All Polymer FETs Direct-Written on Flexible Substrates Achieving MHz Operation Regime

We report the successful combination of digital, direct-writing techniques, such as inkjet printing and femtosecond laser writing in order to fabricate megahertz operating, all-polymer FETs on flexible substrates without the use of any mask. By a control of the layout of the device, maximizing the ratio between the channel area with respect to the total gate overlap area through a simple interdigitated scheme, the frequency of transition f
_T
for an n-type polymer FET can be enhanced up to 4.9 MHz.