A novel strategy for high color purity virescent Er³⁺-doped SrLaAlO₄ nanocrystals for solid-state lighting applications

Unique down-conversion virescent SrLaAlO₄:Er³⁺ nanocrystals were successfully fabricated by urea-assisted solution combustion route. Presence of tetragonal phase in doped samples [SrLa_(1−x)Er_xAlO₄ (x = 0.1–4.0 mol%)] with a space group of 14/mmm (139) was investigated by powder X-ray diffractometry and Rietveld refinement analysis. Nanocubic crystals with their size ranging from 45 to 55 nm were displayed by scanning electron microscopy and transmission electron microscopy (TEM) techniques while high-resolution TEM highlighted the (105) crystallite plane by representing the resolved fringes of lattice. Nanocrystalline nature and the (101) crystal plane was depicted by selected area electron diffraction patterns of the powder sample. Qualitative as well as quantitative elemental composition of nanophosphors were investigated by mapping and spectra of energy dispersive X-ray analysis, respectively. On near UV excitation, photoluminescence emission spectra showed a prominent band of green color due to ⁴S_3/2 → ⁴I_15/2 transition (549 nm). Energy bandgap and refractive index of optimized sample were determined as 4.97 eV and 1.736, respectively, via diffuse reflectance spectra. Color chromaticity coordinates (0.1735, 0.6909) of SrLa_0.98Er_0.02AlO₄ nanophosphors verified their virescent emission with a color purity of 100% and were found to be consistent with the standard values of European Broadcasting Unit (EBU) as well as International Telecommunication Union, thus reflected their important role as the green component in the solid-state lighting devices, especially red–green–blue pc-white light-emitting diodes.