Efficient charge injection from a high work function metal in high mobility $n$-type polymer field-effect transistors

We demonstrate efficient electron injection from a high work function metal in staggered transistors based on the high mobility poly{[$N,N′$-bis(2-octyldodecyl)-naphthalene-1,4,5,8-bis(dicarboximide)-2,6-diyl]-alt-$5,5′$-(⁠$2,2′$-bithiophene)}. Channel length scaling shows that the linear mobility for electrons remains higher than $0.1cm2/Vs$ when reducing the channel length to a few micrometers. Field-enhanced injection favors downscaling at a fixed lateral voltage and reduces the contact resistance to $11kΩcm$ at high gate voltages for channels of only a few micrometers. The contacts are asymmetric, with the source contribution dominating the overall resistance, consistent with an injection limited regime rather than bulk-limited as generally found in staggered transistors.