Jun Choi

Synthesis and characterization of thermally stable dyes with improved optical properties for dye-based LCD color filters

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.

Synthesis and characterization of bay-substituted perylene dyes for LCD black matrix of low dielectric constant

Organic dyes with low electrical conductivity have recently been suggested as replacements for Cr/CrOx and carbon black in developing black matrices with low dielectric constants for liquid crystal displays (LCDs). Two perylene diimide dyes with broad absorption spectra were synthesized, and dye-type, hybrid-type and carbon black-type black matrices were fabricated using one of the dyes. Donating groups were substituted on the bay positions of the dyes by C–N coupling to enhance their solubility in propylene glycol methyl ether acetate, one of the most widely used industrial solvents in the LCD manufacturing processes. The thermal and spectral properties of the dyes were studied by thermogravimetric analysis and UV–Visible spectroscopy. Furthermore, the thermal, optical and dielectric properties of the black matrices were examined by color spectroscopy, optical density measurement and impedance analysis. The hybrid-type black matrix showed promising results with a low dielectric constant, low transmittance spectrum and high thermal stability.