Photoluminescence Properties and Fabrication of Red-Emitting LEDs based on Ca₉Eu(VO₄)₇ Phosphor

Abstract

We study the photoluminescence properties of the red-emitting phosphor Ca 9 Eu(VO 4) 7 and establish a strong red emission centered at 613 nm under excitation at 395 nm (near ultra violet light, near-UV light) due to the intra-configurational 5 D 0 → 7 F 2 transition within the 4f 6 configuration of the Eu 3+ ions. The intensity of the emitted light decreases with increasing temperature and at T = 470 K about 50% of the intensity of the emitted light at room temperature is lost. Five different red-LED prototypes were constructed by applying a mixture of Ca 9 Eu(VO 4) 7 phosphor and silicone gel on the headers of near-UV LED chips. The prototypes showed a color output from violet for the lowest phosphor concentration (133 g phosphor /l silicone gel), reaching an almost pure red-light output for the highest phosphor concentration (670 g phosphor /l silicone gel). The luminous efficiency of optical radiation (LER) was found to decrease slightly with increasing applied current. For the highest phosphor concentration, the LER decreases from 238 lmW −1 for 1 mA current supply to 235 lmW −1 for 18 mA current supply. The external quantum efficiency decreased from 7.33% for the lowest phosphor containing LED prototype to 4.13% for the highest one.

Eu3+‐activated red phosphor Ca3YAl3B4O15 with low thermal quenching behaviour

“…The sharp excitation peaks were 319 nm ( 7 F 0 → 5 H 3 ), 361 nm ( 7 F 0 → 5 D 4 ), 376 and 383 nm ( 7 F 0 → 5 L 7 ), 396 nm ( 7 F 0 → 5 L 6 ), 413 nm ( 7 F 0 → 5 D 3 ), and 464 nm ( 7 F 0 → 5 D 2 ). [ 29,30 ] The normalized CT band was inserted in Figure 5(a). With the increase in Eu‐doping concentration, the CT band showed a red‐shift trend.…”

“…5 D 2 ). [29,30] The normalized CT band was inserted in Figure 5(a). With the increase in Eu-doping concentration, the CT band showed a red-shift trend.…”

Self-Reduction Mechanism and Luminescence Properties of Eu2+-Eu3+Doped Ca(PO3)2 Phosphor

“…Eu ions are commonly used as activators in commercial phosphors due to the strong 5 D 0 → 7 F J (J = 0,1,2,3,4) transition in the spectral region of Eu 3+ -doped materials, and are therefore widely used in red-orange light materials. [6][7][8][9][10][11] The emission of Eu 2+ is strongly influenced by the crystal field and the covalency of the matrix lattice. In recent years, the main method of obtaining Eu 2+ has been the use of reducing atmospheres such as H 2 .…”