High luminous efficacy phosphor converted white LEDs
A white light emitting device comprises: an LED that generates excitation light of wavelength from 420 nm to 480 nm; and photoluminescence materials that generate light with a peak emission wavelength from 500 nm to 650 nm comprising a broadband phosphor, and a manganese-activated narrowband red fluoride phosphor with a peak emission wavelength from 628 nm to 640 nm and a full width at half maximum of less than 30 nm. The device generates white light with a selected color temperature from 2200K to 6500K, a General Color Rendering Index, CRI Ra, of at least 80, and a Duv (Delta u, v) from 0.0060 to 0.0170 for the selected color temperature and wherein the device has an LER (Luminous Efficacy of Radiation) of at least 320 lm/W opt .
1 . A white light emitting device comprising:
an LED for generating excitation light of wavelength from 420 nm to 480 nm; and
photoluminescence materials for generating light with a peak emission wavelength from 500 nm to 650 nm comprising a broadband phosphor, and a manganese-activated narrowband red fluoride phosphor with a peak emission wavelength from 628 nm to 640 nm and a full width at half maximum of less than 30 nm;
wherein the device is for generating white light with a selected color temperature from 2200K to 6500K, a General Color Rendering Index, CRI Ra, of at least 80, and a CIE 1976 Duv from 0.0060 to 0.0170 for the selected color temperature; and
wherein the device has an LER (Luminous Efficacy of Radiation) of at least 320 lm/W opt .
2 . The white light emitting device of claim 1 wherein:
when the selected color temperature is about 2700K, the device has an LER of at least 360 lm/W opt ;
when the selected color temperature is about 3000K, the device has an LER of at least 355 lm/W opt ,
when the selected color temperature is about 4000K, the device has an LER of at least 350 lm/W opt ; and
when the selected color temperature is about 6500K, the device has an LER of at least 320 lm/W opt .
3 . The white light emitting device of claim 1 , wherein the device is for generating white light with a CRI R8 of at least 72.
4 . The white light emitting device of claim 1 , comprising a single-layer photoluminescence structure comprising a photoluminescence layer covering the LED and comprising the broadband phosphor and the manganese-activated narrowband red fluoride phosphor.
5 . The white light emitting device of claim 1 , comprising a double-layer photoluminescence structure comprising:
a first photoluminescence layer covering a light emitting face the LED and consisting of the manganese-activated narrowband red fluoride phosphor; and
a second photoluminescence layer comprising the broadband phosphor, wherein the second photoluminescence layer encapsulates the first photoluminescence layer.
6 . The white light emitting device of claim 1 , wherein the LED is operated at a current density from 20 mA/mm 2 to 120 mA/mm 2 .
7 . The white light emitting device of claim 1 , wherein the manganese-activated narrowband red fluoride phosphor comprises at least one of: K 2 SiF 6 :Mn 4+ , K 2 TiF 6 :Mn 4+ , and K 2 GeF 6 :Mn 4+ .
8 . The white light emitting device of claim 1 , wherein the broadband phosphor comprises at least one of:
a broadband green to yellow phosphor comprising an yttrium aluminum garnet phosphor or a lutetium aluminum garnet phosphor, and
a broadband orange to red phosphor comprising a calcium aluminum silicon nitride phosphor.
9 . A white light emitting device comprising:
an LED for generating excitation light of wavelength from 420 nm to 480 nm; and
photoluminescence materials for generating light with a peak emission wavelength from 500 nm to 650 nm comprising a broadband phosphor, and a manganese-activated narrowband red fluoride phosphor with a peak emission wavelength from 628 nm to 640 nm and a full width at half maximum of less than 30 nm;
wherein the device is for generating white light with a selected color temperature from 2200K to 6500K, a General Color Rendering Index, CRI Ra, of at least 80, and a CIE 1976 Duv from 0.0060 to 0.0170 for a selected color temperature; and
wherein the device has an OLE (Overall Luminous Efficacy) of at least 210 lm/W dc .
10 . The white light emitting device of claim 9 , wherein:
when the selected color temperature is about 2700K, the device has an OLE of at least 210 lm/W dc ;
when the selected color temperature is about 3000K, the device has an OLE of at least 220 lm/W dc ;
when the selected color temperature is about 4000K, the device has an OLE of at least 225 lm/W dc ; and
when the selected color temperature is about 6500K, the device has an OLE of at least 220 lm/W dc .
11 . The white light emitting device of claim 9 , wherein the device is for generating white light with a CRI R8 of at least 72.
12 . The white light emitting device of claim 9 , comprising a single-layer photoluminescence structure comprising a photoluminescence layer covering the LED and comprising the broadband phosphor and the manganese-activated narrowband red fluoride phosphor.
13 . The white light emitting device of claim 9 , comprising a double-layer photoluminescence structure comprising:
a first photoluminescence layer covering a light emitting face the LED and consisting of the manganese-activated narrowband red fluoride phosphor; and
a second photoluminescence layer comprising the broadband phosphor, wherein the second photoluminescence layer encapsulates the first photoluminescence layer.
14 . The white light emitting device of claim 9 , wherein the LED is operated at a current density from 20 mA/mm 2 to 90 mA/mm 2 .
15 . The white light emitting device of claim 9 , wherein the manganese-activated narrowband red fluoride phosphor comprises at least one of: K 2 SiF 6 :Mn 4+ , K 2 TiF 6 :Mn 4+ , and K 2 GeF 6 :Mn 4+ .
16 . The white light emitting device of claim 9 , wherein the broadband phosphor comprises at least one of:
a broadband green to yellow phosphor comprising an yttrium aluminum garnet phosphor or a lutetium aluminum garnet phosphor, and
a broadband orange to red phosphor comprising a calcium aluminum silicon nitride phosphor.
17 . An LED-filament comprising:
an at least partially light transmissive substrate having a front face;
a linear array of LED chips on the front face of the substrate for generating excitation light of wavelength from 420 nm to 480 nm; and
photoluminescence materials for generating light with a peak emission wavelength from 500 nm to 650 nm comprising a broadband phosphor, and a manganese-activated narrowband red fluoride phosphor with a peak emission wavelength from 628 nm to 640 nm and a full width at half maximum of less than 30 nm;
wherein the LED-filament is for generating white light with a selected color temperature from 2200K to 6500K, a General Color Rendering Index, CRI Ra, of at least 80, and a CIE 1976 Duv from 0.0060 to 0.0170 for the selected color temperature and wherein the device has an OLE (Overall Luminous Efficacy) of at least 210 lm/W dc .
18 . The LED-filament of claim 17 , wherein:
when the selected color temperature is about 2700K, the LED-filament has an OLE of at least 210 lm/W dc ;
when the selected color temperature is about 3000K, the LED-filament has an OLE of at least 220 lm/W dc ;
when the selected color temperature is about 4000K, the LED-filament has an OLE of at least 225 lm/W dc ; and
when the selected color temperature is about 6500K, the LED-filament has an OLE of at least 220 lm/W dc .
19 . The LED-filament of claim 17 , comprising a double-layer photoluminescence structure comprising on the front face of the substrate, the double-layer photoluminescence structure comprising:
a first photoluminescence layer consisting of the manganese-activated narrowband red fluoride phosphor, wherein the first photoluminescence layer is a continuous unbroken elongate strip that encapsulates every LED chip on the substrate; and
a second photoluminescence layer comprising the broadband phosphor, wherein the second photoluminescence layer is a continuous unbroken elongate strip that encapsulates the first photoluminescence layer.