Charge transport limited by grain boundaries in polycrystalline octithiophene thin film transistors

¹ Faculté des Sciences de Bizerte, 7021 Jarzouna-Bizerte, Tunisia
² Laboratoire de Physique de la Matière Condensée, Groupe Matériaux Moléculaires et Polymères, Campus Universitaire, 1060 Tunis, Tunisia
³ Laboratoire des Matériaux Moléculaires, CNRS, 2 rue Henry-Dunant, 94320 Thiais, France

Corresponding author: Ramzi.Bourguiga@fsb.rnu.tn

Received: 27 July 2000
Revised: 28 November 2001
Accepted: 18 February 2002
Published online: 24 July 2002

Abstract

Organic filed-effect transistor (OFETs) based on polycrystalline “octithiophene” has been realized. The current-voltage characteristics at low drain voltage has been used to derive the mobility of organic field effects transistors (OFETs). It appears that the data must be corrected for the substantial source and drain contact resistance. The carrier mobility is found to increase quasi linearly with gate voltage at room temperature. The temperature dependent measurements show that the mobility is thermally activated and becomes practically temperature independent at low temperatures. A model based on trapping mechanism, in which it is assumed that charge transport is limited by grain boundaries, has been used to describe the carrier mobility in polycrystalline “octithiophene” thin film transistors measured at temperatures ranging from 10 K to 300 K.