Pulsed gate voltage measurement for charge mobility extraction of organic transistors

The field-effect mobility of organic semiconductors is an important parameter that describes a physical characteristic of charge carriers and is extracted from the current–voltage characteristics of field-effect transistors. For the parameter to be consistent with its physical definition, charge transport in organic semiconductors should be in a steady state. However, charge transport in organic field-effect transistors is often in a non-steady state because of the occurrence of charge-carrier trapping and the Joule heating effect; therefore, careful attention is required for the extraction of the field-effect mobility in such cases. In this study, the effects of gate pulses on the transport characteristics of organic field-effect transistors are investigated. Consequently, an ideal sequence of gate pulses to minimize the effects of intermediate trap states and Joule-heating during extraction of the field-effect mobility of organic transistors is proposed. Finally, an equation that relates the field-effect mobility to the sequence of gate pulses is derived and experimentally validated.