ABSTRACT
Uniaxially oriented, form-anisotropic photoluminescent molecules usually exhibit anisotropic optical characteristics, i.e., linearly polarized absorption and emission. Polarized chromatic light, which is essential for a variety of devices and applications, is usually generated by the use of an isotropic light source in combination with a polarizer. This chapter provides a compilation of performance of polarized light-emitting diodes produced by different alignment techniques and with different electroluminescent materials. Most of the early studies on circularly polarized luminescence (CPL) were based on the incorporation of a luminescent achiral chromophore in a chiral nematic or cholesteric liquid crystal. Chiral nematic liquid crystals are intrinsically birefringent and exhibit a helical supra-molecular architecture, which is characterized by the pitch length. There has been a report about bridged triarylamine helicenes exhibiting CPL. These molecules preferentially emit and absorb circularly polarized light without the help of an liquid crystal matrix.
