Polarizing element or polarizing plate for display device with blue light emitting element

Abstract

[Problem] The present invention relates to a polarizing element and a polarizing plate, which can improve contrast and enhance color display characteristics in an organic electroluminescent display device. [Solution] A substrate having a polarizing function and containing an azo compound is controlled such that the substrate alone has a transmittance of 45% to 60%, the average transmittance of 440-nm to 500-nm wavelengths for one substrate is 50% or more, and the average transmittance of 550-nm to 650-nm wavelengths as obtained by measuring two substrates arranged such that the absorption axis directions thereof are orthogonal to one another is 10% or less.

Description

technical field [0001] The present invention relates to a polarizing element or a polarizing plate for organic electroluminescence. Background technique [0002] A polarizing element is generally produced by adsorbing and aligning iodine as a dichroic dye or a dichroic dye on a polyvinyl alcohol resin film. On at least one side of the polarizing element, a protective film made of triacetyl cellulose or the like is attached via an adhesive layer to form a polarizing plate, which is used in a liquid crystal display device or the like. A polarizing plate using iodine as a dichroic dye is called an iodine-based polarizing plate, and a polarizing plate using a dichroic dye as a dichroic dye is called a dye-based polarizing plate. Among them, dye-based polarizers are characterized by high heat resistance, high humidity and heat durability, high stability, and high color selectivity by mixing. On the other hand, they have the following problems: When comparing polarizing plates, ...

AI Technical Summary

Problems solved by technology

Among them, dye-based polarizers are characterized by high heat resistance, high humidity and heat durability, high stability, and high color selectivity by mixing. On the other hand, they have the following problems: When comparing polarizers, the transmittance, that is, the contrast is lower than that of iodine-based polarizers

However, the transmittance of such iodine-based polarizers is 35% to 44%, so there is a problem that the brightness is greatly reduced

Furthermore, it absorbs more light of 400nm to 500nm belonging to the short-wavelength side of visible light, so for example, the OLEDs described in Patent Document 3 and Patent Document 4, and the blue luminous efficiency of OLEDs that have strong light emission near 460 nm decrease, Therefore, the brightness is reduced and the color display is insufficient

In response to such a large decrease in luminance, it is considered that the use of an iodine-based polarizer with a transmittance of 45% to 60% can prevent the decrease in luminance, but the durability of the iodine-based polarizer is poor, and long-term use will eventually lead to a decrease in luminance , so the reliability is obviously insufficient

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