Correlation between Physical and Electrical Properties in Pentacene and C8-BTBT-based Organic Thin Film Transistors

Abstract

Physical and electrical properties in pentacene and C8-BTBT-based organic thin film transistors (OTFTs) were investigated. Pentacene and C8-BTBT-based OTFTs were fabricated with various types of interfacial layer to the dielectric surface. Nine types of interfacial layers have been studied: without, CT4112, PMMA, CYTOP, OTS, HMDS, Ta₂O₅, Si₃N₄ and HfO₂. The physical and electrical properties of OTFTs including carrier mobility, threshold voltage, and on/off ratio were measured so that the relationship between the properties can be investigated. Strong correlation between contact angle and threshold voltage was confirmed. It was observed that high correlation coefficient (R) between contact angle and threshold voltage was 0.83 for the pentacene and 0.61 for C8-BTBT-based OTFTs. We also investigated correlation between XRD intensity and carrier mobility. Carrier mobility for pentacene-based OTFTs correlates with the XRD intensity (R=0.80). In contrast, carrier mobility for C8-BTBT-based OTFTs shows independency on XRD intensity (R=0.37).