Manufacturing and study of charge transport properties of organic thin film transistors

Author(s)

Alexandre de Castro Maciel

• Document type: Doctoral Thesis
• Press: São Carlos.
• Institution: Universidade de São Paulo (USP). Instituto de Física de São Carlos (IFSC/BT)
• Defense date: 2012-10-26

Examining board members

Roberto Mendonça Faria; Neri Alves; Adriano Reinaldo Viçoto Benvenho; Marco Cremona; Francisco Eduardo Gontijo Guimarães

• Advisor: Roberto Mendonça Faria

Abstract

Digital electronics plays an essential role in the development and maintenance of living standards into practice in the world today. The cornerstone for the creation of this technological age is undoubtedly the transistor. With the advent of new materials, the search for transistors that offer new opportunities in processing and application allowed a new area to be created: the organic electronics. Field effect transistors based on organic thin films have received great attention in recent decades. We report an experimental and theoretical study of field effect transistors based on organic thin films. We characterized transistors manufactured using a derivative of pentacene (TMTES-pentacene) as the active layer in a device and using Si/SiO2 as gate and insulator. We show that the inclusion of the organic semiconductor in an insulating polymeric matrix helps to maintain the termo-mechanical stability of the device. A model was developed that take into account the parasitic resistances and to explain the behavior of the transistor as a function of temperature. We also present the manufacturing and characterization process of transistors using rr-P3HT as semiconductor and PMMA as insulator. We report Top-Gate and Bottom-Gate transistors with maximum mobility of 7 x 10-3 cm2/V.s. The maximun ON/OFF ratio of ~ 900 was found for the optimized transistors. The behavior of the transistors was analyzed as a function of temperature and both gradual channel approximation and Vissenberg-Matters models were applied for extracting the parameters. Finally, we present a channel current model based on the resolution of 2D numerical Poisson equation using the ideas of Vissenberg-Matters to the calculate the concentration of charges due to the local potential. The model, although still in the early stages of development, predicts the saturation current at output simulated curves with no limitation of regime validity. (AU)

• FAPESP's process: 07/07251-8 - Research on transport properties of organic thin films transistors
• Grantee: Alexandre de Castro Maciel
• Support Opportunities: Scholarships in Brazil - Doctorate (Direct)