A no-hysteresis TIPS–pentacene:polystyrene blend-based organic field effect transistor by extruded direct ink writing and the application in a resistive load inverter circuit

Abstract

Organic field effect transistors (OFETs), with the active layer made from 6,13-bis(triisopropylsilylethinyl) pentacene:polystyrene blend films, were fabricated on rigid (glass) and flexible (polyethylene terephthalate) substrates using a motor-controlled extrusion-based Direct Ink Writing printing method. The characteristics of OFETs fabricated at different in situ annealing temperatures (25, 40, 55, 70 and 85 °C) were explored. We find that the OFET with 25 °C in situ annealing temperature exhibits better performance with improved carrier mobility of 0.14 cm² V⁻¹ s⁻¹, I_ON/I_OFF ratio of 2.7 × 10³, threshold voltage of 0.14 V, and minimal hysteresis compared to other annealing temperature schemes. Moreover, bending tests were performed on flexible devices using three different bending radii (1/2.54, 0.75/1.91 and 0.5/1.27 inch/cm) which were swept continuously. Results indicate that the ON current monotonically decreases as the bending radius is reduced. In addition, a resistive load inverter circuit, formed by connecting an OFET to an external resistive load, can achieve a gain of 2.6 at a V_DD of −80 V and R_L of 100 MΩ. Furthermore, long-term stability of the inverter was investigated over a one-month period. Our analysis shows that there are minimal differences in both the switching threshold voltage and gain, with one-month standard deviations of 1.77 and 0.28, respectively.