Lucas Fugikawa Santos

By Lucas Fugikawa Santos and Giovani Gozzi

In this chapter, we present a brief introduction to semiconducting properties of conjugated polymers and the motivation to apply this class of materials in electronic/optoelectronic devices such as polymer light-emitting diodes (PLEDs). We describe, in detail, the operating mechanisms of PLEDs, with particular focus on the effects of charge injection and transport and their dependence on the external electric field and temperature. The mechanisms of current injection from the electrodes into the organic semiconductor are initially treated using traditional models for thermionic emission and tunnelling injection. More recent models considering the influence of metal/semiconductor interface recombination and of energetic and spatial disorder in the injection currents are also introduced and discussed. In addition, models considering space-charge-limited currents and trap-filling-limited currents are employed to describe the charge transport characteristics in the bulk. Furthermore, we present a brief discussion on ideas concerning the effects of the disorder on the charge-carrier transport behaviour.

Part of the book: Conducting Polymers

By João P. Braga, Guilherme R. De Lima, Giovani Gozzi and Lucas Fugikawa Santos

This chapter provides a brief introduction to thin-film transistors (TFTs) based on transparent semiconducting metal oxides (SMOs) with a focus on solution-processed devices. The electrical properties of TFTs comprising different active layer compositions (zinc oxide, aluminum-doped zinc oxide and indium-zinc oxide) produced by spin-coating and spray-pyrolysis deposition are presented and compared. The electrical performance of TFTs is evaluated from parameters as the saturation mobility (μsat), the TFT threshold voltage (Vth) and the on/off current (Ion/Ioff) ratio to demonstrate the dependence on the composition of the device-active layer and on ambient characterization conditions (exposure to UV radiation and to air).

Part of the book: Design, Simulation and Construction of Field Effect Transistors