Effects of aquaregia treatment of indium–tin–oxide substrates on the behavior of double layered organic light-emitting diodes

Abstract

The effects of a controlled aquaregia treatment of indium–tin–oxide (ITO) substrates on the behavior of highly efficient vacuum evaporated double layered 8-tris-hydroxyquinoline Al $({\mathrm{Alq}}_{\mathrm{3}})$ -based light-emitting diodes are described. It is found that in suitably treated devices, both current injection and the electroluminescence (EL) are significantly enhanced. The enhancement is believed to result from the greater ITO/hole transporting layer contact areas and the contact conditions. The observed dependence of $\mathrm{I(V),}$ the EL output, and the EL efficiency on the ITO surface morphology indicates that space-charge-limited currents dominate the behavior of the devices.