Injection and Transport of High Current Density over 1000 A/cm2 in Organic Light Emitting Diodes under Pulse Excitation

Abstract

We succeeded in injecting and transporting a maximum high current density of J=1163 A/cm² in organic light-emitting diodes using short-pulse excitation combined with a highly thermally conductive silicon substrate (thermal conductivity: 148 W m^-1 K^-1) and a small cathode configuration (cathode radius r=50 µm). A maximum current density almost 20 times higher than that associated with direct current (DC) operation was observed by driving an OLED with a short pulse voltage. With short-pulse excitation, the decrease in external quantum efficiency (η_ext) obeyed a typical singlet–singlet exciton annihilation model well, indicating that the generation of Joule heat in OLEDs can be suppressed under pulse operation.