Highly power efficient organic light-emitting devices enabled by phosphorescent and p-i-n technologies

Abstract

Organic light-emitting devices (OLEDs) containing highly efficient phosphorescent emitters and highly conductive doped organic transport layers were studied. Saturated red devices with luminous efficiency of 15 cd/A operate at <4 V; hence, they have a record power efficiency of 12 lm/W at 1,000 cd/m². Additionally, two high-efficiency red OLEDs were serially connected and vertically stacked to create a stacked OLED having a luminous and power efficiency (at 1,000 cd/m²) of 28 cd/A and 12 lm/W, respectively. The electrical connection between the two OLEDs is enabled by molecular p- and n-type doped organic transport layers. The single emissive layer red OLED has a projected lifetime (time to half initial luminance) of ~150,000 hrs from an initial brightness of 500 cd/m². The stacked device shows very similar lifetime characteristics when driven at similar currents, which results in significantly prolonged lifetime of ~260,000 hrs at an initial luminance of 500 cd/m².