Phosphor, manufacturing method thereof, and light-emitting device using the phosphor
A red-light emitting phosphor is provided, having a basic composition represented by K a (Si 1-x ,Mn x )F b and also having a particular Raman spectrum, wherein the intensity ratio I 1 /I 0 , which is a ratio of (I 1 ) the peak in a Raman shift of 600±10 cm −1 assigned to Mn—F bonds in the crystal to that (I 0 ) in a Raman shift of 650±10 cm −1 assigned to Si—F bonds in the crystal, is 0.09 to 0.22. This phosphor is produced by bringing a silicon source in contact with an aqueous reaction solution containing potassium permanganate and hydrogen fluoride, wherein a molar ratio of hydrogen fluoride to potassium permanganate is 87 to 127.
1. A phosphor represented by the following formula (I):
K a (Si 1-x ,Mn x )F b ;
wherein a, b and x are numbers satisfying the conditions of 1.5≤a≤2.5, 5.5≤b≤6.5, and 0<x≤0.06 respectively;
wherein the phosphor has a Raman spectrum in which an intensity ratio (I 1 /I 0 ), which is a ratio of the peak intensity (I 1 ) in a Raman shift of 600±10 cm −1 assigned to Mn—F bonds in the crystal to that (I 0 ) in a Raman shift of 650±10 cm −1 assigned to Si—F bonds in the crystal, is 0.09 to 0.17;
wherein the phosphor has an absorptivity (α) in a range of 66% to 83.9%; and
wherein the absorptivity (α) is equal to an external quantum efficiency (η) of the phosphor/an internal quantum efficiency (η′) of the phosphor, wherein the internal quantum efficiency (η′) of the phosphor is represented by formula (II) below, and wherein the external quantum efficiency (η) of the phosphor is represented by formula (III) below,
internal
quantum
efficiency
(
η
′
)
=
∫
λ
·
[
P
(
λ
)
]
d
λ
∫
λ
·
[
E
(
λ
)
-
R
(
λ
)
]
d
λ
(
II
)
external
quantum
efficiency
(
η
)
=
∫
λ
·
[
P
(
λ
)
]
d
λ
∫
λ
·
[
E
(
λ
)
]
d
λ
(
III
)
wherein E(λ) represents a whole spectrum of light emitted by an excitation light source onto the phosphor in terms of the number of photons,
wherein R(λ) represents a spectrum of light emitted by the excitation light source but reflected by the phosphor in terms of the number of photons, and
wherein P(λ) represents an emission spectrum of the phosphor in terms of the number of photons.
2. The phosphor according to claim 1 , having an internal quantum efficiency of 80% or more.
3. The phosphor according to claim 1 , wherein the external quantum efficiency is in a range of 61% to 73%.
4. The phosphor according to claim 1 , wherein the internal quantum efficiency of the phosphor is 85% or more.
5. The phosphor according to claim 1 , wherein the internal quantum efficiency of the phosphor is in a range of 85% to 92%.
6. A method of manufacturing a phosphor, comprising:
immersing a silicon source to react in an aqueous reaction solution containing potassium permanganate and hydrogen fluoride;
wherein a molar ratio of hydrogen fluoride to potassium permanganate in the aqueous reaction solution is 87 to 127; and
wherein a concentration of hydrogen fluoride in the aqueous reaction solution is in a range of 27 to 40 wt %.
7. A light-emitting device comprising:
a light-emitting element radiating light in the wavelength range of 440 to 470 nm; and
a phosphor layer containing the phosphor according to claim 1 .
8. The light-emitting device according to claim 7 , wherein the luminescent layer contains a phosphor having a main emission peak in a wavelength range of 520 to 570 nm.
9. The light-emitting device according to claim 7 , wherein the phosphor layer further contains a green-light emitting phosphor or a yellow-light emitting phosphor.
10. The light-emitting device according to claim 9 , wherein the green-light emitting phosphor or the yellow-light emitting phosphor is selected from the group consisting of (Sr,Ca,Ba) 2 SiO 4 :Eu, Ca 3 (Sc,Mg) 2 Si 3 O 12 :Ce, (Y,Gd) 3 (Al,Ga) 5 O 12 :Ce, (Ca,Sr,Ba)Ga 2 S 4 :Eu, (Ca,Sr,Ba)Si 2 O 2 N 2 :Eu, and (Ca,Sr)-αSiAlON.
11. The light-emitting device according to claim 7 , wherein the phosphor layer further contains an orange-light emitting phosphor or a red-light emitting phosphor.
12. The light-emitting device according to claim 11 , wherein the orange-light emitting phosphor or the red-light emitting phosphor is selected from the group consisting of (Sr,Ca,Ba) 2 SiO 4 :Eu, Li(Eu,Sm)W 2 O 8 , (La,Gd,Y) 2 O 2 S:Eu, (Ca,Sr,Ba)S:Eu, (Sr,Ba,Ca) 2 Si 5 N 8 :Eu, and (Sr,Ca)AlSiN 3 :Eu.