Blue Light Emitting Polymers and Devices

Blue light-emitting polymers are critically important for the development of full-color polymer displays. A number of such polymers have been synthesized, with high photoluminescence and electroluminescence efficiencies. Both polymer light-emitting diodes (LEDs) and electrochemical cells have been fabricated, but various materials issues remain to be solved. Device lifetimes have been limited, due to factors such as (1) the instability of the polymers which usually have low glass transition temperature, and (2) accelerated failure at the polymer/electrode interfaces, due to high charge injection barriers and the blue polymers' low charge carrier mobility. Using dual functional triarylamine moieties as the side groups, we have prepared new blue light-emitting poly(paraphenylenes) exhibiting high luminescent efficiency, high glass transition temperature, good environmental stability, and enhanced carrier mobility. Blue LEDs have been demonstrated with 4.2 cd/A efficiency and 360 cd/m 2 brightness at 8 V.