Unipolar-to-ambipolar conversion of organic thin-film transistors by organosilane self-assembled monolayer.

Simplification of the design and manufacture of electronic and optoelectronic devices, such as field-effect transistors and light emitting diodes, can be achieved with the use of organic semiconductor materials. Organic thin-film field-effect transistors (TFFETs) can be used to complement current metal-oxide semiconductor technology, provided that organic ambipolar transistors can be configured to operate in both p-channel and n-channel configurations. The development of organic ambipolar TFFETs has been hindered by the lack of n-type conduction in most of the common organic TFFETs. Here, we show that we can achieve high ambipolar carrier mobility in TFFETs based on rubrene and pentacene molecules through the inclusion of an organosilane self-assembled monolayer (SAM) on the gate dielectric surface. A similar device that lacks the aforementioned SAM exhibits only p-type characteristics, confirming that the enhancement of the n-type conductivity is due to the passivation of the dielectric surface that results from the inclusion of organosilane monolayer.