Molecular Structure Controlled Transitions between Free-Charge Generation and Trap Formation in a Conjugated Copolymer Series

Bill Pandit, Nicholas E. Jackson, Tianyue Zheng, Thomas J. Fauvell, Eric F. Manley, Meghan Orr, Samantha Brown-Xu, Luping Yu*, Lin X. Chen

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

6 Scopus citations

Abstract

Rational design strategies for controlling the energetics of conjugated "donor-acceptor" copolymers are ubiquitous in the literature, as they allow for simple energy-level tuning strategies to be employed for photovoltaic and transistor applications. Utilizing the recently reported PTRn series of conjugated polymers closely related to the widely implemented material PTB7, we investigate the effect of local copolymer block energetics on the generation of transient excitonic and charge carrier species. It is clearly demonstrated that local copolymer block energetics play a much larger role than is apparent from simple energy-level tuning arguments, and drastically affect the ultrafast generation of free-charge carrier and trap state populations. Specifically, we observe an almost complete reversal in the efficient generation of free-charge in PTB7 to the ultrafast creation of a high percentage of trapped pseudo charge-transfer states. The implications of this secondary effect of "donor-acceptor" energy level tuning are discussed, along with strategies for avoiding the generation of trap states in "donor-acceptor" copolymers.

Original languageEnglish (US)
Pages (from-to)4189-4198
Number of pages10
JournalJournal of Physical Chemistry C
Volume120
Issue number8
DOIs
StatePublished - Mar 3 2016

ASJC Scopus subject areas

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

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