Structure, Luminescence, and Application of a Robust Carbidonitride Blue Phosphor (Al<sub>1–<i>x</i></sub>Si<sub><i>x</i></sub>C<sub><i>x</i></sub>N<sub>1–<i>x</i></sub>:Eu<sup>2+</sup>) for Near UV-LED Driven Solid State Lighting

As an extension of nitride luminescent materials, carbidonitride phosphors are also attracting great attention due to their superior thermal stability. This paper reports a blue-emitting carbidonitride phosphor Al<sub>1–<i>x</i></sub>Si<sub><i>x</i></sub>C<sub><i>x</i></sub>N<sub>1–<i>x</i></sub>:Eu<sup>2+</sup> suitable for near ultraviolet (UV) light emitting diodes (LEDs), which is formulated by introducing SiC into AlN:Eu<sup>2+</sup>. With the introduction of carbon (silicon), the lattice abnormally shrinks along both <i>a</i>- and <i>c</i>-axes at low <i>x</i> values (<i>x</i> ≤ 0.08), due to the formation of a dense interlayer for accommodating the luminescence center Eu<sup>2+</sup>. Both of the Raman spectra and solid state NMR spectroscopy show that both Si and C are dissolved in the AlN lattice. A single blue emission band (λ<sub>em</sub> = 472–477 nm) is observed for compositions of <i>x</i> > 0.05 by cathodoluminescence measurements. Under the 365 nm excitation, the maximum luminescence is attained for the composition of <i>x</i> = 0.06 that has an external quantum efficiency of 61% and absorption efficiency of 74.4%, which is about 11–15% higher than the corresponding carbon-free nitride sample. The thermal quenching of Al<sub>1–<i>x</i></sub>Si<sub><i>x</i></sub>C<sub><i>x</i></sub>N<sub>1–<i>x</i></sub>:Eu<sup>2+</sup> reduces with increasing C (SiC) content, and the sample of <i>x</i> = 0.06 shows a small loss of ∼4.0% in quantum efficiency even at 200 °C. Using this phosphor in a near UV-driven white LED, a superhigh color rendering index of Ra = 95.3 and R9 = 72 as well as a color temperature of 3533 K are achieved.