Nanocomposite Field Effect Transistors based on Zinc oxide/polymer blends

Significant progress is being made in the realization of thin-film transistors (TFTs) for application in various electronic devices and circuits [1-5]. Currently, one of the important challenges in this area is to design low-cost and stable organic semiconductors that possess high field-effect mobilities for constructing low-power high-speed transistor devices. However, there are only limited stable and cheap organic semiconductors that are applicable for OTFT applications. Here, we report the work in our laboratory that focus on stable, inexpensive and high field-effect mobility nano-composite materials for the potential application in OTFT technologies. Solution processed polymer based nano-composite field effect transistors with wide band gap semi-conducting ZnO nano-tetrapods and nano-crystals dispersed in the polymer matrix were utilized to study the field effect behaviour. The electrical characteristics of polymer based wide band gap nano-crystal or nano-tetrapod composite devices exhibit an increase in the hole mobility up to two orders of magnitude higher than the pristine polymer. The fabricated devices that contained a layer of MEH-PPV only exhibited p-channel behaviour with a hole mobility up to 10^-4 cm²/Vs, similar to previously reported.³ Figures 1a and 1b show the TEM (transmission electron microscope) images of ZnO nanocrystals or tetrapods dispersed in MEH-PPV solutions, respectively. The size of the nanocrystals is around 5 nm (Figure 1a) and the legs of the tetrapods are around 100 nm in width (Figure 1b). Figure 2 shows the electrical behaviour of the devices fabricated from MEH-PPV and nanocomposite with ZnO nanocrystals or tetrapods.