Polarization-tunable electroluminescence using phase retardation based on photonic bandgap liquid crystal

We have demonstrated polarization-tunable electroluminescence (EL) from organic light-emitting diodes (OLEDs) using a combination of polymeric cholesteric liquid crystal (PCLC) and nematic liquid crystal (NLC). By electrically controlling NLC alignment, the proposed EL device shows a continuous polarization tunability including two circular (right and left) and two linear polarizations without loss of light. This simple polarization-tunable EL device is based on photonic-device concept using spin-coatable PCLC. Hence, there is no limitation for choosing emissive materials with high internal efficiency. Also, its polarization tunability will be available in various optical devices and can extend OLED application to photonic technologies.