Precise synthesis of well-defined electron conducting and donor-acceptor semiconducting copolymers for organic electronics

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This project aims at development of chain growth catalyst transfer polycondensation method for preparation of well defined electron deficient semiconducting polymers for their applications in organic electronic devices (e.g., solar cells and field effect transistors). Currently dominating step growth methods for preparation of semiconducting polymers do not allow a straightforward control over molecular weight, polydispersity, end groups and polymer architectures, factors which greatly influence thin film morphology and molecular orientation. These, in turn, are factors which define (frequently limit) performance of optoelectronic devices. Catalyst transfer polycondensations (CTPs) nowadays maturate as unique tool for the synthesis of well defined polymers and block copolymers. However, range of monomers which can be polymerized by CTP methods are mostly limited to simple, yet electron rich monomers. These are not favorable since the best performing semiconducting polymers are usually built of donor (D) and acceptor (A) units, the polymerization of which is, largely underdeveloped. Recently, the Kiriy group developed method to controllably polymerize such D/A monomer and this project aims at further development of this success. Particularly, in this project we aim at synthesis of 1) donor acceptor homopolymers with specific starting and end groups able to drive self assembly and interfacial properties of the polymers (such as to covalently bind to metal electrodes) and 2) al conjugated block copolymers in which at least one block is a DA copolymer. At the first stage, the project aims at optimization of the chain growth synthesis of one of the best n type polymer P(NDI2ODT2)) (also known as N2200) by varying nature of ligands in Ni and Pd initiators as well as optimization of polymerization conditions to avoid chain termination. This task will be realized through detailed mechanistic investigations. With the optimal initiator in hands, at the second stage, we will prepare polymers with specific start/end groups, such as pyridyl, to provide binding of polymer chains to metal electrodes and facilitate charge injection process. Self assembly (binding to electrodes, morphology) and optoelectronic properties of obtained block copolymers will be also investigated. Finally, most promising samples will be selected and delivered to collaborators for further utilization in optoelectronic devices.