The present invention relates to fluorescent diketopyrrolopyrroles ('DPPs') of Formula (I), wherein A1 and A2 independently from each other stand for (II) wherein R1, R2 and R5 to R11 are as defined in claim 1, a process for their preparation and their use for the preparation of inks, colorants, pigmented plastics for coating, non-impact-printing material, color filters, cosmetics, or for the preparation of polymeric ink particles, toners, dye lasers and electroluminescent devices. The fluorescent diketopyrrolopyrroles ('DPPs') of Formula (I) exhibit a high lightfastness, a high heat stability, especially in plastics. A luminescent device comprising a DPP compound of Formula (I) is high in the efficiency of electrical energy utilisation, high in luminance and high in colour purity.