Pentacene-based ambipoalr organic transistors with improve n-channel characteristics using polyethylenimine as a buffer layer

In this study, we investigated pentacene-based ambipolar organic transistors using a linear polyethylenimine (LPEI) as gate dielectric buffer layer. We found that introducing an insulating LPEI layer between the pentacene active channel and the polymethylmetacrylate gate dielectric layer could enhance the n-channel electrical characteristics, such as early-on threshold voltage (V
_th
), sharp subthreshold swing (SS), and enlarged on/off current ratio, despite the surface of the LPEI layer disfavoring the growth of the high-quality pentacene active layer. These results were supported by frequency-dependent conductivity measurements, that is, the decreased interfacial trap density and mean interface trap time constant of the devices with the LPEI layer. In summary, the LPEI layer could improve the n-channel characteristics of pentacene-based ambipolar organic transistors to make them suitable for a vast range of potential applications.