Stannylation of 4-4′-Bis(1-bromo) and 4-4′-Bis(1-bromo) dicyclopenta[2,1-b:3,4-b′]dithiophene-bis(5-fluoro-7-(5′-hexyl-[2,2′-bithiophene]-5-yl)benzo[c][1,2,5]thiadiazole)