Using an Optimized Calendering Process with a Grey-Based Taguchi Method to Enhance the Performance of a Printed OTFT

摘要

Researchers typically evaluate the electrical performance of a printed OTFT by the on-off ratio and the field effect mobility, both influenced largely by the roughness of the surface of the gate dielectric layer. In this work, we applied a particular treatment process, called calendering, to the gate dielectric layer after printing to reduce its surface roughness. We fabricated bottom-gate, bottom-contact OTFT samples on a PET substrate with printing and coating methods. We used gravure printing (first gate electrode and second gate dielectric layer), inkjet printing (third source/drain electrode layer), and spin coating (fourth channel layer) for fabrication. Though three kinds of calendering factors with three levels required 27 experimental sets, the Taguchi method enabled the full factorial experiment with only nine sets of calendering process parameters. As a result of experiments using a grey-based Taguchi method, we obtained an optimal set of calendering process parameters. With the optimized calendering process, the on-off ratio and the field effect mobility of the OTFT samples were 1.27x10(4) and 0.0067 cm(2)/Vs, respectively. Compared to the non-calendered samples, these results showed a 40.28% improvement in the on-off ratio and a 43.28% increase in the field effect mobility.