Preparation of blue-cyan phosphor Sr1-yAl2-xGaxSi2O8:yCe3+ for high-color-rendering white LEDs via a cation substitution strategy

To achieve high-color-rendering WLED devices, exploration of blue‒cyan phosphors that can be excited by near-ultraviolet (NUV) chips is particularly important to compensate for the cyan gap. In this work, feldspar-structured Sr 1-y Al 2- x Ga x Si 2 O 8 :yCe 3+ blue-cyan phosphors were prepared via a high-temperature solid-phase method and a cation substitution strategy. The luminescence performance of the Sr 0.96 Al 2 Si 2 O 8 :0.04Ce 3+ sample was improved by applying the cation substitution strategy of partially replacing Al 3+ with Ga 3+ , and the representative sample Sr 0.96 Al 1.4 Ga 0.6 Si 2 O 8 :0.04Ce 3+ was obtained. The luminescence intensity increased threefold for the Sr 0.96 Al 1.4 Ga 0.6 Si 2 O 8 :0.04Ce 3+ compound compared to Sr 0.96 Al 2 Si 2 O 8 :0.04Ce 3+ , and a broadband blue‒cyan phosphor with a half-height width of 100 nm was obtained. The representative sample Sr 0.96 Al 1.4 Ga 0.6 Si 2 O 8 :0.04Ce 3+ showed relatively good thermal stability. Sr 0.96 Al 1.4 Ga 0.6 Si 2 O 8 :0.04Ce 3+ was combined with 365 nm NUV LED chips and commercial (Sr, Ca)AlSiN 3 :Eu 2+ to obtain WLED devices with color rendering index (Ra) as high as 94.8 and correlated color temperatures (CCTs) as high as 4831.4 K. These results show that the blue-cyan phosphor complements the cyan component while simplifying the manufacturing process of WLEDs.