Dual-site occupancy induced broadband cyan emission in Ba2CaB2Si4O14:Ce3+

Abstract

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 that enables addressing of 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 (λ_ex = 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 (R_a > 90) and tunable correlated color temperature, showing the potential of this material for achieving high-quality LED-based lighting.