Optical properties of CaSrSiO4:Eu2+ phosphors prepared by using a solid-state reaction method for white light-emitting diodes

• Published in: Journal of the Korean Physical Society 2015, 67(3), , pp.556-562
• Main Authors: Kwon, Bong-Joon, Gandhi, Sakthivel, Woo, Hyun-Joo, Cho, Kyungmi, Lee, Ho Sueb, Jang, Kiwan, Shin, Dong-Soo, Jeong, Jung Hyun
• Format: Article
• Language: English
• Subjects: Mathematical and Computational Physics; Particle and Nuclear Physics; Physics; Physics and Astronomy; Theoretical; 물리학
• ISSN: 0374-4884; 1976-8524
• DOI: 10.3938/jkps.67.556

We have studied the optical properties of CaSrSiO 4 :Eu 2+ phosphors synthesized by using the conventional solid-state reaction method and the role of Eu 3+ minority ions in those phosphors. The maximum photoluminescence integrated peak intensity was observed for the Ca 1− x Sr 1− x SiO 4 :2 x Eu 2+ (2 x = 0.0050) phosphor. A red shift of 3 nm from 510 to 513 nm in the emission wavelength of the CaSrSiO 4 :Eu 2+ phosphors was observed with increasing Eu concentration. Under an excitation of 244 nm, the Ca 1− x Sr 1− x SiO 4 :2 x Eu 2+ (2 x = 0.0050) phosphor showed a broad emission band at about 515 nm due to the 4 f 6 5 d 1 → 4 f 7 transition of the Eu 2+ and small sharp peaks at about 594, 612, and 701 nm corresponding to the 5 D 0 - 7 F J transitions of Eu 3+ . The existence of Eu 3+ minority ions in the phosphor resulted in a broader full width at half maximum in the emission of the phosphor at the excitation wavelength of 390 ~ 400 nm, even at low Eu concentration. The white light-emitting diodes (LEDs) were fabricated by using the CaSrSiO 4 :Eu 2+ phosphors and 400-nm GaN-based LED chips and exhibited a high color rendering index of ~ 95 and correlated color temperature of ~ 5370 K. The broad emissions of the CaSrSiO 4 :Eu 2+ phosphors combined with the GaN-based LED chips are suitable for the realization of white LEDs.