The nematic phase is generally used in LC displays. The molecular requirement is the calamitic structure to form the nematic phase. The other properties the molecules need to have depend on the application and function of the liquid crystal display.
For example, a display should work at particularly high or low temperatures, depending on the application. This means that the melting point should be low and the clearing point high.
The image formation is based on changes and reformation of the order of liquid crystal phases. For this to happen, the molecules are modulated in an electric field. Therefore, the molecules must show sufficient polarity (De), which results from uneven charge distribution in the molecule. Depending on the display technology, the polarity can be oriented both in the direction of the molecular axis (positive) or perpendicular to it (negative).
The molecules are moved within the electric field. The lower the viscosity (g1) of the material, the easier it is and the faster an image can be formed.