Developing optically active polymers for next-generation television and computer displays

Using a liquid crystal as a model, researcherwas able to create optically active polymers capable of converting light into circular polarization. This method may aid in lowering the cost of smart displays.

Nowadays, entering an electronic store can be overwhelming, especially if you end up in the television section. While prices have decreased, TV sizes have significantly increased in recent years. This is primarily due to the adoption of organic light emitting devices (OLEDs), which are polymers based on carbon that can emit light at wavelengths that can be adjusted.

These conjugated polymers, which contain alternating single and double bonds, are both electrically conductive and can be colored by chemically doping them with other molecules. Their oxidation state can also be rapidly altered through the application of an electric voltage, which alters their hue. However, future progress may necessitate the development of new materials that can take advantage of optical properties such as circular polarization.

Developing optically active polymers for next-generation television and computer displays (Illustrative image).

Using a sacrificial liquid crystal template, a researcher from the University of Tsukuba has now developed a method for producing polymers locked into a helical configuration. According to the author Professor Hiromasa Goto, "Polymers that both have optical activity and luminescent function can emit circularly polarized light".

The liquid crystal molecules were initially arranged straight for this process. The helical configuration of the liquid crystals was brought about by the addition of monomer molecules. As a result, the structure is imprinted with a "chirality" or handedness that determines whether it is oriented clockwise or counterclockwise. The application of an electric voltage triggered the polymerization of the monomers. The liquid crystal template was then eliminated, leaving behind a polymer solidified in a helical configuration.

By destroying the mirror symmetry, the polymer can convert linearly polarized light to circular polarization. The polymer's furan rings help stabilize the helical structure in addition to enhancing electrical conductivity. According to Professor Goto, the polymer can aggregate into a highly ordered chiral system due to the interactions between the rings known as pi-stacking. Circular dichroism absorption spectroscopy was used to test the resulting polymer, and it was discovered to have significant optical activity at visible wavelengths. Future uses of this method could involve more affordable and energy-efficient electronic displays.

Reference:Hiromasa Goto. Reaction field induction self-amplification optical activity during polymerization in liquid crystal. Molecular Crystals and Liquid Crystals, 2022; 1 DOI: 10.1080/15421406.2022.2073421