An international team has investigated a newly synthesized liquid-crystalline material that promises applications in optoelectronics. Simple rod-shaped molecules with a single center of chirality self-assemble into helical structures at room temperature. Using soft X-ray resonant scattering at BESSY II, the scientists have now been able to determine the pitch of the helical structure with high precision. Their results indicate an extremely short pitch at only about 100 nanometres which would enable applications with particularly fast switching processes.
Liquid crystals are not solid, but some of their physical properties are directional – like in a crystal. This is because their molecules can arrange themselves into certain patterns. The best-known applications include flat screens and digital displays. They are based on pixels of liquid crystals whose optical properties can be switched by electric fields.
Some liquid crystals form the so-called cholesteric phases: the molecules self-assemble into helical structures, which are characterised by pitch and rotate either to the right or to the left. “The pitch of the cholesteric spirals determines how quickly they react to an applied electric field,” explains Dr. Alevtina Smekhova, physicist at HZB and first author of the study, which has now been published in Soft Matter.
Read more on the HZB website
Image: The photo shows the cells on the modified sample holder which was used in the real experiment. This modified sample holder is mounted within the ALICE chamber at BESSY II.
Credit: © A. Smekhova/HZB