Highly efficient phosphorescent polymer OLEDs fabricated by screen printing

We demonstrate the use of screen printing in the fabrication of highly efficient phosphorescent polymer organic light-emitting devices (OLEDs) based on a green-emitting Ir(ppy)3 and a host polymer PVK. We incorporate PBD in the polymer host as an electron-transporting dopant and α-NPD as a hole-transporting dopant. The best screen-printed single-layer device exhibits very high peak luminous efficiency of 63 cd/A at a relatively high operating voltage of 17.1 V at the luminance of 650 cd/m2. We observed the highest luminance of 21,000 cd/m2 at 35 V. Due to the high operating voltage, despite of the high peak luminous efficiency the peak power efficiency was found to be 12.2 lm/W at the luminance of 470 cd/m2 (15.9 V).