Fig. 4

Linear polarization from spectrally narrowed EL in cavity-based OLEDs. θ is the angle between the polarization axis of linear polarizer and ITO stripe in cavity-based OLEDs. a Linearly polarized EL measured at 3.0 cm distance from cavity-based OLEDs with different Q-factors. b Linearly polarized EL measured at 0.5 cm and 3.0 cm distances for high-Q device