PCBM content. Absorption measurements complement the GISANS investigation.

Original languageEnglish
Pages (from-to)683-688
Number of pages6
JournalJournal of Physical Chemistry Letters
Volume3
Issue number6
DOIs
StatePublished - 15 Mar 2012

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