Polarized light from OLEDs

OLED display manufacturers have so far used circular polarizers borrowed from the LCD technology to improve contrast (Trapani et al, 2003). This approach does not require introduction of new layers in the OLED structure and results in reflectance similar to that of glass. However, polarizers are expensive, generally not flexible, and absorb a substantial amount of the light (up to 40%) (Wu, 2005). 

Fig. 7.7 Polarized electroluminescence from an ITO/rubbed PPV/aligned PFO/Ca OLED. Spectra are shown for light polarized parallel open triangles) and perpendicular open circles) to the rubbing direction. Polarization ratio. 25 1...

Large-area, polarized white OLEDs may become attractive as backlights for LCD displays, since the first polarizer which absorbs at least 50% of the incoming light can be omitted. Nevertheless the efficiency of polarized OLEDs from reactive... 

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