Conjugated polymers are able to conduct electricity because they are a chain of conjugated molecules where electrons can move freely due to their overlapping electron p-orbitals. Effectively, they are excellent molecular wires. Moreover, they are akin to semiconductor materials (they have energy gaps), so they can be used for electronic (plastic electronics) and photovoltaic (organic solar cells) applications.
The electrical conductivity, Seebeck coefficient, and power factor of CP3–Na were estimated as 9.1 × 10−3 S cm−1, 34 μV K−1, and 1.1 × 10−3 μW m−1 K−2, respectively. The highest power conversion efficiencies of 6.6% and 7.8% were realized by PBDTT-4S-TT and PBDTT-4S-BDD, respectively. These results suggest that 4-methylthio substitution on thiophene side chain of two-dimensional polymers is an effective strategy to enhance the Voc of polymer solar cells.
Conjugated polymers have been extensively used for optoelectronic applications such as photovoltaics, light-emitting diodes, thin-film transistors and electrochromics. Over the past decade, a large number of donor-acceptor type conjugated polymers with an alternating array of electron donors and acceptors have been designed and synthesised for organic electrochromics application.
Conjugated copolymers containing fluorene and diphenylamine moieties with octyl and triethylene glycol side chains have been synthesized via Suzuki-Miyaura cross-coupling reaction and their structures have been characterized. Conjugated polymer nanoparticles and self-organization of the polymers have been prepared by rapid precipitation and solvent diffusion methods, respectively.
Five new donor-acceptor (X-DAD'AD)n type conjugated polymers have been synthesized using different X blocks based on carbazole, fluorene, silafluorene, benzodithiophene, and cyclopentadithiophene (CPDT). The strongly electron donating CPDT unit was used as a central D′ fragment to enhance intramolecular charge transfer interactions along the polymer backbone and reduce the bandgap of the resulting conjugated polymers.