Tin-Free Direct C-H Arylation Polymerization for High Photovoltaic Efficiency Conjugated Copolymers

Alexander S. Dudnik, Thomas J. Aldrich, Nicholas D. Eastham, Robert P. H. Chang, Antonio Facchetti, Tobin J Marks

Research output: Contribution to journalArticle

73 Citations (Scopus)

Abstract

A new and highly regioselective direct C-H arylation polymerization (DARP) methodology enables the reproducible and sustainable synthesis of high-performance π-conjugated photovoltaic copolymers. Unlike traditional Stille polycondensation methods for producing photovoltaic copolymers, this DARP protocol eliminates the need for environmentally harmful, toxic organotin compounds. This DARP protocol employs low loadings of commercially available catalyst components, Pd2(dba)3·CHCl3 (0.5 mol%) and P(2-MeOPh)3 (2 mol%), sterically tuned carboxylic acid additives, and an environmentally friendly solvent, 2-methyltetrahydrofuran. Using this DARP protocol, several representative copolymers are synthesized in excellent yields and high molecular masses. The DARP-derived copolymers are benchmarked versus Stille-derived counterparts by close comparison of optical, NMR spectroscopic, and electrochemical properties, all of which indicate great chemical similarity and no significant detectable structural defects in the DARP copolymers. The DARP- and Stille-derived copolymer and fullerene blend microstructural properties and morphologies are characterized with AFM, TEM, and XRD and are found to be virtually indistinguishable. Likewise, the charge generation, recombination, and transport characteristics of the fullerene blend films are found to be identical. For the first time, polymer solar cells fabricated using DARP-derived copolymers exhibit solar cell performances rivalling or exceeding those achieved with Stille-derived materials. For the DARP copolymer PBDTT-FTTE, the power conversion efficiency of 8.4% is a record for a DARP copolymer.

Original languageEnglish
Pages (from-to)15699-15709
Number of pages11
JournalJournal of the American Chemical Society
Volume138
Issue number48
DOIs
Publication statusPublished - Dec 7 2016

    Fingerprint

ASJC Scopus subject areas

  • Catalysis
  • Chemistry(all)
  • Biochemistry
  • Colloid and Surface Chemistry

Cite this