Indacenodithiophene homopolymers via direct arylation: direct polycondensation versus polymer analogous reaction pathways

TL;DR

This paper introduces efficient synthesis methods for indacenodithiophene (IDT) homopolymers using direct arylation, enabling better control over structure and properties for organic electronics.

Contribution

It presents a new direct arylation polycondensation approach for IDT polymers, improving synthesis efficiency and structural control compared to traditional methods.

Findings

High-yield synthesis of IDT homopolymers via DAP

Ability to tune physical properties through side chain patterns

Field-effect mobilities range from 10^-6 to 10^-3 cm^2/Vs

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 cm2/Vs.