Hybrid GaN/organic microstructured light-emitting devices via ink-jet printing

We report what we believe to be the first use of organic nanostructures for efficient colour conversion of gallium nitride light emitting diodes (LEDs). The particular nanomaterials, based on star-shaped truxene oligofluorenes, offer an attractive alternative to inorganic colloidal quantum dots in the search for novel and functional 'nanophosphors'. The truxenes have been formed into a composite with photoresist and ink-jet printed onto microstructured gallium nitride LEDs, resulting in a demonstrator hybrid microdisplay technology with pixel size ~32μm. The output power density of the hybrid device was measured to be ~8.4mW/cm2 per pixel at driving current density of 870.8A/cm2 and the efficiency of colour conversion at drive current of 7mA was estimated to be approximately 50%.