Indacenodithiophene Homopolymers via Direct Arylation: Direct Polycondensation versus Polymer Analogous Reaction Pathways

Abstract

Indacenodithiophene (IDT) based materials are emerging high performance conjugated polymers for use in efficient organic photovoltaics and transistors. However, their preparation generally suffers from long reaction sequences and is often accomplished using disadvantageous Stille couplings. Herein, we present detailed synthesis pathways to IDT homopolymers using C-H activation for all C-C coupling steps. Polyketones are first prepared by direct arylation polycondensation (DAP) in quantitative yield and further cyclized polymer analogously. This protocol is suitable for obtaining structurally well-defined IDT homopolymers, provided that the conditions for cyclization are chosen appropriately and that side reactions are suppressed. Moreover, this polymer analogous pathway gives rise to asymmetric side chain patterns, which allows to fine tune physical properties. Alternatively, IDT homopolymers can be obtained via oxidative direct arylation polycondensation of IDT monomers (oxDAP), leading to IDT homopolymers with similar properties but at reduced yield. Detailed characterization by NMR, IR, UV-vis and PL spectroscopy, and thermal properties, is used to guide synthesis and to explain varying field-effect transistor hole mobilities in the range of 10 -6 -10 -3 cm 2 /Vs.

Temperature-dependent morphology-electron mobility correlations of naphthalene diimide-indacenodithiophene copolymers prepared via direct arylation polymerization

“…Compounds Ph6IDT, NDIBr2 and the model compound Ph8-PIDT were synthesized according to published protocols. 59,60,69 Detailed information about instrumentation and experimental procedures are described in the Electronic Supplementary Information (ESI †). SEC curves of the samples P1-P7 are shown in Figure S5.…”

“…28,[56][57][58] Recently, we reported synthesis of well-defined IDT homo-and copolymers via DAP. 59,60 However, in order to optimize the performance of the material it is essential to understand its structure-property relationships. The influence of MW, end groups, processing solvents and post-temperature treatments are important factors that govern morphology and need to be optimized to understand the performance of new materials for organic electronics.…”

Synthesis of Conjugated Polymers via Transition Metal Catalysed C−H Bond Activation

“…Sommer's group also investigated the hole transport properties of IDT-based polymers prepared by both DArP and ox-DArP, and the best performing polymer showed a hole transport mobility of 10 À 3 cm 2 V À 1 s À 1 . [67] Another work on IDT-based polymers prepared by DArP was reported by Luscombe's group, [68] showing this polymer possesses low stiffness, high ductility, and rapid stress relaxation properties. Another series of thienothiadiazole (TTD) based polymer was reported by Wang's group in 2016 (Scheme 10b).…”

“…Atom force microscopy images also indicate that the morphology of the polymer is homogeneous, but without ordered nanostructures. Sommer's group also investigated the hole transport properties of IDT‐based polymers prepared by both DArP and ox‐DArP, and the best performing polymer showed a hole transport mobility of 10 −3 cm 2 V −1 s −1 [67] . Another work on IDT‐based polymers prepared by DArP was reported by Luscombe's group, [68] showing this polymer possesses low stiffness, high ductility, and rapid stress relaxation properties.…”

Step‐Economical Synthesis of Conjugated Polymer Materials Composed of Three Components: Donor, Acceptor, and π Units

“…Introduction of thiophene units by direct arylation and double cyclization offers a straightforward route for the preparation of IDT derivatives ( Scheme ). [ 47 ] The CH bonds in the IDT derivatives can participate in the polycondensation reaction. [ 48 ]…”