The respective stannylated monomer, brominated monomer, and Pd(PPh3)4 (3:2:5% mol ratio; in case of benzo[1,2-b:3,4-b':5,6-b'']trithiophene (BTT) -1:1:5% mol ratio) were dissolved in anhydrous toluene under inert atmosphere and refluxed for 3 days. In a short time period (1-2 h) the precipitate of polymer started to appear in the reaction flask. After completion of the reaction the precipitate was filtered and washed with hot toluene, DMF, chloroform, THF and methanol (3 times each solvent). Subsequently, Soxhlet extraction was performed using chloroform, THF, and methanol (24 h each solvent). Afterwards the solid was dried in a vacuum drying oven at 120 o C for 24 h. More detailed reaction parameters can be found in Table .