Temperature Dependence in Emission Characteristics of an Organic EL Cell with 8‐hydroxyquinoline Aluminum Emitting Layer

Abstract

Current density‐voltage characteristics, luminance, and emission spectra of an organic electroluminescent (EL) cell were measured at temperatures between −160 and 20°C. An aromatic diamine and 8‐hydroxyquinoline aluminum were used as the hole transport and the emitting layers, respectively. The EL luminance at a constant current density of 1 mA/cm2 was found to decrease with increasing temperature, and the photoluminescence intensity of the powder was also found to show a similar temperature dependence. From these results, the EL luminance is concluded to depend on the fluorescence efficiency of the emitting molecules. Furthermore, a decreased efficiency of exciton generation with increasing temperature is expected.