Semiconducting alternating multi-block copolymers: Via a di-functionalized macromonomer approach

The development of fully-conjugated semiconducting block-copolymers is an important goal for organic electronics, but to date has been almost exclusively limited to materials containing poly(3-alkylthiophenes). Here we present the prototype of a class of fully-conjugated semiconducting block copolymers (prepared using a versatile route based on conjugated macromonomers and a cross-coupling polycondensation) that exhibit hole mobility in field effect transistors of the order of 0.1 cm 2 V −1 s −1 and nano-scopic phase domain separation. Controlling the self-assembly of π-conjugated polymers is a key parameter for improving the performance of solution-processed semiconducting devices based on organic materials. 1–3 Fully-conjugated block copolymers have recently emerged as promising materials that combine suitable semiconducting properties with the capability to controllably self-assemble at the nanoscale. 4 Indeed, the potential ability to change the chemical nature and size of the blocks in a nanophase-separated copolymer is expected to surmount many of the current challenges in morphology and interfacial structure control for polymer-based electronic devices. For example, in organic photovoltaics (OPVs), which require a nanoscale bulk heterojunction (BHJ) comprised of electron donor and electron acceptor domains, block copolymers offer a route to size-tuneable, thermodynamically stable phase domains. 5 Moreover, as block copolymers allow for the incorporation of both electron and hole transporting moieties in a single solu-tion processing step, the fabrication of organic light emitting diodes 6 and OPV devices can be simplified.