With rising energy costs and the increasing prominence of mobile devices, power efficiency is becoming more and more significant in today's world. In general, a high current efficiency of OLEDs is dependent on two factors: the emission layer and a good charge carrier balance. Provided the current efficiency remains unchanged, these factors, in combination with a very low driving voltage, produce high power efficiency. Using its proprietary PIN technology, Novaled is able to combine very low operating voltages, while simultaneously maintaining a good charge carrier balance and high current efficiency. This has resulted in extremely high reported power efficiencies for PIN OLEDs.
Using a long-lifetime stacked white OLED and an advanced outcoupling solution, Novaled has demonstrated a power efficiency of 50.7 lm/W at a brightness of 1000 cd/m2 with warm-white colour coordinates of 0.45/0.45. The power efficiency has been measured with a calibrated integrating sphere including the light emitted in the forward direction only. By collecting the total light in the device using a macroscopic lens, a power efficiency as high as 85 lm/W has been measured.
Extremely high efficiencies have been achieved also with monochrome OLEDs using optimized organic layer stacks with doped transport layers, e.g., 120 lm/W at 1,000 cd/m2 in a green bottom emission PIN OLED.
Power efficiencies of a white PIN OLED stack with different outcoupling solutions
