Owing to their excellent optoelectronic properties, poly(3-alkylthiophene)s (P3AT) has been considered as one of the best conjugated polymers for use in organic electronics devices, such as, organic field-effect transistors (OFET), organic light-emitting diodes (OLED), and organic photovoltaics (OPV). Because of the asymmetrical structure of 3-alkylthiophene, there are three possible linkages between two neighboring thiophene units, which leads to the regioregularity issues for P3AT. In comparison with regiorandom P3AT, the regioregular P3ATs exhibit better optoelectronic performance, and have attracted much attention. Synthesis of the regioregular P3AT is, however, more challenging for synthetic polymer scientists. Over the past three decades, various metal-catalyzed C-C coupling reaction have been utilized for synthesis of regioregular P3AT, including McCullough method, Rieke method, Grignard methathesis (GRIM), Suzuki-coupling, Stille-coupling, and C-H activated polymerization. In this mini-review paper, the above mentioned synthetic methods are summarized. The mechanism and advantages of these methods are compared and discussed. The current review paper gives an general overview on the research development on the synthesis of P3AT. In the end, we would like point out that direct C-H activated polymerization is the most promising synthetic method for conjugated polymers due to its high atom economy efficiency. Contents
1 Introduction
2 Regioregularity and applications of poly(3-alkylthiophene)s
2.1 Regioregularity of poly(3-alkylthiophene)s
2.2 Application of poly(3-alkylthiophene)s in the organic electronic devices
3 Methods for the synthesis of poly(3-alkyl-thiophene)s
3.1 Chemical and electrochemical polymerization
3.2 Chemical coupling methods to regiorandom poly(3-alkylthiophene)s
3.3 Synthesis of regioregular poly(3-alkylthiophene) by metal-catalyzed C-C coupling reaction
4 Summary and outlook