Triarylmethane Color Filter for Blue Pixels
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Solution Overview
Problem
Conventional triarylmethane compounds used in blue pixel portions of color filters for liquid crystal displays suffer from unsatisfactory heat resistance and light resistance, leading to changes in hue over time, especially under high temperatures or light irradiation, which limits their ability to maintain brightness.
Innovation Solution
A triarylmethane compound with a specified heteropolyoxometalate anion, such as (P2Mo y W18-y O62)6-, is used, which improves heat resistance and light resistance by minimizing hue changes, allowing for higher brightness and stability over time.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If a triarylmethane pigment (e.g., C.I. Pigment Blue 1) is used in the blue pixel portion to increase brightness, then brightness is improved, but heat resistance and light resistance deteriorate, causing hue changes over time under high temperature or light irradiation
Solution Approach 1:
The invention changes the chemical structure parameters of the triarylmethane compound by introducing specific substituent groups (electron-withdrawing groups like -NO2, -CN, -CF3 at positions 3 and 3'; electron-donating groups like -OH, -OCH3, -OCF3 at positions 2 and 2') and selecting specific counter anions (heteropoly acid anions such as phosphotungstomolybdic acid, phosphomolybdic acid, or tungstomolybdic acid). These parameter changes in molecular structure and composition simultaneously achieve high brightness and improved heat/light resistance, resolving the contradiction between brightness enhancement and stability maintenance.
2Illumination intensity
If conventional triarylmethane pigments are used, then brightness is increased compared to copper phthalocyanine pigments, but the pigments undergo hue changes over long periods under heat history at 200°C or more or under light irradiation
Solution Approach 1:
The invention creates a composite structure by combining a specifically substituted triarylmethane cation with heteropoly acid anions (such as phosphotungstomolybdic acid, phosphomolybdic acid, or tungstomolybdic acid). This composite material approach, where the stable heteropoly acid anion complex acts as a counter ion to the triarylmethane cation, provides both high brightness from the triarylmethane chromophore and exceptional color stability from the heteropoly acid complex, resolving the contradiction between brightness and color stability.
Data Source
Figure 1~3
AI summary
The present invention provides a triarylmethane compound and a color filter containing the compound in a blue pixel portion, the triarylmethane compound being capable of providing a colored material which causes a small change in hue over a long period of time even under heat history at a high temperature or under light irradiation. For example, when used for preparing a blue pixel portion of a color filter, the triarylmethane compound is capable of providing a liquid crystal display device or the like which can provide a high-brightness liquid crystal display having excellent brightness over a long period of time even under a high temperature or light irradiation. The triarylmethane compound contains, as a counter anion for a basic triarylmethane dye cation, a heteropolyoxometalate anion represented by (P2MoyW18-yO62)6-/6 wherein y = an integer of 1, 2, or 3, and the color filter contains the triarylmethane compound in a blue pixel portion.