Effects of solvents and vacancies on the electrical hysteresis characteristics in regioregular poly(3-hexylthiophene) organic thin-film transistors

The role of residual solvents and vacancies within poly(3-hexylthiophene) (P3HT) active layers, which are made from different boiling point (bp) solvents, on the electrical hysteresis characteristics of P3HT-based transistors was investigated. The improved electrical performance and reduced hysteresis of P3HT films, which are spin coated by high bp solvents, can be interpreted by superior crystalline quality and homogeneity and low vacancies. The hysteresis is dominated by the vacancy-related charge traps in the semiconductor created during film solidification and subsequence solvent evaporation. Furthermore, residual solvents, which initially occupied the vacancies, can contribute to conductivity of regioregular P3HT, thus altering electrical properties and smaller hysteresis.