White Hybrid Organic-Inorganic Light-Emitting Diode Using ZnO as the Air-Stable Cathode

A white solution HyLED processed electroluminescence device was obtained using an air stable metal oxide ZnO as the cathode. Poly(9,9-dioctylfluorenyl-2, 7-diyl) (PFO) as the blue emitting host and the iridium (III)bis(2- methyldibenzo-[f,h] quinoxaline (acetylacetonate) (Ir(MDQ)2 (acac) as orange dye was chosen. PFO was dissolved in chlorobenzene and the concentration of the iridium complex was controlled by adding the appropriate amount of a diluted chlorobenzene solution of the orange emitter. The solutions were filtered over a 0.20 μm polytetrafluoroethylene filter and spun on the substrates obtaining a thickness of approximately 70 nm. Cs2CO 3, MoO3, and Au were evaporated in a high vacuum chamber integrated in an inert glovebox atmosphere under a base pressure of 1 × 10-6 mbar. It was observed that when the concentration of the complex is changed, the emission color shifts from a pure orange to the white zone in the middle of the CIE diagram.