**3. Conclusions**

We have fabricated flexible, polarized, and luminous OLEDs using a flexible GBO reflecting polarizer substrate. We have also described the fabrication and investigation of a polarized and luminous OLED and WOLED using a combination of a QWP retardation film and a GBO reflective polarizer. Polarized EL brightnesses of over 10,000 cd/m2 can be produced from the polarized OLED, with high peak efficiencies in excess of 10 cd/A, which are almost double those obtained from the polarized WOLED with only the GBO polarizer. The polarization direction of the EL light emitted from the polarized OLED corresponds to the passing axis of the GBO polarizer used. Furthermore, we have also shown that a high polarization ratio of greater than 35∼40 is possible over the whole emission brightness range. These results show that using the (achromatic) QWP film and the GBO reflective polarizer one can develop bright (W)OLEDs with highly polarized luminescence emissions. It is also noted that the polarization ratio of the polarized WOLED can be further improved by introducing a high quality achromatic QWP film for a wide range of wavelengths including red, green, and blue light. By combining the devices presented here with the luminous EL layers reported elsewhere [35], it may be possible to develop highly efficient polarized OLEDs with a wide range of optical applications. For example, the device structure used in this study can be applied to the design of special light-emitting devices, such as polarized backlights for LC displays. Such devices can also be used for the development of a new class of polarized OLEDs such as polarized surface emitting devices for 3-D displays and/or the polarized light sources of optical waveguide devices.
