Micro lens design for efficiency improvement of red organic light-emitting diode

We have proposed a micro lens to improve the luminance of red organic light-emitting devices (ROLEDs). The micro lenses were applied on the glass/indium tin oxide (ITO)/OLED. The size, thickness and diameter of micro lenses were calculated by using FDTD (finite-difference timedomain) method. Simulations were performed for 5 µm and 10 µm sized. The thickness and the gap of the micro lens were both 1 µm. The material of the micro lenses was silicon dioxide. The highest luminance of an OLED applied with a micro lens was 11,185 cd/m 2 , at on approval voltage of 14.5 V, The efficiency of the device with a micro lens increased by 3 times compared to that of the device with no micro lens.