Tailoring Trap Density of States through Impedance Analysis for Flexible Organic Field-Effect Transistors

The selection of dielectric material impacts the dielectric/semiconductor (D/S) interface which plays a significant role in defining the device performance. Hence, investigation of the D/S interfacial defects and trap states is essential for improving the device performance and designing new semiconductor and dielectric materials for organic field effect transistors (OFET). Here, the trap density of states (DOS) at the interface is investigated by impedance spectroscopy (IS). OFETs are fabricated with three different dielectric combinations and the highest mobility is found to be 0.12 cm(2) V-1 s(-1). Detailed analysis of the semiconductor thin film and the D/S interface is performed by atomic force microscopy, photoluminescence, time-resolved photoluminescence and is found consistent with the DOS analysis. This work validates that IS can be utilized as a prospective DOS analysis method for OFET applications. Finally, for evaluating the potential application of the device architecture toward developing flexible electronic circuit components, the device is fabricated on a flexible substrate and the mechanical stability is examined by subjecting the device to a strain of 2.5%. The device shows no significant degradation in operation, confirming its practical utility.