Performance Comparison of Organic Transistors with Different Poly(3-Hexyl Thiophene) Solvents

Poly(3-hexylthiophene) (P3HT) as an active layer (organic semiconductor) in organic transistors is of particular interest due to its self-organizing properties to form a microcrystalline structure. Intensive research to improve carrier mobility by several orders of magnitude has shown that the morphology of the organic material is critically affected by the regioregularity, molecular weight, molecular weight distribution and chain stiffness, as well as processing conditions. Many studies have shown that deposition methods, solubility and boiling point of the solvent affect the semiconductor morphology. Boiling point in particular seems to be of obvious importance, since high boiling point solvents evaporate more slowly. This increased evaporation period then gives the polymer chains more time to arrange themselves into a better crystal structure (crystallization) and therefore better performing devices. In this work, the importance of the active layer solvent (P3HT) is demonstrated, by comparing the laboratory results of two classes of devices that after P3HT deposition were baked at the same temperature and time under vacuum and room conditions respectively.