title: Defect-free Naphthalene Diimide Bithiophene Copolymers with Controlled Molar Mass and High Performance via Direct Arylation Polycondensation.
abstract: A highly efficient, simple, and environmentally friendly protocol for the synthesis of an alternating naphthalene diimide bithiophene copolymer (PNDIT2) via direct arylation polycondensation (DAP) is presented. High molecular weight (MW) PNDIT2 can be obtained in quantitative yield using aromatic solvents. Most critical is the suppression of two major termination reactions of NDIBr end groups: nucleophilic substitution and solvent end-capping by aromatic solvents via C-H activation. In situ solvent end-capping can be used to control MW by varying monomer concentration, whereby end-capping is efficient and MW is low for low concentration and vice versa. Reducing C-H reactivity of the solvent at optimized conditions further increases MW. Chain perfection of PNDIT2 is demonstrated in detail by NMR spectroscopy, which reveals PNDIT2 chains to be fully linear and alternating. This is further confirmed by investigating the optical and thermal properties as a function of MW, which saturate at Mn ≈ 20 kDa, in agreement with controls made by Stille coupling. Field-effect transistor (FET) electron mobilities μsat up to 3 cm(2)/(V·s) are measured using off-center spin-coating, with FET devices made from DAP PNDIT2 exhibiting better reproducibility compared to Stille controls.
authors.affiliation: †Makromolekulare Chemie, Universität Freiburg, Stefan-Meier-Straße 31, 79104 Freiburg, Germany.|‡Freiburger Materialforschungszentrum, Stefan-Meier-Straße 21, Universität Freiburg, 79104 Freiburg, Germany.
authors.forename: Rukiya
authors.initials: R
authors.lastname: Matsidik
authors.affiliation: §Leibniz Institut für Polymerforschung Dresden e.V., Hohe Straße 6, 01069 Dresden, Germany.
authors.forename: Hartmut
authors.initials: H
authors.lastname: Komber
authors.affiliation: ∥Center for Nanoscience and Technology @PoliMi, Instituto Italiano di Tecnologia, Via Pascoli 70/3, 20133 Milano, Italy.
authors.forename: Alessandro
authors.initials: A
authors.lastname: Luzio
authors.affiliation: ∥Center for Nanoscience and Technology @PoliMi, Instituto Italiano di Tecnologia, Via Pascoli 70/3, 20133 Milano, Italy.
authors.forename: Mario
authors.initials: M
authors.lastname: Caironi
authors.affiliation: †Makromolekulare Chemie, Universität Freiburg, Stefan-Meier-Straße 31, 79104 Freiburg, Germany.|‡Freiburger Materialforschungszentrum, Stefan-Meier-Straße 21, Universität Freiburg, 79104 Freiburg, Germany.
authors.forename: Michael
authors.initials: M
authors.lastname: Sommer