Structure-processing-property relationships in solution processable organic semiconducting polymers are both complex and important. High throughput screening techniques present a potential advantage in defining empirical relationships between processing conditions and device performance. Using microfluidic devices and a substrate annealing gradient system, large arrays of organic thinfilm transistors (OTFTs) are fabricated from poly(didodecylquaterthiophene-altdidodecylbithiazole).