High-color-quality blue-light-pumped full-spectrum white-light-emitting diodes realized by efficient green-emitting CaY2HfScAl3O12:Ce3+ phosphors

Rare-earth doped inorganic phosphors are critical for solid-state white lighting. Particularly, efficient broadband, blue-light-excitable, green-emitting phosphors are highly needed for fabricating full-spectrum white-light-emitting diodes (WLEDs) with high-color-quality. Herein, we describe a new efficient blue-light-excited CaY2HfScAl3O12:Ce3+ green phosphor with high quantum efficiency (QE) and broad emission bandwidth. X-ray diffraction, scanning electron microscopy, energy-dispersive X-ray spectrometer, excitation and emission spectra, CIE color coordinates, QE values, and temperature-dependent emission spectra have been used to characterize the samples. Rietveld refinement reveals that the CaY2HfScAl3O12 garnet compound has a cubic structure with lattice parameters of a = b = c = 12.38(13) Å, α = β = γ = 90°, and V = 1897.85(6) Å3. Impressively, the Ce3+ ions in the CaY2HfScAl3O12 host exhibit broadband excitation bands in the 300–500 nm spectral range with a maximum at 450 nm. Upon 450 nm excitation, the optimal phosphor doped with 2 mol% Ce3+ shows a broad green emission band in the wavelength range of 460–750 nm peaking around 532 nm, along with full width at half maximum of 121 nm as well as high internal QE of 78.9% and external QE of 46.6%. Ce3+ concentration-dependent luminescence properties and thermal stability at elevated temperature have been comprehensively studied. Finally, a WLED device is fabricated by utilizing CaY2HfScAl3O12:Ce3+ green phosphor, CaAlSiN3:Eu2+ red phosphor and a 450 nm blue LED chip, which generates bright full-spectrum warm-white light with ultrahigh color rendering index (Ra = 98.0, R9 = 97.5) and low correlated color temperature of 3602 K under 180 mA drive current. This work provides new insights into designing and developing efficient green phosphors for full-spectrum LED lighting.