Highly efficient crystalline organic light-emitting diodes

Abstract

Crystalline organic light-emitting diodes (OLEDs) have attracted continuous attention due to their capacity to withstand high current densities. Although crystalline OLEDs are of great potential for achieving electrically pumped organic lasers, the poor performance of these devices impedes their application. Therefore, the improvement of the performance of crystalline OLEDs is highly desirable. Here, this paper reports a para-sexiphenyl (p-6P)/tris(8-hydroxyquinoline) aluminum (Alq₃) OLED with high efficiency based on high-quality crystalline films. The p-6P/Alq₃ crystalline OLED exhibits a high external quantum efficiency (EQE) of 1.44% at ∼5000 cd m⁻², which is >100 times more than other reported crystalline OLEDs. At high driving current density, the results show that the p-6P/Alq₃ crystalline OLED exhibits better survivability than a p-6P/Alq₃ amorphous OLED. This work provides a prototype of highly-efficient crystalline OLEDs, making crystalline OLEDs one of the choices to achieve electrically pumped organic lasers in the future.