Efficient, Color‐Stable, and Long‐Lived White Organic Light‐Emitting Diodes Utilizing Phosphorescent Molecular Aggregates

Highly efficient and stable single‐stack hybrid white organic light‐emitting diode (WOLED) devices are developed using two emissive layers: one with amber‐colored phosphorescent molecular‐aggregate emission from the Pd(II) complex, Pd(II) 7‐(3‐(pyridine‐2‐yl‐κN)phenoxy‐κC)(benzo‐κC)([ c ]benzo[4,5]imidazo‐κN)[1,2‐ a ][1,5]naphthyridine, Pd3O8‐Py5, and the other with blue fluorescence emission. An optimized device structure achieves high color stability under various current densities, an external quantum efficiency (EQE) of 45.5%, a power efficiency of 97.4 Lm W −1 , and an estimated LT 95 (operational time to 95% of the initial luminance) of 50 744 h at an initial luminance of 1000 cd m −2 .