Perylene diimide derivative dispersed in LDH as a new efficient red-emitting phosphor for LED applications

Perylene diimide-based dyes substituted by four sulfonate groups at their bay position are known to be extremely sensitive to their mutual pi-pi intermolecular interaction. They do not emit fluorescence in solid state. When co-hosted in LDH with a surfactant in extremely small quantities, an absolute photoluminescence quantum yield (PL QY(abs)) of about 35% is reached upon blue excitation at 465 nm for a dye content as low as 0.1% of the total interleaved anions and yet revealing the presence of excimers. When this material is dispersed in silicone, the emission spectrum exhibits a blue shift compared to the hybrid assembly. A saturated red color with PL QY(abs) as high as 50% is obtained. When this red-emitting film is combined with a YAG/Ce silicone film and a blue LED chip emitting at 465 nm, warm white light (T = 3366 K) with a high color rendering index of 91.4 is produced. Finally, the phosphors hosted in LDH are photo-stable even when dispersed in a silicone matrix, with emission properties that do not suffer any decrease in intensity under combined thermal and photonic stresses, thus opening up real possibilities for applications in LED technology.