End-emitting nano organic light emitting diodes (OLEDs) with directional output

We report a new strategy for the design of organic light emitting diodes (OLEDs), where nanoscale OLEDs are fabricated into a large-area periodic array with their emission propagating along the active layer and being coupled out through the end facets. A large-area template dielectric grating is produced by interference lithography. The OLED devices are then produced on the side walls of the template grating lines, where each device is carried by the back of a grating line and has a width of <300 nm and a height of about 270 nm. The emission is coupled out of the device on the end facet window after a maximum propagation length of shorter than 300 nm through the active layer, reducing largely metallic absorption by the electrodes and overcoming the optical loss by waveguide confinement. Furthermore, such a configuration enables directional concentration of the output emission. The nanoscale OLEDs also imply large potentials for integration into optoelectronic systems.