Effect of the molecular weight of the polymer gate dielectric on the performances of solution-processed ambipolar OTFTs

Abstract

Gate dielectrics in organic thin-film transistors (TFTs) play a vital role in governing the overall performance of the device since the charge transport channel is formed in the active layer of the device at the interface with the dielectric. In this article the influence of the molecular weight (M_w) of the polymer dielectric on the electrical performances of an ambipolar TFT is explored. The transport of both electrons and holes is probed in devices integrating two different polymer dielectrics with three different M_w. We found that the molecular weight plays a subtle role on the major device parameters such as field-effect mobility, threshold and on voltage as well as sub-threshold slope. Furthermore, the use of a top-gate architecture provides general importance to our results given that the surface properties of the dielectrics do not affect the growth mechanisms of the already-deposited amorphous semiconductor polymer.