Molecular Rectification in Conjugated Block Copolymer Photovoltaics

Christopher Grieco, Melissa P. Aplan, Adam Rimshaw, Youngmin Lee, Thinh P. Le, Wenlin Zhang, Qing Wang, Scott T. Milner, Enrique D. Gomez, John B. Asbury

Research output: Contribution to journalArticlepeer-review

27 Scopus citations

Abstract

We investigate the influence that covalent linkage of electron donating and accepting blocks in high performance fully conjugated block copolymer photovoltaics has on charge generation and recombination using ultrafast mid-infrared transient absorption spectroscopy. We show that block copolymer architectures containing a conjugated bridge between the donor and acceptor groups can be used to form ordered mesoscale morphologies that lead to improved photovoltaic performance without enhancing charge recombination. Judicious placement of an electron-rich moiety in the electron accepting block of the block copolymer creates a donor-bridge-acceptor architecture that slows intramolecular charge transfer across the covalent linkage. Charge recombination in such donor-bridge-acceptor block copolymer films proceeds at the same rate as it does in their corresponding homopolymer blends for which the donor and acceptor blocks are not covalently linked, indicating that recombination is dominated by intermolecular charge transfer in both systems. The electrical and morphological properties of functional block copolymer photovoltaics are correlated with their underlying charge generation and recombination kinetics, permitting us to identify key design rules for further improvements in the power conversion efficiency of fully conjugated block copolymer solar cells.

Original languageEnglish (US)
Pages (from-to)6978-6988
Number of pages11
JournalJournal of Physical Chemistry C
Volume120
Issue number13
DOIs
StatePublished - Apr 21 2016

All Science Journal Classification (ASJC) codes

  • Electronic, Optical and Magnetic Materials
  • Energy(all)
  • Physical and Theoretical Chemistry
  • Surfaces, Coatings and Films

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