Agnieszka Pron

Easy and versatile synthesis of new poly(thieno[3,4-d]thiazole)s

New alternating copolymers based on thieno[3,4-d]thiazole (TTz) derivatives were synthesized by Stille, Suzuki or direct (hetero)arylation polycondensation (DHAP) reactions using either benzodithiophene (BDT), dithienosilole (DTS), thieno[3,4-c]pyrrole-4,6-dione (TPD), diketopyrrolopyrrole-1,4-dione (DPP) or isoindigo units as comonomers. In particular, the direct hetero(arylation) polycondensation reaction has been shown to be a very interesting tool for a more efficient and economical access to new conjugated polymers. Modifications of the TTz moiety and of the polymer backbone show that it is possible to efficiently modulate the HOMO and LUMO energy levels of TTz-based copolymers. These conjugated polymers exhibit bandgaps between 1.07 and 1.82 eV with HOMO energy levels ranging from −5.06 to −5.48 eV and LUMO energy levels ranging from −3.61 to −4.02 eV.

Direct heteroarylation of β-protected dithienosilole and dithienogermole monomers with thieno[3,4-c]pyrrole-4,6-dione and furo[3,4-c]pyrrole-4,6-dione

Direct C–H bond arylation reactions between heteroarenes and aryl halides provide an atom-economical and “green” alternative to standard cross-coupling reactions (Stille, Suzuki, etc.). Unfortunately, this reaction is not selective and more than one type of C–H bond may react, which, during polymerization reactions, can lead to cross-linked materials. This paper reports the preparation of PDTSiTPD and PDTGeTPD, which have exhibited high efficiencies in organic solar cells, using direct (hetero)arylation polymerization methodologies. In order to circumvent side reactions leading to cross-linked polymers, a number of new dithieno[3,2-b:2′,3′-d]silole (DTSi) monomers were prepared where the β-positions were blocked with alkyl chains and the alkyl groups on the heteroatom were modified. Co-polymers were synthesized with N-alkylthieno[3,4-c]pyrrole-4,6-dione (TPD) and the oxygen congener, N-alkylfuro[3,4-c]pyrrole-4,6-dione (FPD). However, the resulting polymers were not planar, and conjugation of the backbone was disrupted. An efficiency of 1.7% was achieved in bulk heterojunction solar cells (BHJ-SCs).

CHAPTER 19:Direct Arylation/Heteroarylation Polycondensation Reactions

Direct C-H bond arylation reactions between heteroarenes and aryl halides provide an atom economical and “green” alternative to standard crosscoupling reactions (Stille, Suzuki, etc.) and has been used to prepare small molecules and polymers that have application in the field of organic electronics. This chapter will outline the examples from the literature that have used this reaction to prepare homopolymers, such as poly(3-alkylthiophenes), and copolymers that in most cases contain thiophene units. General reaction procedures will be outlined as well as some of the properties of the polymers prepared by this method.