University of Toyama researchers developed the first crystalline OLED, offering promising performance

Researchers from The University of Toyama have developed the world's first OLED that uses a non-epitaxial crystalline rubrene thin film as the emitter layer. To create this OLED device, the researchers combined an amorphous underlayer with precise annealing processes, 

The researchers produced full OLED devices based on this emitter, and discovered that they exhibit a dramatic increase in current density, up to 1000 times higher than that of conventional amorphous devices. The crystalline OLED also achieved an exceptionally low turn-on voltage of 1.3 V at 1 cd/m². 

Finally, the researchers also discovered that the electroluminescence spectrum showed a sharp, single peak characteristic of crystalline structures, suggesting emission derived from a selective transition dipole moment.