Solid-State Light-Emitting Devices Based on the Tris-Chelated Ruthenium(II) Complex. 2. Tris(bipyridyl)ruthenium(II) as a High-Brightness Emitter

We report high-brightness, high-efficiency, solid-state light-emitting devices based on small-molecule Ru(bpy) 3 (PF 6 ) 2 and its derivatives. These devices operate at low voltage (as low as 2.5 V), suggesting a close parallel with well-documented liquid electrogenerated chemiluminescence cells. We have realized luminance levels as high as 1000 cd/m 2 at only 5 V with spin-cast films and 200 cd/m 2 at 3 V. Emitted light is red or red-orange in color. At low voltage, external quantum efficiencies on the order of 1% are attainable. Luminance levels and efficiencies of these magnitudes are unprecedented in solid-state Ru(bpy) 3 2+ -based devices. A significant time delay is observed between voltage application and device response, as previously reported. We find that the low-voltage time delay can be circumvented using an initial high-voltage pulse, affording nearly instantaneous high brightness.