Full-Spectrum White Light-Emitting Diodes Enabled by an Efficient Broadband Green-Emitting CaYZrScAlO:Ce Garnet Phosphor.

Phosphor-containing white light-emitting diodes (LEDs) with low color-correlated temperatures (CCTs) and high color rendering indexes (CRIs) are highly desirable for energy-efficient and environmentally friendly solid-state light sources. Here, we report a new and efficient blue light-excited, green-emitting Ce-activated CaYZrScAlO phosphor, which underpins the fabrication of high-color quality and full-visible-spectrum warm-white LED devices with ultrahigh CRI values (Ra > 96 and R9 > 96). A family of CaYZrScAlO:Ce phosphors with different Ce dopant concentrations were prepared by high-temperature solid-state synthesis. X-ray diffraction and corresponding Rietveld refinement reveal a garnet structure with an 3̅ space group and crystallographic parameters = = = 12.39645(8) Å, α = β = γ = 90°, and = 1904.99(4) Å. Luminescence properties were studied in detail as a function of Ce with the optimal concentration 1% mol. Impressively, CaYZrScAlO:1%Ce exhibits a broad excitation band from 370 to 500 nm, peaking at ∼421 nm, which is well matched with emission from commercial blue LED chips. Under 421 nm excitation, the CaYZrScAlO:1%Ce phosphor produces dazzling green light in a wide emission band from 435 to 750 nm (emission peak: 514 nm; full width at half-maximum: 113 nm), with a high internal quantum efficiency of 63.1% and good resistance to thermal quenching (activation energy of 0.28 eV). A white LED device combining a 450 nm blue LED chip with CaYZrScAlO:1%Ce green phosphor and commercial CaAlSiN:Eu red phosphor as color converters demonstrates bright warm-white light with excellent CIE color coordinates of (0.3938, 0.3819), low CCT of 3696 K, high CRI (Ra = 96.9, R9 = 98.2), and high luminous efficacy of 45.04 lm W under a 20 mA driving current. New green phosphors enable the design and implementation of efficient luminescent materials for healthy solid-state lighting.