Real-Time Investigation of Intercalation and Structure Evolution in Printed Polymer:Fullerene Bulk Heterojunction Thin Films

Thaer Kassar, Nusret S. Güldal, Marvin Berlinghof, Tayebeh Ameri, Andreas Kratzer, Bob C. Schroeder, Giovanni Li Destri, Andreas Hirsch, Martin Heeney, Iain McCulloch, Christoph J. Brabec, Tobias Unruh*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

13 Scopus citations

Abstract

The complex intermixing morphology is critical for the performance of the nanostructured polymer:fullerene bulk heterojunction (BHJ) solar cells. Here, time resolved in situ grazing incidence X-ray diffraction and grazing incidence small angle X-ray scattering are used to track the structure formation of BHJ thin films formed from the donor polymer poly(2,5-bis(3-hexadecylthiophen-2-yl)thieno[3,2-b]thiophene) with different fullerene derivative acceptors. The formation of stable bimolecular crystals through the intercalation of fullerene molecules between the side chains of polymer crystallites is investigated. Such systems exhibit more efficient exciton dissociation but lower photo-conductance and faster decay of charges. On the basis of the experimental observations, intercalation obviously takes place before or with the formation of the crystalline polymer domains. It results in more stable structures whose volume remains constant upon further drying. Three distinct periods of drying are observed and the formation of unidimensional fullerene channels along the π-stacking direction of polymer crystallites is confirmed.

Original languageEnglish (US)
Article number1502025
JournalAdvanced Energy Materials
Volume6
Issue number5
DOIs
StatePublished - Mar 9 2016

Keywords

  • fullerenes
  • grazing incidence diffraction
  • intercalation dynamics
  • organic solar cells
  • thin films

ASJC Scopus subject areas

  • Renewable Energy, Sustainability and the Environment
  • Materials Science(all)

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