Alternating conjugated polymers of ethylenedioxythiophene and fluorene are prepared using three different synthetic methods to investigate the effects of these synthetic methods on the purity, field‐effect transistor (FET) performance, and organic photovoltaic (OPV) performance of the polymer. In this study, microwave‐assisted direct arylation polycondensation is used to obtain a high‐purity, high‐molecular‐weight (147 kDa) polymer. This pure polymer exhibits a high FET hole mobility of 1.2 × 10−3 cm2 V−1 s−1 and high OPV performance with a power conversion efficiency of 4%, even though the polymer forms an amorphous film, which absorbs in a limited region of the spectrum.

Direct arylation polycondensation reactions using a simple catalytic system gave eight kinds of bithiophene-based alternating copolymers. The conditions for the reactions of 3,3′,4,4′-tetramethylbithiophene with dibromoarylenes were optimized to obtain high-molecular-weight polymers without formation of cross-linked structures. In the reaction of a dibromoarylene containing a reactive C-H bond, a short reaction 2 time (1.5 h) was suitable for preventing side reactions. In contrast, a long reaction time (6 h) gave high-molecular-weight polymers from dibromoarylene monomers without a reactive C-H bond. This polycondensation reaction enables the synthesis of polymers containing dye structures such as diketopyrrolopyrrole and isoindigo, which are applicable as materials for polymer solar cells.

For synthesis of π-conjugated polymers, polycondensation via direct arylation reactions of C−H bonds in aromatic monomers with dibromo-arylenes has attracted increasing attention as a simple synthetic method in which the preparation of organometallic reagents is unnecessary. To develop direct arylation polycondensation for practical use in the synthesis of optoelectronic polymer materials, microwave-assisted reactions were investigated and optimized in terms of a kind of base, concentration, reaction time, and amount of catalyst. Under the optimized conditions, the microwave-assisted direct arylation of 3,4-ethylenedioxythiophene with dibromofluorene for 30 min with catalyst (1 mol %) gave the corresponding polymer with an extremely high molecular weight up to 147 000. The high molecular weight of the polymer enables formation of a large and flexible self-standing film, leading to an advantage in fabricating organic thin-film devices. The elemental analysis and MALDI-TOF-MS reveal that the polymer has high purity and no bromo-and metallo-terminals. Because only microwave-assisted direct arylation provided these features in the polymer, the present method is superior to conventional methods. Therefore, microwave-assisted polycondensation via direct arylation methodology lends itself well to practical application using inherent product from economical and environmental points of view for the synthesis of pure optoelectronic materials.

A simple and efficient process for synthesizing tetraalkoxysilanes from silica and alcohols was developed using molecular sieves as dehydrating agents.