Photoluminescence properties of glassy yttrium aluminum borate powders: dopant-free phosphors for solid-state lighting

Abstract

Glassy yttrium aluminum borate powders (g-YAB) obtained by the polymeric precursor method show intense photoluminescence (PL) in the visible range under near-ultraviolet (NUV) excitations. The PL properties strongly depend on the thermal treatment of powders as well as the excitation wavelengths. The broad PL of g-YAB powders cover whole visible spectral range between 380 nm and 780 nm under NUV excitations. The PL internal quantum yield (i-QY) was determined using the integrating sphere method and is found to reach up to 91 ± 5% under 365 nm light emitting diode (LED) excitation. Moreover, the associated color coordinates in transmission mode revealed preferably warm-white light with correlated color temperature (CCT) tunable between 2800 K and 5300 K, ideal for general household and workplace lighting. The use of NUV-LED excitation accompanied with broadband visible emission profile helps in achieving high color-rendering ability with color-rendering index (CRI) higher than 90. Furthermore, these g-YAB phosphors exhibit excellent PL thermal stability (> 200 °C) and stability with time under device operating conditions. The overall favorable PL properties and low cost synthesis suggest huge potential of g-YAB phosphors as new lanthanide (Ln)-free white light phosphors with very high CRI under NUV-violet LED excitations.