Solid-state light emitting devices and signage with photoluminescence wavelength conversion and photoluminescent compositions therefor

Abstract

A photoluminescent composition (“phosphor ink”) comprises a suspension of particles of at least one blue light (380 nm to 480 nm) excitable phosphor material in a light transmissive liquid binder in which the weight loading of at least one phosphor material to binder material is in a range 40% to 75%. The binder can be U.V. curable, thermally curable, solvent based or a combination thereof and comprise a polymer resin; a monomer resin, an acrylic, a silicone or a fluorinated polymer. The composition can further comprise particles of a light reflective material suspended in the liquid binder. Photoluminescence wavelength conversion components; solid-state light emitting devices; light emitting signage surfaces and light emitting signage utilizing the composition are disclosed.

1 . A photoluminescent composition comprising: a suspension of particles of at least one phosphor material in a light transmissive liquid binder wherein the at least one phosphor material is excitable by blue light of wavelength 380 nm to 480 nm and wherein the weight loading of at least one phosphor material to binder material is in a range 40% to 75%. 
     
     
         2 . The composition of  claim 1 , wherein the composition is configured to be deposited using a method selected from the group consisting of: screen printing; inkjet printing; letterpress printing, gravure printing; flexograph printing and pad printing. 
     
     
         3 . The composition of  claim 1 , wherein the binder is selected from the group consisting of being: U.V. curable; thermally curable; solvent based and combinations thereof. 
     
     
         4 . The composition of  claim 1 , wherein the binder has a viscosity selected from the group consisting of: 0.5 Pa·s to 5 Pa·s and 1 Pa·s to 2.5 Pa·s. 
     
     
         5 . The composition of  claim 1 , wherein the binder is selected from the group consisting of: a polymer resin; a monomer resin; an acrylic, a silicone and a fluorinated polymer. 
     
     
         6 . The composition of  claim 1 , wherein the binder has in a cured state an elasticity in a range 300% to 500%. 
     
     
         7 . The composition of  claim 1 , wherein the at least one phosphor material has an average particle size selected from the group consisting of: 2 μm to 60 μm, 10 μm to 20 μm and about 15 μm. 
     
     
         8 . The composition of  claim 1 , wherein the at least one phosphor material is selected from the group consisting of: a silicate phosphor; an orthosilicate phosphor; a nitride phosphor; an oxy-nitride phosphor; a sulfate phosphor, an oxy-sulfate phosphor; and a garnet (YAG) phosphor. 
     
     
         9 . The composition of  claim 1 , and further comprising particles of a light reflective material suspended in the liquid binder. 
     
     
         10 . The composition of  claim 9 , wherein the light reflective material is selected from the group consisting of: magnesium oxide, titanium dioxide, barium sulfate and combinations thereof. 
     
     
         11 . The composition of  claim 10 , wherein the light reflective material has a particle size in a range selected from the group consisting of: 0.1 μm to 10 μm and 0.1 μm to 1 μm. 
     
     
         12 . The composition of  claim 10 , wherein a weight percent loading of light reflective material to phosphor material is in a range selected from the group consisting of: 0.01% to 10%; 0.01% to 1%; 0.1% to 1% and 0.5% to 1%. 
     
     
         13 . A photoluminescence wavelength conversion component for a solid-state light emitting device comprising a substrate having deposited on a surface thereof at least one layer of the composition of  claim 1 . 
     
     
         14 . The component of  claim 13 , wherein the composition is provided over an area of at least 0.8 cm 2  to 180 cm 2 . 
     
     
         15 . The component of  claim 13 , wherein the substrate is light transmissive. 
     
     
         16 . The component of  claim 15 , wherein the substrate and binder in a cured state have refractive indices that are within 0.02 of each other. 
     
     
         17 . The component of  claim 15 , wherein the substrate is configured as a light guide and the composition provided on at least a part of a light emitting face of the light guide. 
     
     
         18 . The component of  claim 17 , wherein the substrate is selected from the group consisting of: an acrylic, a polycarbonate, a silicone and a glass. 
     
     
         19 . The component of  claim 13 , wherein substrate comprises a light reflective surface. 
     
     
         20 . The component of  claim 19 , wherein the light reflective surface is selected from the group consisting of: silver, aluminum, chromium, a light reflective polymer, a light reflective paper, a light reflective paint and a light reflective metal. 
     
     
         21 . A photoluminescence wavelength conversion component for a solid-state light emitting device comprising: a substrate having on a surface thereof a layer of a photoluminescent composition that is excitable by blue light of wavelength 380 nm to 480 nm and wherein the composition is deposited on the substrate using a method selected from the group consisting of: screen printing; inkjet printing; letterpress printing, gravure printing; flexograph printing and pad printing. 
     
     
         22 . The component of  claim 21 , wherein the composition comprises a suspension of particles of at least one blue light excitable phosphor material in a light transmissive liquid binder and wherein the weight loading of at least one phosphor material to binder material is in a range 40% to 75%. 
     
     
         23 . The component of  claim 21 , wherein the composition is printed as a first order stochastic pattern comprising a pseudo random array of dots of substantially the same size. 
     
     
         24 . The component of  claim 21 , wherein the composition is printed as a second order stochastic pattern comprising a pseudo random array of dots of varying size. 
     
     
         25 . The component of  claim 21 , wherein the composition is printed as a half tone pattern comprising a regular array of dots of varying size. 
     
     
         26 . The component of  claim 21 , wherein the substrate is light transmissive. 
     
     
         27 . The component of  claim 26 , wherein the substrate is configured as a light guide and the composition provided on at least a part of a light emitting face of the light guide. 
     
     
         28 . The component of  claim 26 , wherein the substrate is selected from the group consisting of: an acrylic, a polycarbonate, a silicone and a glass. 
     
     
         29 . The component of  claim 21 , wherein substrate comprises a light reflective surface. 
     
     
         30 . The component of  claim 29 , wherein the light reflective surface is selected from the group consisting of: silver, aluminum, chromium, a light reflective polymer, a light reflective paper, a light reflective paint and a light reflective metal. 
     
     
         31 . A method of manufacturing a photoluminescence wavelength conversion component for a solid-state light emitting device wherein the component comprises a substrate having a layer of a phosphor material that is excitable by blue light of wavelength 380 nm to 480 nm, the method comprising:
 a) mixing a blue light excitable phosphor material with a light transmissive binder wherein the weight loading of at least one phosphor material to binder material is in a range 40% to 75%;   b) printing the composition as a layer over at least a part of a substrate; and   c) at least partially curing the light transmissive binder.   
     
     
         32 . The method of  claim 31 , wherein the composition is printed using a method selected from the group consisting of: screen printing; inkjet printing; letterpress printing, gravure printing; flexograph printing and pad printing. 
     
     
         33 . The method of  claim 31 , wherein the substrate comprises a thermoplastics material and further comprising heating the substrate and forming the component into a selected shape. 
     
     
         34 . The method of  claim 33 , and further comprising during printing the composition, selectively varying the thickness of the layer such that after forming the component into a selected shape the resulting composition layer is of a substantially uniform thickness. 
     
     
         35 . The method of  claim 33 , wherein the binder has in a cured state an elasticity of 300% to 500%. 
     
     
         36 . A component manufactured according to the method of  claim 31 . 
     
     
         37 . A photoluminescent composition comprising: a suspension of particles of at least one phosphor material in a light transmissive liquid binder wherein the phosphor material is excitable by blue light of wavelength 380 nm to 480 nm and wherein the binder has in a cured state an elasticity of 300% to 500%. 
     
     
         38 . A light emitting device comprising: at least one solid-state light emitter operable to generate blue light of wavelength 380 nm to 480 nm and a component according to  claim 13 . 
     
     
         39 . A photoluminescence light emitting signage surface comprising: a substrate having printed on a surface thereof at least one layer of the composition according to  claim 1 . 
     
     
         40 . The signage surface of  claim 39 , wherein the composition is provided over an area of at least 100 cm 2 . 
     
     
         41 . The signage surface of  claim 39 , wherein the substrate is light transmissive and is selected from the group consisting of: an acrylic, a polycarbonate, a silicone and a glass. 
     
     
         42 . A light emitting sign comprising: at least one solid state light emitter operable to generate blue light of wavelength 380 nm to 480 nm and a signage surface according to  claim 39 .