Current display device technology relies on liquid crystal displays (LCDs), which is one of the most widely used flat panel displays for industrial and residential applications. However, next-generation devices that will have low energy consumption, compact size, and high brightness, requiring improved color gamut (NTSC ratio).
LED backlight units (BLU) for use in displays are based on a combination of a blue LED, a green phosphor and a red phosphor. The color gamut of LED BLUs is largely determined by the choice of phosphors. Red phosphor K2SiF6:Mn4+ has a peak with full width at half maximum (FWHM) of 6 to 8 nm yields high color reproducibility in correspondence with the relative intensity of the emission peak. Green phosphor, β-SiAlON: Eu2+ has a half width of 46 to 52 nm and has peak wavelength of 534 nm, which is not a pure green but greenish yellow in color. Accordingly, there is also a need for new green emitting phosphors that efficiently absorb blue radiation, provide high quantum efficiency, and have improved color rendering.
Briefly, in one aspect, the present disclosure relates to a device including an LED light source optically coupled to a phosphor material including a green-emitting phosphor selected from the group consisting of compositions (A1)-(A70) and combinations thereof.
Another aspect is a lighting apparatus including the device. Yet another aspect is a backlight apparatus including the device.
These and other features, aspects, and advantages of the present disclosure will become better understood when the following detailed description is read with reference to the accompanying drawings in which like characters represent like parts throughout the drawings, wherein:
In the following specification and the claims, the singular forms “a”, “an” and “the” include plural referents unless the context clearly dictates otherwise. As used herein, the term “or” is not meant to be exclusive and refers to at least one of the referenced components being present and includes instances in which a combination of the referenced components may be present, unless the context clearly dictates otherwise.
Approximating language, as used herein throughout the specification and claims, may be applied to modify any quantitative representation that could permissibly vary without resulting in a change in the basic function to which it is related. Accordingly, a value modified by a term or terms, such as “about” and “substantially” is not limited to the precise value specified. In some instances, the approximating language may correspond to the precision of an instrument for measuring the value.
Devices according to the present disclosure include an LED light source optically coupled to a phosphor material including a green-emitting phosphor selected from the group consisting of compositions (A1)-(A70) and combinations thereof. Most of these compositions (A1)-(A70) are minerals that may emit green light, and referred to as green-emitting phosphors. In some embodiments, one or more compositions (A1)-(A70) are hydrated. The one or more compositions (A1)-(A70) may vary in the degree of hydration.
The compositions of groups (A1)-(A15) represent formulae, and each formula represents various possible minerals that may be green-emitting phosphors. A formula may include a green-emitting phosphor of respective formula or a combination of possible green-emitting phosphors. The square brackets in formulae (A25), (A60), (A64) and (A66) indicate that at least one of the elements, is present in the phosphor, and any combination of two or more thereof may be present. For example, the formula [K,Ba,Ca]2(UO2)2Si5O13—H2O encompasses at least one of K, Ba, Ca or any combination of two or more of K, Ba, or Ca. Furthermore, some compositions such as (A70) show “U” after the colon “:” in the composition. This representation indicates that the composition is doped with U (uranium) and may be referred to as U-doped phosphor.
In some embodiments, the green-emitting phosphor is selected from the group consisting of compositions of formula (A1). Examples of the green-emitting phosphor of formula (A1) include Na2(UO2)2(AsO4)25H2O, K2(UO2)2(AsO4)2-6H2O, Ba(UO2)2(AsO4)2—(10-12)H2), Co(UO2)2(AsO4)2-8H2O, Cu(UO2)2(AsO4)2-8H2O, Cu(UO2)2(AsO4)2-12H2O, Zn(UO2)2(AsO4)2-10H2O, Mg(UO2)2(AsO4)2-(4-8)H2), Mg(UO2)2(AsO4)2-(10-12)H2), Ca(UO2)2(AsO4)2-8H2), Ca(UO2)2(AsO4)2-10H2), Ba(UO2)2(AsO4)2-8H2), Ba(UO2)2(AsO4)2-(10-12)H2), (NH4,H3O)2(UO2)2(AsO4, PO4)2-6H2), (NH4)2(UO2)2(PO4)2-6H2), (H3O)2(UO2)2(PO4)2-6H2O, Na2(UO2)2(PO4)2-(6-8)H2), Na2(UO2)2(PO4)2-(10-16)H2O, K2(UO2)2(PO4)2-6H2), Fe(UO2)2(PO4)2-8H2), Mg(UO2)2(PO4)2-8H2), Mg(UO2)2(PO4)2-10H2O, Ca(UO2)2(PO4)2-(2-6)H2), Ca(UO2)2(PO4)2-11H2O, Ba(UO2)2(PO4)2-6H2O, Ba(UO2)2(PO4)2-8H2), Ba(UO2)2(PO4)2-12H2O, Pb(UO2)2(PO4)2-4H2O, Na2(UO2)2(VO4)2-6H2), K2(UO2)2(VO4)2-(1-3)H2O, Ca(UO2)2(VO4)2-3H2), or a combination thereof.
In some embodiments, the green-emitting phosphor is selected from the group consisting of compositions of formula (A2). Examples of the green-emitting phosphor of formula (A2) include K(UO2)(SO4)(OH)—H2O, Na(UO2)(SO4)(OH)—2H2O, or a combination thereof. In some embodiments, the green-emitting phosphor is selected from the group consisting of compositions of formula (A3). Examples of the green-emitting phosphor of formula (A3) include K4(UO2)(CO3)3, Na4(UO2)(CO3)3, Na2Ca(UO2)(CO3)3-6H2O, Mg2(UO2)(CO3)3-18H2O, CaMg(UO2)(CO3)3-12H2O, Ca2(UO2)(CO3)3—11H2O, or a combination thereof. In some embodiments, the green-emitting phosphor is selected from the group consisting of compositions of formula (A4). Examples of the green-emitting phosphor of formula (A4) include Ca(UO2)4(AsO4)2(OH)4—6H2O, Pb(UO2)4(PO4)2(OH)4—7H2O, or a combination thereof.
In some embodiments, the green-emitting phosphor is selected from the group consisting of compositions of formula (A5). Examples of the green-emitting phosphor of formula (A5) include K2(UO2)6O4(OH)6-7H2O, Ca(UO2)6O4(OH)6-8H2O, Ba(UO2)6O4(OH)6-8H2O, or a combination thereof. In some embodiments, the green-emitting phosphor is selected from the group consisting of compositions of formula (A6). Examples of the green-emitting phosphor of formula (A6) include (NH4)2(UO2)(SO4)2—2H2O, Na2(UO2)(SO4)2—3H2O, or a combination thereof. In some embodiments, the green-emitting phosphor is selected from the group consisting of compositions of formula (A7). Examples of the green-emitting phosphor of formula (A7) include Al(UO2)2(AsO4)2(F,OH)—6.5H2O, Al(UO2)2(VO4)2(OH)—8H2O, Al(UO2)2(VO4)2(OH)—11H2O, Al(UO2)2(PO4)2(OH)—8H2O, or a combination thereof. In some embodiments, the green-emitting phosphor is selected from the group consisting of compositions of formula (A8). Examples of the green-emitting phosphor of formula (A8) include Co2(UO2)6(SO4)3(OH)10-16H2O, Ni2(UO2)6(SO4)3(OH)10-16H2O, Na4(UO2)6(SO4)3(OH)10-4H2O, or a combination thereof. In some embodiments, the green-emitting phosphor is selected from the group consisting of compositions of formula (A9). Examples of the green-emitting phosphor of formula (A9) include Pb2(UO2)3O2(PO4)2—5H2O, Ca2(UO2)3O2(PO4)2—7H2O, or a combination thereof. In some embodiments, the green-emitting phosphor is selected from the group consisting of compositions of formula (A10). Examples of the green-emitting phosphor of formula (A10) include Ba(UO2)3(SeO3)2O2-3H2O, Na(H3O)(UO2)3(SeO3)2O2-4H2O, or a combination thereof. In some embodiments, the green-emitting phosphor is selected from the group consisting of compositions of formula (A70). In some embodiments, in formula (A70), A is Na, K, or a combination thereof and M is Si, Ti, or a combination thereof. In some embodiments, the phosphor of formula (A70) is K2SiF6:U6+.
Examples of the green-emitting phosphor of formula (A11) include UO3-0.75H2O, UO3—H2O, UO3—2H2O, or a combination thereof. Examples of the green-emitting phosphor of formula (A12) include UO4—2H2O, UO4—4H2O, or a combination thereof. Examples of the green-emitting phosphor of formula (A13) include UO2CO3, UO2CO3—H2O, (UO2)(CO3)—2H2O, or a combination thereof. Examples of the green-emitting phosphor of formula (A14) include U(UO2)3(PO4)2(OH)6-2H2O, U(UO2)3(PO4)2(OH)6—4H2O, or a combination thereof. Examples of the green-emitting phosphor of formula (A15) include Ca(UO2)(CO3)2—3H2O, Ca(UO2)(CO3)2—5H2O, or a combination thereof.
Other examples include, but are not limited to, HAl(UO2)4(AsO4)4—4OH2O, H0.5Al0.5(UO2)2(PO4)2-8H2O, Cu(UO2)2(SO4)2(OH)2-8H2O, K2Ca3[(UO2)(CO3)3]2-7H2O, Na7(UO2)(SO4)4(SO3OH)—3H2O, Ca2Ba4[(UO2)3O2(PO4)2]3-16H2O, NaAl(UO2)2(SO4)4- 18H2O, Na2Mg(UO2)2(SO4)4-18H2), Na7(UO2)(SO4)4Cl—2H2), (K,Na)(UO2)SiO3OH)—1.5H2O, Ca(UO2)2[SiO3(OH)]2-5H2O, Ca(UO2)3(MoO4)3(OH)2-11H2), Al2(UO2)(PO4)2(OH)2-8H2O, Al3(UO2)(PO4)3(OH)2-13H2O, Al(UO2)3(PO4)2(OH)3-5.5H2O, Al2(UO2)3(PO4)2(OH)6-10H2O, Ca(UO2)4(SO4)2(OH)6-6H2O, K(UO2)2(SO4)(OH)3—H2O, H2Pb3(UO2)6O4(PO4)4-12H2O, Na4(UO2)(SO4)3-3H2O, Ca(UO2)3(CO3)2O2-6H2O, Ca[(UO2)2Si5O12(OH)2]—3H2O, (UO2)3(SeO3)2(OH)2-5H2O, (U)2(UO2)4O6(OH)4-9H2O, (UO2)8(SO4)(OH)14-3H2O, (UO2)8(SO4)(OH)10-5H2), Y2U4(CO3)3O12-14.5H2O, Mg(UO2)2(SO4)O2-3.5H2), Pb[(UO2)3O3(OH)2]3H2O, Pb1.5[(UO2)10)O6(OH)11]—11H2), Na5(UO2)(SO4)3(SO3OH)—H2O, Ca(UO2)2Si6O15-5H2O, PbU7O22-12H2), Ca2Cu(UO2)(CO3)4-6H2O, (H3O)3KCa(UO2)7O4(PO44-8H2), (H3O)4Ca2(UO2)2(PO4)4-5H2), Ca3Mg3(UO2)2(CO3)6(OH)4-8H2); HAl(UO2)PO4(OH)3-4H2), [(UO2)8O2(OH)12]—12H2O, NaCa3(UO2)(SO4)(CO3)3F—10H2O, Ca(UO2)6(CO3)5(OH)4-6H2), (UO2)2(SO4)2-5H2O, (H3O)2Mg(UO2)2(SiO4)2-4H2O, (UO2)2SiO4-2H2), (Na,K)(UO2)SiO3(OH)—1.5H2O, (H3O)(UO2)(AsO4)—3H2), (UO2)6(SO4)O2(OH)6-14H2), Al0.5-1(UO2)4(PO4)4-(20-21)H2O(F<1), (Mg,Ca)4(UO2)4(Si2O5)5.5(OH)5-13H2O, Cu(UO2)(OH)4, (K,Ba,Ca)2(UO2)2Si5O13—H2O, K2Ca(UO2)7(PO4)4(OH)6-6H2O, Zn2(UO2)6(SO4)3(OH)10-16H2), CaZn11(UO2)(CO3)3(OH)20-4H2O or a combination thereof.
The green-emitting phosphors disclosed herein may absorb radiation in the near-UV or blue region (a wavelength range between about 400 nm and 470 nm) and emit in a narrow region with an emission peak centered in a wavelength range from about 510 nm to about 540 nm, particularly from about 520 nm to about 530 nm. In some embodiments, these phosphors may be utilized in a phosphor blend to produce white light. These narrow green-emitting phosphors may be useful in display applications, in particular.
In some embodiments, an activator ion may be present in the green emitting phosphor such as Mn2+, Mn4+, Ce3+, Sn2+, Bi3+, Sb3+, Cr3+, Tb3+, Pr3+, Eu3+, Ti4+, In+, Tl+, Dy3+ and Pb2+.
Devices of the present disclosure may be used as lighting and backlight apparatuses for general illumination and display applications. Examples include chromatic lamps, plasma screens, xenon excitation lamps, UV excitation marking systems, automotive headlamps, home and theatre projectors, laser pumped devices, point sensors, liquid crystal display (LCD) backlight units, televisions, computer monitors, mobile phones, smartphone, tablet computers and other handheld devices that have a display including an LED source as described herein. The list of these applications is meant to be merely exemplary and not exhaustive.
The LED light source may be an inorganic LED light source or an organic LED light source. The term ‘LED light source’, as used herein, is meant to encompass all LED light sources such as semiconductor laser diodes (LD), inorganic light emitting diodes, organic light emitting diodes (OLED) or a hybrid of LED and LD. Further, it should be understood that the LED light source may be replaced, supplemented or augmented by another radiation source unless otherwise noted and that any reference to semiconductor, semiconductor LED, or LED chip is merely representative of any appropriate radiation source, including, but not limited to, LDs and OLEDs.
In some embodiments, the phosphor material 14 additionally includes a red emitting phosphor of formula I: A2[MF6]:Mn4+, where A is Li, Na, K, Rb, Cs, or a combination thereof; and M is Si, Ge, Sn, Ti, Zr, Al, Ga, In, Sc, Hf, Y, La, Nb, Ta, Bi, Gd, or a combination thereof. The red emitting phosphor of formula I is optically coupled to the LED light source 12. The phosphors of formula I are described in U.S. Pat. Nos. 7,497,973, and 8,906,724, and related patents assigned to the General Electric Company.
Examples of the red emitting phosphors of formula I include K2[SiF6]:Mn4+, K2[TiF6]:Mn4+, K2[SnF6]:Mn4+, Cs2[TiF6]:Mn4+, Rb2[TiF6]:Mn4+, Cs2[SiF6]:Mn4+, Rb2[SiF6]:Mn4+, Na2[TiF6]:Mn4+, Na2[ZrF6]:Mn4+, K3[ZrF7]:Mn4+, K3[BiF7]:Mn4+, K3[YF7]:Mn4+, K3[LaF7]:Mn4+, K3[GdF7]:Mn4+, K3[NbF7]:Mn4+ or K3[TaF7]:Mn4+. In certain embodiments, the phosphor of formula I is K2SiF6:Mn4+.
The phosphor material 14 may be present in any form such as powder, glass, composite e.g., phosphor-polymer composite or phosphor-glass composite. Further, the phosphor material 14 may be used as a layer, sheet, strip, dispersed particulates, or a combination thereof. In some embodiments, the phosphor material 14 includes the green-emitting phosphor in glass form. In some of these embodiments, the device 10 may include the phosphor material 14 in form of a phosphor wheel (not shown in figures). The phosphor wheel may include the green-emitting phosphor in glass form. A phosphor wheel and related devices are described in a previously filed patent application Serial No. PCT/US17/31654.
In some embodiments, the device 10 may be a backlight unit for display applications. In these embodiments, the phosphor material 14 including the green-emitting phosphor, may be present in form of a sheet or strip that is mounted or disposed on a surface of the LED light source 12. A backlight unit and related devices are described in a previously filed patent application Ser. No. 15/370762.
The LED chip 22 may be encapsulated within an envelope 28. The envelope 28 may be formed of, for example glass or plastic. The LED chip 22 may be enclosed by an encapsulant material 32. The encapsulant material 32 may be a low temperature glass, or a polymer or resin known in the art, for example, an epoxy, silicone, epoxy-silicone, acrylate or a combination thereof. In an alternative embodiment, the lighting apparatus 100 may only include the encapsulant material 32 without the envelope 28. Both the envelope 28 and the encapsulant material 32 should be transparent to allow light to be transmitted through those elements.
With continued reference to
In some other embodiments, the phosphor material including green-emitting phosphor as described herein is interspersed within the encapsulant material 32, instead of being disposed directly on the LED chip 22 as shown in
In some other embodiments, a layer 36 of the phosphor material including the green-emitting phosphor, is coated onto a surface of the envelope 28 as illustrated in
In any or all the above configurations, the lighting apparatus 100, 200, or 300 shown respectively in
Some embodiments are directed to a backlight apparatus 50 as illustrated in
In addition to the green-emitting phosphor and, optionally, the red-emitting Mn4+ doped phosphor of formula I, the phosphor material may further include one or more other luminescent materials. Additional luminescent materials such as blue, yellow, red, orange, or other color phosphors may be used in the phosphor material to customize the white color of the resulting light and produce specific spectral power distributions.
Suitable additional phosphors for use in the phosphor material include, but are not limited to:
((Sr1−z (Ca, Ba, Mg, Zn)z)1−(x+w)(Li, Na, K, Rb)wCex)3(Al1−ySiy)O4+y+3(x−w)F1−y−3(x−w), 0<x≤0.10, 0≤y≤0.5, 0≤z≤0.5, 0≤w≤x; (Ca, Ce)3Sc2Si3O12(CaSiG); (Sr,Ca,Ba)3Al1−xSixO4+xF1−x:Ce3+ (SASOF)); (Ba,Sr,Ca)5(PO4)3(Cl,F,Br,OH):Eu2+,Mn2+; (Ba,Sr,Ca)BPO5:Eu2+,Mn2+; (Sr,Ca)10(PO4)6*vB2O3:Eu2+ (wherein 0<v≤1); Sr2Si3O8*2SrCl2:Eu2+; (Ca,Sr,Ba)3MgSi2O8:Eu2+,Mn2+;BaAl8O13:Eu2+; 2SrO*0.84P2O5*0.16B2O3:Eu2+; (Ba,Sr,Ca)MgAl10O17:Eu2+,Mn2+; (Ba,Sr,Ca)Al2O4:Eu2+; (Y,Gd,Lu,Sc,La)BO3:Ce3+,Tb3+; ZnS:Cu+,Cl−; ZnS:Cu+,Al3+; ZnS:Ag+,Cl−; ZnS:Ag+,Al3+; (Ba,Sr,Ca)2Si1−nO4−2n: Eu2+ (wherein 0≤n≤0.2); (Ba,Sr,Ca)2(Mg,Zn)Si2O7:Eu2+; (Sr,Ca,Ba)(Al,Ga,In)2S4:Eu2+; (Y,Gd,Tb,La,Sm,Pr,Lu)3(Al,Ga)5−aO12−3/2a:Ce3+ (wherein 0≤a≤0.5); (Ca,Sr)8(Mg,Zn)(SiO4)4Cl2:Eu2+,Mn2+; Na2Gd2B2O7:Ce3+,Tb3+; (Sr,Ca,Ba,Mg,Zn)2P2O7:Eu2+,Mn2+; (Gd,Y,Lu,La)2O3:Eu3+,Bi3+; (Gd,Y,Lu,La)2O2S:Eu3+,Bi3+; (Gd,Y,Lu,La)VO4:Eu3+,Bi3+; (Ca,Sr)S:Eu2+,Ce3+; SrY2S4:Eu2+; CaLa2S4:Ce3+; (Ba,Sr,Ca)MgP2O7:Eu2+,Mn2+; (Y,Lu)2WO6:Eu3+,Mo6+; (Ba,Sr,Ca)bSigNm:Eu2+ (wherein 2b+4g=3m); Ca3(SiO4)Cl2:Eu2+; (Lu,Sc,Y,Tb)2-u-vCevCa1+uLiwMg2−wPw(Si,Ge)3−wO12−u/2 (where −0.5≤u≤1, 0<v≤0.1, and 0≤w≤0.2); (Y,Lu,Gd)2−m (Y,Lu,Gd)CamSi4N6+mC1−m:Ce3+, (wherein (Lu,Ca,Li,Mg,Y), alpha-SiAlON doped with Eu2+ and/or Ce3+; Sr(LiAl3N4):Eu2+, (Ca,Sr,Ba)SiO2N2:Eu2+,Ce3+; beta-SiAlON:Eu2+, 3.5MgO*0.5MgF2*GeO2:Mn4+; Ca1−c−CecEufAl1+cSi1−cN3, (where 0≤c≤0.2, 0≤f≤0.2); Ca1−h−rCehEurAl1−h (Mg,Zn)hSiN3, (where 0≤h≤0.2, 0≤r≤0.2); Ca1−2s−tCe5(Li,Na)sEutAlSiN3, (where 0≤s≤0.2, 0≤t≤0.2, s+t>0); (Sr, Ca)AlSiN3: Eu2+,Ce3+, and Li2CaSiO4:Eu2+.
The ratio of each of the individual phosphors in the phosphor material may vary depending on the characteristics of the desired light output. The relative proportions of the individual phosphors in the various phosphor materials may be adjusted such that when their emissions are blended and employed in a device, for example a lighting apparatus, there is produced visible light of predetermined x and y values on the CIE chromaticity diagram.
Other additional luminescent materials suitable for use in the phosphor material may include electroluminescent polymers such as polyfluorenes, preferably poly(9,9-dioctyl fluorene) and copolymers thereof, such as poly(9,9′-dioctylfluorene-co-bis-N, N′-(4-butylphenyl)diphenylamine) (F8-TFB); poly(vinylcarbazole) and polyphenylenevinylene and their derivatives. In addition, the light emitting layer may include a blue, yellow, orange, green or red phosphorescent dye or metal complex, a quantum dot material, or a combination thereof. Materials suitable for use as the phosphorescent dye include, but are not limited to, tris(1-phenylisoquinoline) iridium (III) (red dye), tris(2-phenylpyridine) iridium (green dye) and Iridium (III) bis(2-(4,6-difluorephenyl)pyridinato-N,C2) (blue dye). Commercially available fluorescent and phosphorescent metal complexes from ADS (American Dyes Source, Inc.) may also be used. ADS green dyes include ADS060GE, ADS061GE, ADS063GE, and ADS066GE, ADS078GE, and ADS090GE. ADS blue dyes include ADS064BE, ADS065BE, and ADS070BE. ADS red dyes include ADS067RE, ADS068RE, ADS069RE, ADS075RE, ADS076RE, ADS067RE, and ADS077RE. Exemplary quantum dot materials are based on CdSe, ZnS or InP, including, but not limited to, core/shell luminescent nanocrystals such as CdSe/ZnS, InP/ZnS, PbSe/PbS, CdSe/CdS, CdTe/CdS or CdTe/ZnS. Other examples of the quantum dot materials include perovskite quantum dots such as CsPbX3, where X is Cl, Br, I or a combination thereof.
By use of the embodiments described in the present disclosure, particularly the phosphor materials described herein, devices can be provided producing white light for display applications for example LCD backlight units, having high color gamut and high luminosity. Alternately, by use of the embodiments described in the present disclosure, particularly the phosphor materials described herein, devices can be provided producing white light for general illumination having high luminosity and high CRI values for a wide range of color temperatures of interest (2500 K to 10000 K).
While only certain features of the disclosure have been illustrated and described herein, many modifications and changes will occur to those skilled in the art. It is, therefore, to be understood that the appended claims are intended to cover all such modifications and changes as fall within the true spirit of the disclosure.
This application relates to, and claims priority from a provisional U.S. patent application having docket number 323772-1 and Ser. No. 62/640,150, entitled “DEVICES INCLUDING GREEN-EMITTING PHOSPHORS”, filed on Mar. 8, 2018, which application is hereby incorporated by reference.
Number | Date | Country | |
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62640150 | Mar 2018 | US |