New yellow Ba_0.93Eu_0.07Al₂O₄ phosphor for warm-white light-emitting diodes through single-emitting-center conversion

Phosphor-converted white light-emitting diodes for indoor illumination need to be warm-white (i.e., correlated color temperature,<4000 K) with good color rendition (i.e., color rendering index >.80). However, no single-phosphor, single-emitting-center-converted white light-emitting diodes can simultaneously satisfy the color temperature and rendition requirements due to the lack of sufficient red spectral component in the phosphors' emission spectrum. Here, we report a new yellow Ba_0.93Eu_0.07Al ₂O₄ phosphor that has a new orthorhombic lattice structure and exhibits a broad yellow photoluminescence band with sufficient red spectral component. Warm-white emissions with correlated color temperature <4000 K and color rendering index >80 were readily achieved when combining the Ba_0.93Eu_0.07Al₂O₄ phosphor with a blue light-emitting diode (440-470 nm). This study demonstrates that warm-white light-emitting diodes with high color rendition (i.e., color rendering index .80) can be achieved based on single-phosphor, single-emitting-center conversion.