How does a liquid-crystal display work

We observe that liquid crystals can flow like any other viscous liquid, but they also possess some of the properties of crystalline solids, such as physical order, rather than random chaos. Unlike most other liquids, liquid crystals have some properties 

Applying a voltage to a pixel within the cell causes the molecules to move, aligning themselves parallel with the electric field imparted by the electrodes. This realignment destroys the helical structure, precluding the unhindered transmission of light, and the display appears black. 

Molecules of this type are influenced by an external electric field because they possess a dipole one end of the molecule is electron withdrawing while the other is electron attracting, with the result that one end possesses a higher electron density than the other. As a result, the molecule behaves much like a miniature bar magnet. Applying a voltage between the two 

A physicist would say the liquid crystal adopted a twisted nematic structure. 

There have been a large number of attempts to quantify electronegativities x either theoretically or semi-empirically, but none has been wholly successful. All the better methods rely on bond strengths or the physical dimensions of atoms. 

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