An energy transfer strategy for highly luminescent green-emitting Ce3+/Tb3 codoped Ca2LaHf2Al3O12 garnet phosphors in white light-emitting diodes

Bright, energy-efficient, and stable white lighting sources, such as light-emitting diodes, are desirable to mitigate climate change. A near-ultraviolet-excitable, green-emitting Ca2LaHf2Al3O12:Ce3+,Tb3+ garnet phosphor with high photoluminescence efficiency, prepared by solid-state synthesis, is described. X-ray diffraction Rietveld refinement reveals its garnet structure with space group Ia3d and crystallographic parameters a = b = c =12.528 angstrom, a = b = g = 90 degrees, and V =1966.470 angstrom 3. On 408 nm excitation, it produces bright green light peaking at 543 nm owing to the 5D4->7F5 transition of Tb3+ ions and demonstrates an ultrahigh internal quantum efficiency (80%) and high external quantum efficiency (59.2%). The luminescence intensity of Ca2LaHf2Al3O12:0.05Ce3+,0.6Tb3+ is double that of a Ca2LaHf2Al3O12:0.05Ce3+ green phosphor owing to Ce3+->Tb3+ energy transfer. This Ca2LaHf2Al3O12:0.05Ce3+,0.6Tb3+ green phosphor was used to fabricate a near-UV-pumped white LED device; the resulting luminous efficacy and color rendering index at 3397 K were 17.56 lm/W and 93.1, respectively. (c) 2022 Elsevier Ltd. All rights reserved.