Polarization-Induced Transport: A Comparative Study of Ferroelectric and Non-Ferroelectric Dielectric-Gated Organic Field-Effect Transistors

What is it about?

Charge transport in organic thin film transistors has received a lot of interest, both experimentally and theoretically. Although the general mechanism of transport in organic transistors, within the framework of localized states giving rise to hopping transport and polaronic models, has been realized in many works, the exact nature of polarization dominated transport is not very well understood. Polymer ferroelectric dielectrics such as PVDF-TrFE, permitting access to an order of magnitude range of dielectric constants with temperature as a tuning parameter, pave the way for monitoring transport as the polarization strength is tuned.

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Why is it important?

A comparative study of ferroelectric and non-ferroelectric-gated organic field-effect transistors (FETs) have been carried out by using a small molecule semiconductor 6,13 bis(triisopropylsilylethynyl) pentacene (TIPS-pentacene) to understand the fundamental aspects of carrier transport in FET architectures. Temperature-dependent current-voltage characteristics from non-ferroelectric dielectric-gated FETs show a clear activated transport, while using PVDF-TrFE a negative temperature coefficient of the carrier mobility is observed beyond 200 K. Comparing PVDF-TrFE based TIPS-pentacene FETs with non-ferroelectric high κ dielectric such as Al2O3, our results conclusively show that the polarization fluctuation, inherent to a ferroelectric dielectric, is responsible for the band-like transport behavior.