Polarised electroluminescence

One application for organic electroluminescent materials is in the construction of lightweight backlights for LC displays (see Chapter 3, section 3.8). If organic electroluminescent (OEL) materials emitted polarised light they could make the polariser... 

An additional advantage of the use of reactive, photopolymerisable liquid crystalline monomers with charge transfer or electroluminescent properties is the ability to generate circularly and linearly polarised light. This possibility... 

The macroscopic alignment of polymer chains was also achieved by depositing soluble poly(p-phenylenes), such as 37 or poly(3-thiophenes) such as 26, from solution by the Langmuir-Blodgett technique. However, low polarisation ratios ( u/ x) were found for electroluminescence (3 1). 

Low polarisation ratios (<2 1) for absorption had also been found for amorphous PPV (1) deposited from solution by spin-coating on rubbed poly(tetrafluoroethylene) [PTFE]. It is evident that this could be improved on by making use of the high order parameter and self-organising properties of the nematic phase of liquid crystalline electroluminescent polymers such as those (16, 28 and 78-82) shown in Table 6.16. - 2 ° This was then found subsequently to be the case using thermotropic liquid crystalline polyfluorenes, such as 28 and 80 shown in Table 6.6 and segmented PPV derivatives, such as 81. The nematic phase exhibits the lowest viscosity of... 

Figure 6.7 Plot of the relative intensity (A.U.) of polarised electroluminescence against wavelength (nm) of a bilayer OLED consisting of an electron-transport and emission layer represented by a nematic network formed by polymerising compound (86) with isotropic UV light and a combined hole-transport and a coumarin non-contact alignment layer doped with 4.4,4-tris(naphthylyl)-N-(phenylamino) triphenylamine.

Figure 8 (right) Polarised electroluminescence spectra from an ITOtruhhed PPVtPFOl Ca LED. The upper curve is for light emitted with polarisation parallel to the orientation direction and the lower curve for perpendicular polarisation. The anisotropy, IparaUei I perpendicular, hos a peak valuc of 25 1. 

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