Electroluminescent phosphor, method for producing the same and device containing the same
An electroluminescent phosphor comprising: ZnS-based phosphor particles and a coating layer provided on a surface of the particle, wherein the particles have an average particle size of from 0.1 to 20 μm, and a coefficient of variation in a particle size distribution of less than 35%, and a content of particles having 10 or more stacking faults with an interplanar spacing of 5 nm or less is 30% or more based on all of the ZnS-based phosphor particles.
1 . An electroluminescent phosphor comprising: ZnS-based phosphor particles and a coating layer provided on a surface of the particle, wherein the particles have an average particle size of from 0.1 to 20 μm, and a coefficient of variation in a particle size distribution of less than 35%, and a content of particles having 10 or more stacking faults with an interplanar spacing of 5 nm or less is 30% or more based on all of the ZnS-based phosphor particles.
2 . The electroluminescent phosphor as claimed in claim 1 , wherein the average particle size of the particles is from 15 to 20 μm.
3 . The electroluminescent phosphor as claimed in claim 1 , wherein a ratio of an average thickness of the coating layer to the average particle size of the particles is from 0.001 to 0.1.
4 . The electroluminescent phosphor as claimed in claim 1 , wherein the ZnS-based phosphor particles contain at least one element selected from the group consisting of Cu, Mn, Ag and rare earth elements.
5 . The electroluminescent phosphor as claimed in claim 1 , wherein the ZnS-based phosphor particles contain at least one element selected from the group consisting of Cl, Br, I and Al.
6 . The electroluminescent phosphor as claimed in claim 1 , wherein the ZnS-based phosphor particles contain at least one element selected from the group consisting of Au, Sb, Bi, Cs and Pt.
7 . The electroluminescent phosphor as claimed in claim 1 , wherein the ZnS-based phosphor particles contain 1×10 −7 to 5×10 −4 mol of Au per mol of ZnS.
8 . The electroluminescent phosphor as claimed in claim 1 , wherein the ZnS-based phosphor particles contain 1×10 −7 to 1×10 −3 mol of Pt per mol of ZnS.
9 . The electroluminescent phosphor as claimed in claim 1 , wherein the coating layer contains at least one compound selected from the group consisting of oxides, nitrides, hydroxides, fluorides, phosphates, diamond carbon and organic compounds.
10 . A method for producing an electroluminescent phosphor as claimed in claim 1 , which comprises while fluidizing the ZnS-based phosphor particles in a presence of a fluidization promoter having a larger average particle size than the average particle size of the particles, supplying a material for making the coating layer thereto and piling up the material on a surface of the particles or reacting the material with the particles so as to form the coating layer.
11 . A dispersion type electroluminescent device comprising: an opposing pair of electrodes at least one of which is transparent; a phosphor layer provided between the electrodes; and a dielectric layer provided between the electrodes, wherein the phosphor layer contains the electroluminescent phosphor as claimed in claim 1 .
12 . The dispersion type electroluminescent device as claimed in claim 11 , wherein the phosphor layer has a thickness of from 40 to 100 μm.
13 . The dispersion type electroluminescent device as claimed in claim 11 , further comprising an intermediate layer provided between the transparent electrode and the phosphor layer.
14 . The dispersion type electroluminescent device as claimed in claim 13 , wherein the intermediate layer contains at least one of an organic polymer compound and an inorganic compound, and the intermediate layer has a thickness of from 10 nm to 100 μm.