We proposed wideband antireflective circular polarizer for realizing a true black state in all viewing directions in organic light-emitting-diode displays (OLEDs). Present commercialized wideband circular polarizer consisted of a half wave and a quarter wave plates having the refractive index parameter (Nz) of 1.5 in both films exhibits light leakage in the oblique viewing directions, deteriorating image quality of a black state. We evaluated Nzs of both films and proposed a new wideband antireflective circular polarizer with a perfect dark state in all viewing directions with Nz = 0.5 in both plates, which will greatly improve image quality of OLEDs.

Recently, polyethylene terephthalate (PET) has been considered as a substitute material for a protection film in a polarizer in order to reduce the cost. However, PET film exhibits high retardation intrinsically due to the stretching process, which induces a chromatic fringe pattern so called a color mura in oblique viewing angle directions, associated with a strong wavelength dispersion. Based on simulation and experimental results, placing an optic axis of PET film in plane can suppress the color mura without the need to use any compensation films; the film thus exhibits high performance as well as low cost.

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Currently, the polyethlene terephthalate (PET) film challenges to substitute Tri-acetyl cellulouse (TAC) film which is a protection film in a polarizer layer, because of low cost of PET film. On the contrary, the PET film shows an optical problem such that color shift or interference optical pattern in oblique direction can occur because the film is made with the lamination process, which induces high phase retardation. In this paper, we propose a color shift free low cost polarizer by polymerization of random oriented reactive mesogen (RM) on the PET film. We calculate the viewing angle performance of the polarizer with the conventional PET film, with the TAC film and with the proposed PET film. As a result, we confirm that the proposed optical configuration can satisfy the optical performance equivalent to that of conventional TAC film uses in addition to the cost-down.