Influence of molecular shape on solid-state packing in disordered PC61BM and PC71BM fullerenes

Monika Williams, Naga Rajesh Tummala, Saadullah G. Aziz, Chad Risko, Jean Luc Brédas

Research output: Contribution to journalArticlepeer-review

43 Scopus citations


Molecular and polymer packings in pure and mixed domains and at interfacial regions play an important role in the photoconversion processes occurring within bulk heterojunction organic solar cells (OSCs). Here, molecular dynamics simulations are used to investigate molecular packing in disordered (amorphous) phenyl-C70-butyric acid-methyl ester (PC71BM) and its C60 analogue (PC61BM), the two most widely used molecular-based electron-accepting materials in OSCs. The more ellipsoidal character of PC71BM leads to different molecular packings and phase transitions when compared to the more spherical PC61BM. Though electronic structure calculations indicate that the average intermolecular electronic couplings are comparable for the two systems, the electronic couplings as a function of orientation reveal important variations. Overall, this work highlights a series of intrinsic differences between PC71BM and PC61BM that should be considered for a detailed interpretation and modeling of the photoconversion process in OSCs where these materials are used.

Original languageEnglish
Pages (from-to)3427-3433
Number of pages7
JournalJournal of Physical Chemistry Letters
Issue number19
StatePublished - Oct 2 2014

Bibliographical note

Publisher Copyright:
© 2014 American Chemical Society.


  • amorphous solids
  • intermolecular electronic couplings
  • organic solar cells
  • substituted fullerenes

ASJC Scopus subject areas

  • General Materials Science
  • Physical and Theoretical Chemistry


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