LIQUID CRYSTAL MATERIALS ORIENTATION USING NEW APPROACH

It is well known that the liquid crystal (LC) mesophase is actively used in display technique and biomedicine devices. Unfortunately, the switching time of the devices based on the LCs is not fast enough; thus, it is very important to find novel perspective ways to obtain the good switching time of the LC dipoles used in these devices. Initial orientation of the LC molecules influences the dynamic parameters, for example, the switch-on and switch-off characteristics and the diffraction efficiency of the final devices. Among the different methods and approaches to find the optimized orientation of the inertial LC molecules a nanotechnology approach has shown the best results. This approach allows increasing the transparency, to decrease the resistivity and the number of the functional layers in the sandwich LC structures. Thus, it results in a decrease in the applied bias voltage. The effect is based on the fact that the ITO coating can be considered as the conducting layer and as the orienting (alignment) layer simultaneously. In the current paper, we continue our steps in the direction to find the best way of the LC molecules orientation. It is proposed to consider the LC media sensitization process as the method to change the surface relief when this relief is prepared from the polymeric orienting materials doped with the carbon nano-objects. Based on the solid fullerene-doped polyimide thin films and other organics it can be shown that the content of the fullerenes influences the wetting angle significantly. The fullerene concentration is correlated with the different surface relief view applied in the aligning of the LC molecules. The switching of the LC can be improved; furthermore the novel relief depended on the fullerene content can be used for the optical limiting of the laser irradiation.

Synthesis and Characterisation of High Fullerene Content Polymers and Their Use in Organic Photovoltaic Devices

Narrow dispersity polymers with a high tethered fullerene content were synthesised by first polymerising poly(chloromethyl styrene) using reversible addition–fragmentation chain transfer (RAFT) polymerisation and subsequently functionalising them with pristine fullerene. The polymers comprised 52 % by weight fullerene, corresponding to approximately one fullerene per monomer in the polymer with a different morphology to poly(3-hexyl thiophene) (P3HT) : phenyl-C61-butyric acid methyl ester (PCBM) systems. Bulk heterojunctions formed from the polymer tethered fullerene (PTF) with P3HT yielded functioning organic photovoltaic devices with power conversion efficiencies ranging from 0.0030 to 0.22 % as the PTF was increased from 1 : 0.8 to 1 : 1.3. Process optimisation resulted in a maximum efficiency of 0.4 %.