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The operation principles of the various single chip luminescence conversion (LUCO) white LEDs, that can be realized with blue or ultraviolet (UV) LED chips, are briefly reviewed. In order to demonstrate the feasibility of the so far almost unexplored case of UV pumped tricolor LUCO white LEDs, InxGa1—xN single quantum well LED layer sequences were grown by MOCVD and processed into near‐UV LED pump chips. Europium doped oxide and sulfide phosphors emitting in the blue, the green and the red spectral range were used for UV to visible conversion. With white blends prepared from these phosphors, housed white LEDs with high color quality were realized.

To develop warm‐white light‐emitting diodes via conversion phosphors, blue light‐emitting diodes are generally combined with mixtures of green and red‐emitting phosphor powders. Generally, the phosphors are provided by resin embedded particle dispersions. Such resin‐based solutions cause several drawbacks with respect to LED lifetime and quality. Therefore, it has been investigated whether the red‐emitting nitride phosphor CaAlSiN3:Eu and the green‐emitting oxidic phosphor YAG:Ce can be cofired to layered ceramic composites. The shrinkage behavior and the composition of the interface in dependence of sintering temperature and the effect of interdiffusion processes at the interface on the luminescence properties were investigated. The formation of secondary phases at the interface in the cofired structures was found to limit the phosphor functionality for the nitride‐based CaAlSiN3:Eu in such composite ceramics. To counteract this, sacrificial interlayers were introduced to produce multilayered ceramics comprising CaAlSiN3:Eu and YAG:Ce for LED lighting applications. It is shown for the first time, that it is possible to sinter layered CaAlSiN3:Eu and YAG:Ce composite ceramics in a pressureless process at moderate sintering temperatures if one uses thin‐film passivated interfaces to reduce luminescence‐disturbing diffusion phenomena. These results demonstrate that diffusion barriers can be suitable means to obtain layered ceramic composites comprising CaAlSiN3:Eu and YAG:Ce in a pressureless sintering process with good optical properties.