Eur. Phys. J. Appl. Phys. 33, 175-182 (2006)
https://doi.org/10.1051/epjap:2006022

Field and temperature effects on the electronic mobility in Alq3 structures

Université de Limoges, Faculté des Sciences et Techniques, CNRS – FRE 2701, Laboratoire UMOP, 123 Av. Albert Thomas, 87060 Limoges, France

Corresponding author: amoliton@unilim.fr

Received: 6 September 2005
Revised: 13 October 2005
Accepted: 18 November 2005
Published online: 22 February 2006

Abstract

Tris(8-hydroxyquinoline) aluminium (Alq3) inserted in the structure ITO/Alq3/Al is used to show how dielectric spectroscopy and a representation can separate dielectric conductivity by bound charges from conductivity due to residual pseudo free charges. Coupled with the I(V) characteristic, the representation allow to study the mobility of these carriers as a function of the applied bias voltage V; then the mobility was estimated to be  cm² V⁻¹ s⁻¹ (with V = 0), and we demonstrate that approximately follows a Poole-Frenkel like law. Consequently, these results show that mobility determined by field effects is generally overestimated by around one order of magnitude for an electric field at around 1  MV cm⁻¹. More precisely, we demonstrate that pseudo free charges exhibit a field and weakly temperature dependent mobility, which is in contrast to carriers involved in the trap–charge limited current regime which exhibit a temperature dependent and field independent mobility.