Preparation of thermally stable red dyes derived from diketo-pyrrolo- pyrrole pigment for LCD color filter

6 dyes derived from Diketo-pyrrolo-pyrrole pigment were prepared by introducing an Nalkyl group, an N-acyl group or an N-aryl group to the DPP-ring. Absorption maxima, thermal stability by a thermogravimetric analysis (TGA), and the chromatic characteristics of the fabricated films were measured. It was explained that the observed hypsochromic shift and the effects of N-substituent on thermal stability of the dyes as well as a chromaticity diagram.