Methods to improve the fluorescence intensity of CaS:Eu2+ red-emitting phosphor for white LED

Photoluminescence properties of a novel red fluoride K2LiGaF6:Mn4+nanophosphor

“…Currently most of the available red phosphors still have certain problems. 10,11 For example, oxide phosphors [12][13][14][15][16] cannot absorb blue light efficiently and sulde phosphors [17][18][19] are unstable because of their high sensitivity to hydrolysis reactions. As for the nitride phosphors, [20][21][22][23] they have overlapping re-absorption with the yellow phosphor and the synthesis conditions are rigid.…”

Preparation, Characterization and Photoluminescence Properties of Ca1-xSrxS:Eu Red-emitting Phosphors for a White LED

“…[12][13][14][15] CaS:Eu and SrS:Eu are good red-emitting candidate phosphors for three-band phosphor-converted white LEDs pumped by blue LEDs, since both phosphors have a strong absorption at 455 nm due to the 4f → 5d transitions of the doping Eu. 16,17 The emission peaks of Ca 1-x Sr x S:Eu are located from 618 to 655 nm, and correspond to the transition from the lower 4f 6 5d 1 (T 2g ) state to the 4f 7 ( 8 S 7/2 ) ground state. However, relatively little is known about the optical properties of solid solutions of CaS:Eu and SrS:Eu phosphors for use in lighting applications.…”

Changes in the moisture stability of CaS:Eu2+ phosphors with surface coating methods

“…Among the red phosphors, CaS:Eu 2+ is considered as the most promising red emitting phosphor because of its a deep red emission with nice color purity. [9][10][11][12][13] However, the application of CaS:Eu 2+ has been limited by their instability when exposed to moisture. The problems with red phosphors should be solved for the advancement of white LEDs.…”

“…[10][11][12][13][14][15][16] Various alkaline earth sulfides with rare earth ion activators exhibiting performance advantages over the CaS:Eu 2+ red phosphors have been introduced. However, the application of alkaline earth sulfides has been limited by their instability.…”

“…From a stability point of view, a layer-like homogeneous coating would be also preferred over an island-like inhomogeneous coating. [13][14][15][16][17][18] In this study, coating of the phosphor with silica nanoparticles was performed using five different techniques to improve moisture stability of CaS:Eu 2+ red phosphor and to minimize the decrease in PL intensity. Changes in the morphology, PL intensity, and moisture stability of the phosphor with coating were explored.…”