Effect of dye structure on orientational behavior and transition dipole moments in coatable guest–host polarizers

• Guest–host coatable polarizers exhibited the highest dichroic ratio within the permissible limit of guest concentration.
• The dye with high polarity had a lower dichroic ratio as compared to the dye with low polarity.
• The transition dipole moment of the dyes was calculated to investigate its influence on the dichroic ratio.

Guest–host coatable polarizers were manufactured by liquid crystalline polymers and dichroic azo dyes. The highest dichroic ratio of the polarizers was observed within the permissible limit of guest concentration, because any increase in the guest concentrations beyond the permissible limit decreased the alignment ability of the host. The orientational behavior of dye molecules in guest–host systems tend to be more sensitive to intermolecular steric hindrance as compared to that in PVA-based polarizing films. Also, the polarity difference between guest and host molecules had a great effect on the alignment of the guest–host system. Long conjugation, abundant π-electrons for transfer and the charge distribution without deviation from the long axis are required for a highly anisotropic transition dipole moment.

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