Synthesis and luminescent characteristics of yellow emitting GdSr2AlO5:Ce3+ phosphor for blue light based white LED

A series of Ce3+ ions doped GdSr2AlO5 (GSA) phosphors were synthesized by a citric acid based sol-gel method. The X-ray diffraction patterns confirmed their tetragonal structure after the samples were annealed at 1300 °C, and the scanning electron microscope image showed the closely packed particles. The excitation spectra revealed that the GSA phosphor effectively excited with blue light of 442 nm due to the 4f1→5d1 transition and exhibited yellow emission corresponding to the 5d1→4f1 transition of Ce3+ ions. The optimum doping concentration of Ce3+ ions was 5 mol% and the critical distance was calculated to be ~17 Å. White LEDs were fabricated by combining blue LED (465 nm) chip with Ce3+:GSA phosphor. The CIE chromaticity coordinates (0.34, 0.31) provide their emission potentiality in the white light region.