Facile Synthesis of Thienopyrroledione-Based π-Conjugated Polymers via Direct Arylation Polycondensation under Aerobic Conditions

An exploration of the tolerance of a Pd-catalyzed direct arylation polycondensation under aerobic conditions was carried out. The polycondensation of 5-(2-ethylhexyl)thieno-[3,4-c]-pyrrole-4,6-dione with 2,7-dibromo-9,9-dioctylfluorene was accomplished smoothly in air by refluxing the solvents, without the need for additional catalysts or additives. This simple modification allowed the use of commercially available reagent-grade solvents without further purification and produced the corresponding pi-conjugated polymer with a molecular weight and yield comparable to those obtained under conventional oxygen- and moisture-free conditions. The facile synthetic protocol was applicable to the synthesis of other thienopyrroledione-based pi-conjugated polymers. The obtained polymers served as semiconducting materials in organic light-emitting diodes (OLEDs) and organic photovoltaics. The effects of the terminal structure of the polymer on its photoluminescence and OLED device characteristics were also evaluated.