Selective molecular tailoring for retarders with achromaticity or a wide field-of-view

Abstract

Optical retarders are key components of opto-electronic devices. Depending on the intended use, achromaticity of phase retardation or a wide field of view (FOV) is required. This paper examines molecular designs that can selectively maximize the achromaticity of phase 2 retardation or FOV using H-shaped reactive mesogen (HRM) molecules with alkyl chains of different lengths. A retarder film made with shorter HRM molecules had a wider FOV, while a retarder made with longer HRM molecules exhibited superior achromaticity of phase retardation. To identify any correlations among the molecular structure, orientation, and the optical properties, the molecular orientation was measured using optical retardation and ultraviolet-visible light absorption anisotropy. Theoretical calculations using density functional theory were performed to confirm the suggested model. We found that the orientation of the molecules rather than their intrinsic polarizability plays a critical role in their optical properties.