Chun Yoon

We designed and synthesized two novel blue pyrrole derivatives, 2-(3-cyano-4-(4-(dibutylamino)phenyl)-5-oxo-1,5-dihydro-2H-pyrrol-2-ylidene)malononitrile (BAPCP) and 2-(3-cyano-4-(4-(dihexylamino)phenyl)-5-oxo-1,5-dihydro-2H-pyrrol-2-ylidene)malononitrile (HAPCP), as potential candidates for use in image sensor color filters. The properties of these new compounds were evaluated, focusing on their optical and thermal characteristics in solution and color filter film forms. The molar extinction coefficient values of BAPCP and HAPCP in solution were 6.03 × 10⁴ and 6.91 × 10⁴ L/mol·cm. The molar extinction coefficient of HAPCP was 4.5 times higher than that of the commercially used Disperse Blue 359. The synthesized compounds exhibited transmittance values that meet commercial requirements, with 88.6% at 450 nm and 0.73% at 530 nm. Both newly synthesized compounds met the decomposition temperature requirement of over 230 °C, which is necessary for the manufacturing process of image sensor color filters. The decomposition temperatures of both compounds were approximately 19 °C higher than that of Disperse Blue 359. When the thermal stability of color filter films for image sensors was evaluated, BAPCP demonstrated excellent optical properties before and after thermal stability testing, maintaining its characteristics in an optimized molecular form. Accordingly, BAPCP appears to have favorable potential as a blue colorant for image sensors, attributed to its superior optical and thermal stability characteristics.

Two new yellow azo pyridone derivatives, (E)-6-hydroxy-1-(3-methoxypropyl)-4-methyl-2-oxo-5-(p-tolyldiazenyl)-1,2-dihydropyridine-3-carbonitrile (APY-M) and 5,5′-((1E,1′E)-(methylenebis(4,1-phenylene))bis(diazene-2,1-diyl))bis(6-hydroxy-4-methyl-2-oxo-1,2-dihydropyridine-3-carbonitrile) (APY-D), were designed and synthesized as yellow colorants for image sensors. The properties of these new compounds were evaluated in both solution and color filter film forms, focusing on their optical and thermal characteristics. The molar extinction coefficient values of APY-M and APY-D in solution were found to be 2.7 × 10⁵ and 3.0 × 10⁵ L/mol·cm, respectively. The transmittance of the newly synthesized compounds met commercial requirements, showing values below 0.21% at 435 nm and above 97.1% at 530 nm. APY-D exhibited a molar extinction coefficient value in solution that was 1.15 times higher than that of the commercially used yellow colorant Disperse Yellow 241. Both newly synthesized compounds satisfied the decomposition temperature requirement of over 230 °C, which is essential for the color filter manufacturing process in image sensors. In particular, APY-D, with its dimeric structure and increased molecular weight, demonstrated enhanced thermal stability, with a 50 °C increase in decomposition temperature compared to Disperse Yellow 241. Color filter films for image sensors were fabricated using the new compounds, and their thermal resistance was evaluated. APY-D maintained its transmittance due to the enhanced thermal stability provided by its dimer structure and increased molecular weight. Consequently, APY-D is anticipated to be a promising candidate for use as a yellow colorant in image sensors, owing to its excellent optical and thermal properties.

Novel yellow azo pyridone dye derivatives were synthesized for use in image-sensor color filters. The synthesized compounds have a basic chemical structure composed of azo, hydroxy, amide, and nitrile groups as well as different halide groups. New materials were evaluated on the basis of their optical, thermal, and surface properties under conditions mimicking those of a commercial device fabrication process. A comparison of their related performance revealed that, among the four prepared compounds, 5-((4,6-dichlorocyclohexa-2,4-dien-1-yl)diazenyl)-6-hydroxy-1,4-dimethyl-2-oxo-1,2-dihydropyridine-3-carbonitrile (Cl-PAMOPC) exhibited the best performance as an image-sensor color filter material, including a solubility greater than 0.1 wt% in propylene glycol monomethyl ether acetate solvent, a high decomposition temperature of 263 °C, and stable color difference values of 4.93 and 3.88 after a thermal treatment and a solvent-resistance test, respectively. The results suggest that Cl-PAMOPC can be used as a green dye additive in an image-sensor colorant.

Six red dyes derived from quinacridone pigment (C. I. Pigment Red 122) were prepared by introducing an N-alkyl group or N-acyl group in the quinacridone ring. The characteristics of the synthesized dyes were examined by absorption maxima, solubility and thermogravimetric analysis (TGA). The introduction of N-alkyl group gave very little bathochromic shift of 2∼3 nm, whereas the presence of a withdrawing group at the nitrogen exhibited a large hypsochromic shift of 60∼45nm comparing to that of C. I. Pigment Red 122 which is unsubstitued at the nitrogen atom. In terms of weight reduction at 250°C, N-alkyl groups withstood to the thermal decomposition in comparison with the behavior of withdrawing groups at the position of nitrogen atom. The solubility of six dyes was dramatically increased by the introduction of N-substituent which clearly indicates their character as a dye rather than a pigment.

We have designed and synthesized six phthalocyanine dyes and one benzoperylene dye for dye-based green Liquid Crystal Display (LCD) color filters. The solubility, spectral properties and thermal stability of the prepared six phthalocyanine dyes varied depending on their isomeric structures and core metals. They were dissolved in industrial solvent–binder composites and spin coated with and without yellow compensating benzoperylene dye into dye-based LCD color filters. The prepared color filters exhibited superior optical properties compared to conventional pigment-based ones due to the fluorescence of benzoperylene dye and less light scattering resulting from the smaller particle size of the dyes. The phthalocyanine dyes substituted at the peripheral (β) positions showed enough thermal stability for color filters and the yellow benzoperylene dye effectively compensated the spectra for vivid green colors.

The color properties of liquid-crystal displays are usually classified on the basis of color representations, contrast ratios, and brightness, which primarily depend on the properties of pigments. Among these classifications, the contrast ratio can be improved by minimizing the light scattering of the pigment particles, which is directly related to the degree of dispersion. Therefore, synergists are usually applied to increase the contrast ratio by augmenting the efficiency of the dispersion. In this study, synergists containing anthraquinone as a backbone were synthesized and then their performance in improving the contrast ratio was examined.

Drop‐on‐demand ink‐jet inks made from dyes usually show poor light fastness and poor water fastness. Therefore, many researchers have introduced pigments into ink‐jet inks to overcome the defects of dye‐based ink. Pigmented ink needs sophisticated technology which disperses the pigments stably in low viscosity. Thus, adequate dispersants are essential to achieve stable dispersions of pigments for ink‐jet inks. This study describes syntheses of dispersants, properties of formulations and comparisons of performance with an existing ink to assess their suitability for commercial application.