Anisotropy of charge carrier transport in PCPDTBT field-effect transistor structures

Abstract

In this paper we are analyzing anisotropy of hole mobility in the organic field-effect transistor structures with an active layer of PCPDTBT (poly[2,6-(4,4-bis-(2-ethylhexyl)-4H-cyclopenta [2,1-b;3,4-b′]dithiophene)-alt-4,7(2,1,3-benzothiadiazole)]). Hole mobility and its dependence on the temperature was measured by i-CELIV and current transients methods. The combination of both techniques allowed us to obtain results of hole mobilities in perpendicular and parallel to the substrate directions. In the same temperature range differential scanning calorimetry (DSC) measurements were performed to detect morphological changes in the active layer of the field-effect transistor structure. From obtained results of mobility dependence on temperature, energetic disorder parameter of Bässler’s Gaussian Disorder Model (GDM) was estimated. DSC data and hole transport data demonstrated that the change in PCPDTBT’s morphology is responsible for the abrupt decrease of hole mobility on temperature in the field-effect transistor structure.