Dual-Site Occupancy Induced Broadband Cyan Emission in Ba2CaB2Si4O14:Ce3+

There is a significant need to identify cyan-emitting phosphors capable of filling the “cyan-gap” (480-520 nm) in full-visible-spectrum phosphor-converted white light-emitting diodes (pc-wLEDs). Here, a new broadband cyan-emitting phosphor enabling to address this challenge is reported. The compound, Ba2CaB2Si4O14:Ce3+, presents a bright cyan emission peaking at 478 nm with a large full width at half maximum of 142 nm (6053 cm-1), and minimal thermal quenching. The photoluminescence properties originate from Ce3+ residing at two different crystallographic sites, a [BaO9] distorted elongated square pyramid and a [CaO6] trigonal prism. This combination results in an efficient, broad emission covering the blue to green region of the visible spectrum. Fabricating a simple dichromatic ultraviolet (λex = 370 nm) pumped pc-wLED using Ba2CaB2Si4O14:Ce3+ along with a commercially available red phosphor demonstrates full-visible-spectrum white light with high color rendering index (Ra ˃ 90) and tunable correlated color temperature, showing this materials potential for achieving high-quality LED-based lighting.