Int
ern
at
i
onal
Journ
al of Ele
ctrical
an
d
Co
mput
er
En
gin
eeri
ng
(IJ
E
C
E)
Vo
l.
10
,
N
o.
4
,
A
ugus
t
2020
,
pp.
3501
~
35
07
IS
S
N:
20
88
-
8708
,
DOI: 10
.11
591/
ijece
.
v
10
i
4
.
pp3501
-
35
07
3501
Journ
al h
om
e
page
:
http:
//
ij
ece.i
aesc
or
e.c
om/i
nd
ex
.ph
p/IJ
ECE
Enh
ancing the
CRI
and lu
men ou
tpu
t for the
6600 K
WL
E
D
with con
vex
-
du
al
-
layer
remote ph
osphor
geom
etry
by apply
ing
red
-
emit
ting M
GS
R
3
SI
2
O
8
:EU
2+
,
MN
2+
ph
osphor
Thuc
Minh B
ui
1
, Nguyen T
hi
Phu
ong L
oan
2
, P
h
an
X
u
an Le
3
, Ng
u
ye
n
Doan Q
uo
c
Anh
4
,
An
h
Tuan Le
5
, Le
Va
n
Th
o
6
1
Facul
t
y
of Elect
ric
a
l
and
E
lectr
o
nic
s E
ng
ine
er
ing
,
Nha
Tra
ng
Uni
ver
sit
y
,
Vie
tna
m
2
Facul
t
y
of
Fund
amenta
l
2,
Pos
ts a
nd
T
el
e
comm
unic
a
ti
ons Insti
tute
of Te
chnol
og
y
,
Viet
n
am
3
Facul
t
y
of Elect
ric
a
l
and
E
lectr
o
nic
s E
ng
ine
er
ing
,
HCM
C
Univer
sit
y
of
Food Ind
ustr
y
,
Vie
tna
m
4
,5
Facul
t
y
of Electrical a
nd
Elec
t
ronic
s E
ng
ineeri
ng,
Ton
Duc
Th
ang
Univer
si
t
y
,
Viet
nam
6
Instit
ute of Tro
pic
a
l
Bio
log
y
,
Viet
n
am Aca
dem
y
of
Sci
ence and Tec
hno
log
y
,
Vie
tna
m
Art
ic
le
In
f
o
ABSTR
A
CT
Art
ic
le
history:
Re
cei
ved
Oct
2
, 2
019
Re
vised
Jan
18
,
20
20
Accepte
d
Fe
b 2
, 2
020
The
tra
d
it
ion
al
white
LE
D
produc
t
esta
bl
ished
with
a
single
chip
and
a
single
phosphor
result
s
in
a
low
col
or
ren
der
ing
ind
ex
(CRI).
The
upgra
de
of
LE
D
pac
kag
e
is
comprised
of
two
c
hips
and
one
p
hosphor
m
at
eri
a
l
and
give
s
the
highe
r
CRI
while
kee
p
ing
high
luminous
eff
ic
i
ency
.
B
ase
d
on
pre
vious
findi
ngs,
th
e
res
ea
rch
p
ape
r
p
erf
orm
s
the
appl
icati
on
of
th
e
two
chi
ps
and
two
phosphors
to
enha
n
ce
the
col
or
tun
abi
l
ity
of
LE
Ds
wit
h
diffe
ren
t
amounts a
nd
intensiti
es
of
th
e
tw
o
emplo
y
ed
pho
sphors
.
Additi
onal
l
y
,
a
c
o
lor
design
m
odel
is bui
lt
to
serv
e
th
e
purpose
of
b
et
t
e
ring
the c
o
lor
fin
e
-
tuni
ng
o
f
the
white
-
li
ght
LE
D
m
odule
.
T
he
m
axi
m
um
va
lue
of
the
d
iffe
r
enc
e
b
et
we
e
n
the
m
ea
sured
CIE
1931
col
or
co
ordina
t
es
and
tha
t
of
the
sim
ula
t
ed
m
odel
is
appr
oximatel
y
0.
0063
ar
ound
the
6600
K
co
rre
lated
co
lor
t
empera
ture
(CCT).
From
the
result
s,
th
is
stud
y
offe
rs
a
quic
k
appr
oa
c
h
to
ac
hi
ev
e
the
col
o
r
fine
t
uning
of
a
whit
e
-
li
ght
LE
D
m
odule
with
a
h
ig
h
CRI
and
luminous
eff
icie
nc
y
.
Ke
yw
or
d
s
:
Color re
nderin
g
in
de
x
Du
al
-
la
ye
r
rem
ote ph
osphor
geo
m
et
ry
MgSr
3
Si
2
O
8
:Eu
2+,
Mn
2+
Mie
-
scat
te
ring
WLE
Ds
Copyright
©
202
0
Instit
ut
e
o
f Ad
vanc
ed
Engi
n
ee
r
ing
and
S
cienc
e
.
Al
l
rights re
serv
ed
.
Corres
pond
in
g
Aut
h
or
:
Anh Tua
n
Le
Faculty
of Elec
tric
al
an
d El
ect
ronics E
nginee
rin
g,
To
n Du
c
Th
a
ng
Un
i
ver
sit
y,
No.
19 Ng
uyen
Huu T
ho Stree
t, Tan
P
hong
Ward,
D
ist
rict
7,
H
o
Chi
Mi
nh Ci
ty
, V
ie
tna
m
.
Em
a
il
: l
eanh
tuan1@tdt
u.
e
du.
vn
1.
INTROD
U
CTION
W
it
h
ou
tst
a
nding
pro
per
ti
es
of
lo
ng
li
fes
pan,
high
reli
abili
ty
and
e
ndura
nce,
ec
o
-
f
rien
dly
an
d
powe
r
-
sa
ving
char
act
e
risti
cs,
an
d
sm
al
l
siz
e
,
w
hite
li
gh
t
-
e
m
itti
ng
di
od
e
s
(LE
Ds)
ha
ve
a
w
or
ld
wide
usa
ge
i
n
il
lu
m
inati
ng
ap
plica
ti
on
s,
pa
rt
ic
ularly
in
as
pe
ct
s
of
a
uto
m
a
ti
c,
bill
bo
a
rd,
a
nd
lo
w
-
te
m
perat
ur
e
li
ghti
ngs
[1
-
3]
.
Rem
ark
ably
,
t
heir
recent
a
dv
ances
i
n
fa
st
s
witc
hing
pro
pe
rtie
s
ha
ve
go
t
them
widely
us
ed
i
n
sm
art
lig
htin
g
wh
ic
h
is
ano
t
he
r
auto
c
on
t
ro
l t
echnolo
gy.
I
n
fact,
there h
av
e
been
a
va
riet
y
of
m
e
tho
ds
t
hat
com
bin
e
the
LED
chips
an
d
the
phospho
r
to
at
ta
in
wh
it
e
li
gh
t
.
The
ve
ry
first
and
chea
pest
pa
cka
ge
ap
plyi
ng
that
com
bina
ti
on
consi
sts
of
a
s
ing
le
blu
e
chi
p
a
nd
a
si
ng
le
ye
ll
ow
phosp
hor,
but
the
re
su
lt
ed
CR
I
is
ver
y
l
ow.
T
he
refor
e
,
fo
c
us
in
g
on
im
pro
ving
the
CR
I,
the
pac
kage
was
bu
il
t
with
the
par
ti
ci
pat
ion
of
a
red
an
d
a
blu
e
chi
p
as
well
as
a
si
ng
le
la
ye
r
of
ye
ll
ow
ph
os
ph
or.
T
he
c
ol
or
re
nd
e
rin
g
i
nd
e
x
CR
I
is
a
qu
a
ntit
at
ive
m
easur
e
of
li
gh
t
qu
al
it
y
com
par
ed
to
t
he
nat
ur
al
li
ght
or
blac
k
-
body
r
adiat
io
n.
Th
us
,
wh
e
n
CR
I
has
a
hig
h
value
t
his
m
eans
the
app
li
ed
phos
ph
or
has
a
broa
d
em
issi
on
sp
ect
r
um
wh
ic
h
helps
to
bette
r
the
li
gh
t
qual
it
y
fo
r
LE
Ds
li
gh
t,
si
m
il
ar
to
the
con
ti
nuous
s
pectr
um
o
f
the
black
-
body
rad
ia
ti
on
[
4
-
6].
W
it
h
the
goal
of
c
us
tom
iz
ing
the
chrom
at
ici
ty
and
CR
I
fo
r
LE
D
lam
ps
,
m
any
rep
or
ts
with
the
top
ic
s
of
c
om
bi
ning
phosp
hor
s
with
Evaluation Warning : The document was created with Spire.PDF for Python.
IS
S
N
:
2088
-
8708
In
t J
Elec
&
C
om
p
En
g,
V
ol.
10
, No
.
4
,
A
ugus
t
2020
:
3501
-
3507
3502
LED
c
h
ips
t
o
accom
plish
the
op
ti
m
iz
ation
and
predict
io
n
of
the
sp
ect
ru
m
hav
e
bee
n
gi
ve
n.
S
peci
fical
ly
,
these
repo
rts
fo
c
us
on
the
app
li
cat
io
n
of
the
e
m
pirical
and
m
at
he
m
a
ti
cal
m
od
el
s
fo
r
the
a
naly
sis
and
deco
m
po
sit
io
n
o
f
the
s
pectrum
of
LED
chi
p
[
7
-
10
]
.
Nev
e
rthe
le
ss,
c
on
st
r
ucting
a
wh
it
e
LED
pac
ka
ge
with
tun
a
ble
c
orrelat
ed
c
olo
r
te
m
per
at
ur
e
s
(CCTs
),
high
ef
fici
en
cy
,
an
d
superi
or
CR
I
is
a
real
chall
eng
in
g
ta
sk
to
acco
m
plish
[
11,
12]
.
P
rev
i
ously
,
the
str
uc
ture
of
a
blu
e
chip
com
bin
e
d
with
tw
o
ph
os
ph
or
m
at
eria
ls
was
app
li
ed
to
rea
ch
a
hi
gh
val
ue
of
CR
I,
bu
t
the
ef
ficacy
is
poor
be
ca
us
e
of
the
Sto
kes
sh
ift
[
13
-
16]
.
The
n,
the
i
m
ple
m
ent
of
the
t
wo
red
and
blu
e
c
hip
s
tog
et
he
r
with
on
e
phosp
hor
r
esulte
d
in
a
n
increase
i
n
CR
I
an
d
eff
ic
acy
but
w
as
un
a
ble
to
tu
ne
the
col
or,
in
com
par
iso
n
with
the
str
uct
ur
e
c
onsist
ing
of
tw
o
phosphors
.
For
tho
se
dr
a
w
bac
ks
,
a
nother
w
hi
te
LED
pac
ka
ge
com
pr
ise
d
of
t
he
tw
o
dif
f
eren
t
LE
D
c
hip
s
an
d
tw
o
phos
ph
ors
has
be
en
pro
posed
to
ac
hieve
high
CR
I
a
nd
l
um
ino
us
o
ut
put
as
well
as
be
able
to
kee
p
a
t
un
a
ble
col
or.
I
n
this
arti
cl
e,
we
sugg
e
st
a
c
olo
r
struct
ur
e
that
is
desi
gn
e
d
base
d
on
Be
er’
s
la
w
a
nd
li
near
co
nversi
on
f
or
the
dem
and
of
pro
du
ci
ng
w
hite
LED
s
wit
h
s
ub
tl
e
c
olor
difference
[
17
-
21
]
.
I
n
a
dd
it
io
n,
this
W
-
LE
D
m
odule
was
m
anu
factu
red
by
app
ly
in
g
yt
trium
al
u
m
inu
m
gar
net
(
YAG)
a
nd
nitr
ide
-
based
phospho
rs
in
blu
e
a
nd
r
ed
LEDs
with
high
CR
I
a
nd
l
um
ino
us
e
ff
ic
ie
ncy.
F
or
t
he
WLE
D
produc
ti
on
,
t
he
ph
os
phors
that
a
re
m
ixed
in
sil
ic
on
e
gl
ues
with
dif
fer
e
nt
pr
op
or
ti
ons
and
de
ns
it
ie
s
are
com
bin
ed
w
it
h
the
r
e
d
a
nd
blu
e
L
ED
chips
.
Fr
om
the r
e
su
lt
s of the
artic
le
,
it
is possible t
o
c
onstruct a
nd
apply
this
pro
po
s
ed
co
l
or
de
sign m
od
el
easil
y.
2.
PREP
ARATI
ON A
ND SI
M
ULATIO
N
2.1.
Prepar
at
i
on
Mg
8
Ge
2
O
11
F
2
:
Mn
4+
is
a
c
ompo
sit
io
n
of
the
f
our
oth
e
r
c
hem
ic
al
m
a
te
rial
s,
inclu
ding
MgO,
Mg
F
2
,
MgCO
3
,
GeO
2
with
the
m
ole
and
w
ei
gh
t
ex
pr
e
ss
ed
in
Ta
ble
1
.
T
he
pre
par
at
io
n
pr
oc
ess
of
MgSr
3
Si
2
O
8
:Eu
2+
,Mn
2+
incl
ud
e
s
tw
o
m
ai
n
sta
ges
of
firin
g
that
need
to
be
f
o
ll
owed
in
a
stric
t
orde
r
to
get
the
best
final
com
po
sit
ion
f
or
t
he
resea
rc
h.
Be
f
ore
the
first
firi
ng,
f
our
a
forem
entioned
m
at
erial
s
m
us
t
be
m
ixed
by
ball
-
m
illi
ng
.
T
hen,
the
at
ta
in
m
ixt
ur
e
is
fire
d
in
capp
e
d
qu
a
rtz
tub
es
in
with
a
ir
at
1200
0
C
w
it
hi
n
two
ho
ur
s
.
Ne
xt,
the
fr
ie
d
m
at
erial
will
be
pow
der
iz
e
d
by
us
in
g
dr
y
ball
-
m
i
ll
ing
m
et
ho
d.
Finall
y,
the
pow
der
go
e
s
thr
ough
the
seco
nd
firi
ng
i
n
open
quartz
bo
at
s
ov
e
rn
i
gh
t
f
or
a
bo
ut
16
hours
at
1200
0
C.
T
he
at
ta
in
pro
du
ct
has
de
ep
r
ed
em
issi
on
c
olor
with
th
e
em
issi
on
pea
k
of
1.8
8
e
V
a
nd
the
e
xcita
ti
on
ef
fici
ency
of
ove
r
3.40 eV
, whic
h i
s b
e
nef
ic
ia
l e
nough t
o be a
ppli
ed
in
the
sim
ula
ti
on
pr
oce
ss.
Table
1.
T
he
in
gr
e
dients
of M
g
8
Ge
2
O
11
F
2
:Mn
4+
com
po
sit
io
n
Ing
redien
t
Mole %
By
weig
h
t
(g)
MgO
700
282
MgF
2
100
62
MgC
O
3
8
9
.2
GeO
2
192
201
2.2.
Simul
at
i
on
The
a
ppli
cat
ion
s
of
the
Lig
ht
To
ols
pro
gr
a
m
and
Mi
e
-
the
or
y
play
a
c
r
uc
ia
l
ro
le
i
n
ca
rry
ing
out
this
work,
as
it
is
easi
er
to
sim
ulate
the
dual
-
la
ye
r
phosp
hor
str
uct
ur
e
of
W
LE
D,
base
d
on
the
a
nal
ysi
s
of
phospho
r
scat
te
rin
g
phe
no
m
enon
a
nd
the
in
vestigat
io
n
in
t
he
im
pacts
of
MgSr
3
Si
2
O
8
:Eu
2+
,Mn
2+
phospho
r
on
the
WLE
Ds’
perform
ance
at
the
6600
K
correla
te
d
te
m
per
at
ur
e.
Be
f
ore
str
uctu
rin
g
the
in
-
cu
p
ph
os
ph
or
config
ur
at
io
n
of
WLE
Ds
,
it
is
necessa
ry
to
pr
e
par
e
the
require
d
phospho
r
la
ye
r
by
m
ixing
the
ch
e
m
ic
al
com
po
undi
ng
of
t
he
Mg
Sr
3
Si
2
O
8
:Eu
2+
,Mn
2+
p
hosph
or
a
nd
t
he
ye
ll
ow
YAG:C
e
3+
w
it
h
the
sil
ic
on
glu
e
,
as
dem
on
strat
e
d
in
Fi
gure
1.
The
sim
ulate
d
m
od
el
of
WLE
Ds
incl
ud
es
t
he
fo
ll
owin
g
c
onsti
tuents:
nin
e
blu
e
chips
,
a
ref
le
ct
or
c
up,
a
phospho
r
la
ye
r,
an
d
a
sil
ic
on
e
la
ye
r.
A
dd
it
io
na
ll
y,
the
par
am
et
ers
of
eac
h
pa
rt
are
expresse
d
as
fo
ll
ow
s.
-
A
r
eflect
or
with
2.07 m
m
d
epth,
8
m
m
b
otto
m
le
ng
th a
nd
9.8
5
m
m
top
len
gth
is
att
ached
to the blue
c
hip
s
-
Each
blu
e
ch
i
p i
s d
esi
gn
e
d wi
th 1.16
W ra
diant po
wer an
d 453 nm
p
eak
w
avelen
gth
-
The
re
fr
act
ive
ind
e
xes
of
p
hosp
ho
r
pa
rtic
le
s
MgSr
3
Si
2
O
8
:E
u
2+
,Mn
2+
a
nd
YAG:
Ce
3+
are
set
at
1.
85
a
nd
1.83 res
pecti
ve
ly
Be
sides,
i
n
te
rm
s
of
m
a
intai
nin
g
the
ACCTs
(a
ve
rag
e
co
rr
el
at
ed
c
olor
te
m
per
at
ur
es)
,
the
con
ce
ntrati
on
of
Y
A
G:
Ce
3+
need
s
to
be
adjusted
a
ppr
opriat
el
y
to
the
change
of
MgSr
3
Si
2
O
8
:Eu
2+
,Mn
2+
con
ce
ntrati
on.
Evaluation Warning : The document was created with Spire.PDF for Python.
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om
p
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20
88
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En
hancin
g
t
he
CRI
and
l
um
e
n o
utput f
or t
he 660
0
K
W
LE
D
wi
th convex
-
du
al
-
layer
…
(
Thuc Mi
nh Bu
i
)
3503
(a)
(b)
(c)
(d)
Figure
1. Illust
rati
on of
WLE
Ds
str
uct
ur
e:
(
a)
3D
m
od
el
li
ng
, (
b)
bondin
g diag
ram
,
(c)
il
lustrati
on
of p
c
-
WLEDs
m
od
el
, (
d)
sim
u
la
ti
on
of
WL
EDs usin
g
li
ghtt
oo
ls c
omm
ercial
so
ftwa
re
3.
RESU
LT
S
A
ND
DI
SCUS
S
ION
As
ca
n
be
seen
from
Figure
2,
t
he
cha
ng
e
in
the
c
on
ce
nt
rati
on
of
re
d
phospho
r
MgSr
3
Si
2
O
8
:Eu
2+
,Mn
2+
is
opposit
e
to
tha
t
of
the
Y
A
G:Ce
3+
ye
ll
ow
phosp
hor.
T
his
opposit
e
change
dem
on
strat
es
t
wo
aspects
,
th
e
first
on
e
is
t
o
m
ai
ntain
the
ACCTs
a
nd
t
he
sec
ond
one
is
it
s
influ
e
nc
e
in
the
scat
te
rin
g
a
nd
a
bs
orpti
on
processes
of
phosp
hor
la
ye
r
s
inside
the
WL
EDs,
w
hich
does
ha
ve
a
gr
eat
effe
ct
on
t
he
c
olo
r
qual
it
y
and
lum
en
outp
ut
of
WLE
Ds.
He
nc
e,
sel
ect
ing
t
he
appr
opriat
e
MgSr
3
Si
2
O
8
:Eu
2+
,Mn
2+
con
ce
ntrati
on
is
ver
y
im
po
rt
ant
as
it
is
th
e
facto
r
deter
m
ining
the
WLED
s
’
c
olor
qual
it
y.
Vivid
ly
from
the
char
t,
when
there
is
a
n
increas
e
in
MgSr
3
Si
2
O
8
:
Eu
2
+
,Mn
2+
c
oncent
rati
on
from
2%
to
24
%
wt.
,
the
co
ncen
t
rati
on
of
ye
ll
ow
phospho
r
Y
AG
:C
e
3+
decli
nes
to
retai
n
the
ACCTs,
wh
ic
h
is
sim
il
ar
to
the
WLEDs str
uctu
re
with the
A
CC
T
of 66
00
K
.
Figure
3
pr
e
se
nts
the
em
issi
o
n
sp
ect
ra
of
th
e
W
LE
D
pac
ka
ge
with
6600
K
A
CC
T
wh
e
r
e
the
i
m
pacts
of
dif
fer
e
nt
co
ncen
t
rati
on
s
of
MgS
r
3
Si
2
O
8
:
Eu
2+
,
Mn
2+
ar
e
dem
on
strat
e
d
ob
viously
.
Be
sides,
the
s
ynthesis
of
the
sp
ect
ra
l
reg
io
ns
as
s
how
n
in
Fi
gure
3
act
ually
form
s
the
whit
e
li
gh
t.
As
can
be
see
n,
whe
n
the
Mg
Sr
3
Si
2
O
8
:Eu
2+
,Mn
2+
co
ncen
t
rati
on
ris
es
f
ro
m
2%
t
o
22%,
t
he
em
iss
ion
sp
ect
ru
m
increase
s
sig
nif
ic
antly
in
the
wa
veleng
t
h
ra
ng
e
of
680
nm
–
738
nm
.
Ho
we
ver,
this
change
will
be
insig
nificant
if
there
is
no
sp
ect
ral
inc
rea
se
in
the
tw
o
range
of
420
nm
-
48
0
nm
and
500
nm
-
640
n
m
.
Moreo
ve
r,
t
he
gro
wth
of
the
sp
ect
r
um
i
n
the
wa
vele
ngth
ra
nge
of
420
nm
-
48
0
nm
raises
the
lum
ino
us
flu
x
of
blu
e
li
gh
t
(b
l
ue
-
li
gh
t
scat
te
ring).
Th
us
,
it
can
be
addresse
d
that
a
hig
he
r
colo
r
tem
per
at
ure
will
le
ad
to
a
hig
her
s
pectral
em
issi
on
.
This
re
su
lt
is
ve
ry
i
m
po
rta
nt
to
the
a
ppli
cat
ion
of
Mg
Sr
3
Si
2
O
8
:Eu
2+
,M
n
2+
f
or
t
he
c
olo
r
qu
al
it
y
m
anag
em
ent
of
the
W
LE
Ds
with
high
col
or
te
m
per
at
ure.
Furtherm
ore,
with
these
find
i
ng
s
,
the
researc
h
pa
pe
r
co
uld
assure
the
abili
ty
of
MgSr
3
Si
2
O
8
:Eu
2+
,Mn
2+
in
enh
a
nci
ng
t
he
chrom
at
ic
qu
al
it
y
of
W
L
ED
pac
kages
with
bo
t
h
lo
w
col
or
te
m
per
at
ure
(66
00
K)
a
nd
high
c
olor
tem
per
at
ur
e
(77
00
K).
T
he
refor
e
,
the
s
uitable
MgSr
3
Si
2
O
8
:Eu
2+
,Mn
2+
c
on
c
entrati
on
is
decide
d
acc
ordin
g
to
the
requirem
ents
from
m
anu
fac
turers
.
If
the
goal
is
to
achieve
a
high
col
or
qual
it
y
fo
r
WL
ED
products,
a
sm
a
ll
red
uct
ion
in
l
um
ino
us
fl
ux
is acc
eptable.
Evaluation Warning : The document was created with Spire.PDF for Python.
IS
S
N
:
2088
-
8708
In
t J
Elec
&
C
om
p
En
g,
V
ol.
10
, No
.
4
,
A
ugus
t
2020
:
3501
-
3507
3504
Figure
2. The
c
hange i
n phos
phor c
oncentrati
on
for
m
ai
ntaining
the
A
CC
T
of
W
LE
Ds
Figure
3. Em
is
sion spect
ra
of
6600
K WLE
D
s w
it
h
diff
e
re
nt MgSr
3
Si
2
O
8
:Eu
2+
,M
n
2+
co
ncen
t
rati
on
Dem
on
strat
ed
in
Fig
ure
4
is
t
he
upwa
rd
tren
d
in
the
col
or
r
end
e
rin
g
i
nd
e
x
f
ollow
i
ng
the
increase
of
MgSr
3
Si
2
O
8
:Eu
2+
,
Mn
2+
phospho
r
c
on
ce
ntr
at
ion
.
T
his
tre
nd
can
be
e
xp
la
ined
by
the
abs
orption
pro
cess
of
the
re
d
Mg
Sr
3
Si
2
O
8
:E
u
2+
,
Mn
2+
phosphor
la
ye
r
.
S
pecifica
ll
y,
as
soon
as
the
re
d
phosp
hors
MgSr
3
Si
2
O
8
:Eu
2+
,Mn
2+
a
bs
or
b
the
bl
ue
li
gh
t
e
m
itted
f
ro
m
the
bl
ue
c
hip
s
,
they
will
tu
rn
these
blu
e
li
gh
ts
into
red
li
gh
ts.
Mo
r
eov
e
r,
besi
des
the
bl
ue
li
ght,
t
his
re
d
phosp
hor
M
gSr
3
Si
2
O
8
:Eu
2+
,Mn
2+
al
s
o
a
bs
or
bs
the
ye
ll
ow
li
gh
t.
H
ow
e
ve
r
,
wh
e
n
dra
wing
a
com
par
iso
n
betwee
n
thes
e
two
abs
orption
processes
,
it
has
turn
e
d
out
that
the
bl
ue
li
gh
t
from
LED
chi
ps
is
a
bs
or
bed
m
or
e
strongly
than
t
he
ye
ll
ow
li
ght
beca
use
of
t
he
a
bsor
ption
pro
per
ti
es
of
the
m
at
erial
,
wh
ic
h
certai
nl
y
le
ads
to
the
la
rg
er
am
ou
nt
of
red
li
ght
com
po
nen
ts
inside
the
WLE
Ds
w
hen
Mg
Sr
3
Si
2
O
8
:Eu
2+
,M
n
2+
is
ad
de
d.
Co
nse
qu
e
ntly
,
the
c
olor
renderi
ng
ind
ex
(CRI
)
r
eaches
a
highe
r
val
ue.
CR
I
is
an
im
portant
facto
r
that
nee
ds
to
be
fo
c
us
e
d
o
n
wh
e
n
c
hoos
i
ng
a
m
od
ern
m
od
el
of
WLE
Ds,
s
o
the
hig
he
r
the
CR
I
is,
the
m
or
e
exp
e
ns
ive
th
e
LED
pro
du
ct
s
beco
m
e.
No
ne
thele
ss,
CR
I
canno
t
fu
ll
y
evaluate
the
W
LE
Ds
’
c
olor
qual
it
y
si
nce
it
is
j
us
t
one
of
the
m
ea
su
rem
ent
facto
rs.
T
her
e
fore,
a
ne
w
ind
e
x
cal
le
d
c
o
lo
r
qu
al
it
y
sc
al
e
(CQ
S)
is
i
ntr
oduce
d
to
be
an
al
te
rn
at
iv
e
beca
us
e
it
c
ov
e
rs
t
hr
ee
dif
fer
e
nt
factors,
inclu
di
ng
the
CR
I,
th
e
viewer
s
’
pr
e
f
eren
ce
a
nd
the
colo
r
coor
din
at
es.
The
CQS
s
hows
a
co
ns
id
erab
le
i
m
pr
ovem
ent
with
the
c
once
ntrati
on
of
the
red
phosp
hor
MgSr
3
Si
2
O
8
:Eu
2+
,Mn
2+
,
a
s
il
lustrate
d
i
n
Fi
gure
5.
It
is
obvious
t
o
a
dm
it
that
t
he
red
ph
osphor
MgS
r
3
Si
2
O
8
:Eu
2+
,Mn
2+
ca
n
en
hance
the
c
olor
qu
al
it
y
of
w
hite
li
gh
t
LE
Ds
with
dual
-
la
ye
r
phosp
hor
str
uct
ur
e
.
T
hu
s
,
this
resu
lt
play
s
an
im
po
rtant
r
ol
e
in
accom
pli
sh
in
g
the
go
al
of
col
or
qual
it
y
enh
a
ncem
ent.
In
ad
diti
on
,
a
no
t
her
adv
a
ntage
of
this
ty
pe
of
ph
ospho
r
is
it
s
lo
w
cost
wh
ic
h
is
ben
ef
ic
ia
l
to
m
ass
p
rod
uction,
and
thu
s,
that
Mg
Sr
3
Si
2
O
8
:E
u
2+
,
Mn
2+
is
widely
us
ed
in
this
in
du
st
ry
can
be
easi
ly
unde
rstood.
H
ow
e
ve
r,
t
he
down
si
de
w
hen
util
iz
ing
this
phosp
hor
m
at
erial
is
that
it
ca
n
ca
us
e
a d
ec
rease i
n
t
he
lum
en
out
put o
f WLE
Ds.
Figure
4. The
c
olor r
e
nderi
ng
ind
e
x of
W
L
E
Ds
as
a
functi
on
of
M
gSr
3
Si
2
O
8
:E
u
2+
,
Mn
2+
co
ncen
tra
ti
on
Figure
5. The
c
olor
qu
al
it
y
sc
al
e o
f
W
L
EDs
as a
functi
on
of
M
gSr
3
Si
2
O
8
:E
u
2+
,
Mn
2+
co
nce
ntr
at
ion
In
this
pa
rt,
w
e
will
sh
ow
a
nd
e
xp
la
in
the
m
at
he
m
a
ti
cal
m
od
el
of
the
transm
i
tt
ed
blu
e
li
gh
t
an
d
conve
rted
ye
ll
ow
li
ght
in
t
he
double
-
la
ye
r
phosp
hor
str
uct
ur
e
t
o
obta
in
a
sign
ific
a
nt
en
ha
ncem
ent
of
th
e
LED
eff
ic
acy
. T
he
a
sy
m
m
e
tric
al
SP
D of m
on
oc
hrom
e LED
is t
ypic
al
ly
m
od
el
ed wit
h Gaussi
an fu
nctio
n
[
22
,
23]
:
Evaluation Warning : The document was created with Spire.PDF for Python.
In
t J
Elec
&
C
om
p
En
g
IS
S
N:
20
88
-
8708
En
hancin
g
t
he
CRI
and
l
um
e
n o
utput f
or t
he 660
0
K
W
LE
D
wi
th convex
-
du
al
-
layer
…
(
Thuc Mi
nh Bu
i
)
3505
2
2
)
(
*
5
.
0
e
x
p
2
1
p
e
a
k
opt
P
P
(1)
wh
e
re σ
d
e
pe
nds
on pea
k wa
velen
gth
λ
peak
a
nd F
WH
M Δ
λ
can
be
e
xpress
ed
as
;
2
ln
2
2
2
ln
2
2
2
ln
2
2
2
1
2
2
1
2
2
hc
hc
hc
hc
hc
hc
E
p
e
a
k
p
e
a
k
p
e
a
k
(2)
The
S
PD
of
a
wh
it
e
LE
D
util
iz
ing
ye
ll
ow
Y
AG
ph
os
ph
or
and
bl
ue
LE
D
chip
ca
n
hypot
hetic
al
ly
be
viewe
d
as
the
aggre
gate
of
t
he
bl
ue
an
d
ye
ll
ow
sp
ect
ra.
Howe
ver,
in
f
act
,
the
suppo
sed
ye
ll
ow
phos
ph
or
rad
ia
te
s
li
gh
t
i
n
both
of
t
he
ye
ll
ow
an
d
gr
ee
n
sp
ect
ra
as
de
m
on
strat
ed
fro
m
the
deli
ber
at
e
sp
ect
ra
in
Figure
3.
In
the e
ven
t t
ha
t a blue
and
a
ye
ll
ow
r
an
ge
a
re p
ic
ke
d,
th
e con
t
rast b
et
wee
n
the esse
ntial
l
y est
i
m
at
ed
SPD
a
nd
twofol
d
sh
a
di
ng
(b
l
ue
an
d
ye
ll
ow
sh
a
ding)
ra
nge
m
od
el
can
be
spo
ken
for
a
gree
n
ra
ng
e
.
I
n
th
is
w
ay
,
consi
der
i
ng
t
he
pr
act
ic
al
ci
rcu
m
sta
nce,
a
gr
ee
n
ra
nge
can
be
a
dd
e
d
t
o
the
tw
ofold
range
m
od
el
to
f
or
m
the
acc
om
pan
yi
ng
i
nv
est
iga
ti
ve
tri
-
s
pectr
um
(B
–
G
–
Y
)
m
od
el
re
pr
e
sented
by
(
3)
a
nd
s
ub
se
quently
al
te
red
as
(
4)
.
2
2
_
_
2
2
_
_
2
2
_
_
)
(
*
5
.
0
e
x
p
2
1
)
(
*
5
.
0
e
x
p
2
1
)
(
*
5
.
0
e
x
p
2
1
y
y
p
e
a
k
y
y
opt
g
g
p
e
a
k
g
g
opt
b
b
p
e
a
k
b
b
opt
P
P
P
P
(3)
2
2
_
_
2
2
_
_
2
2
_
_
)
(
*
5
.
0
e
x
p
2
1
)
(
*
5
.
0
e
x
p
2
1
)
(
*
5
.
0
e
x
p
2
1
y
y
p
e
a
k
y
t
o
t
a
l
opt
y
g
g
p
e
a
k
g
t
o
t
a
l
opt
g
b
b
p
e
a
k
b
t
o
t
a
l
opt
b
P
P
P
P
(4)
in which:
-
P
λ
Sp
ect
ral powe
r dist
rib
ution (S
PD)
(m
W/nm
).
-
h
Pla
nck’s
c
onsta
nt
(J.
s
).
-
c
Sp
ee
d of l
ig
ht (
m
·
s
−1
).
-
λ
Wav
el
e
ng
t
h (
nm
).
-
P
opt
Op
ti
cal
pow
e
r (
W)
.
-
λ
peak
Pea
k wa
velen
gth
(
nm
).
-
Δλ
F
ull
-
width at
h
al
f
-
m
axi
m
um
(
F
WH
M)
(
nm
).
-
η
Ra
ti
o o
f
s
pe
ci
fic sp
ect
ra
to white s
pectr
um
, d
i
m
ension
le
ss.
-
P
opt_b
,
P
opt_g
,
P
opt_y
,
an
d
P
opt_total
Op
ti
cal
powe
r
(
W)
f
or
t
he
blu
e,
gr
ee
n,
ye
ll
ow,
an
d
wh
it
e
s
pectra,
resp
ect
ively
.
-
λ
peak_b
, λ
peak_g
,
an
d
λ
peak_y
Pea
k wav
el
e
ng
t
hs
(n
m
)
f
or
t
he blue, g
reen, a
nd
ye
ll
ow
s
pectra,
r
es
pecti
vely
.
-
σ
b
, σ
g
,
a
nd
σ
y
F
WH
M
-
relat
e
d
c
oeffici
ents
(
nm
)
for
the
b
l
ue
, gree
n,
a
nd y
el
low
s
pectra,
re
sp
ect
ively
.
-
η
b
, η
g
,
and η
y
Ra
ti
os
of
blu
e
–
gr
ee
n
–
ye
ll
ow
(
B
–
G
–
Y
)
s
pectr
a to
wh
it
e s
pe
c
trum
, r
especti
ve
ly
, d
im
ensionle
ss.
-
λ
1
, λ
2
Wa
veleng
t
hs
at
half o
f
the
peak inte
nsi
ty
.
Evaluation Warning : The document was created with Spire.PDF for Python.
IS
S
N
:
2088
-
8708
In
t J
Elec
&
C
om
p
En
g,
V
ol.
10
, No
.
4
,
A
ugus
t
2020
:
3501
-
3507
3506
Ther
e
f
or
e,
the
SP
D
m
od
el
in
g
f
or
the
ph
ospho
r
-
c
oated
w
hite
LED
can
be
e
xpresse
d
a
s
a
tric
ol
or
sp
ect
r
um
,
wh
ic
h
can
be
c
on
si
der
e
d
as
an
ext
end
e
d
Ga
us
sia
n
m
od
el
.
The
scat
te
ring
of
MgSr
3
Si
2
O
8
:Eu
2+
,Mn
2+
phospho
r
pa
rtic
le
was
analy
zed
by
usi
ng
th
e
Mi
e
-
theo
ry.
In
a
dd
it
io
n,
th
e
scat
te
ring
cr
os
s
sect
io
n
C
sca
for
sp
he
rical
pa
rtic
le
s
can
be
com
pu
te
d
by
the
f
ollow
i
ng
ex
pressi
on
by
ap
plyi
ng
t
he
Mi
e
theo
r
y
[24].
The
tra
ns
m
it
ted
li
ght p
ower
c
an be cal
c
ulate
d by the
Lam
ber
t
-
Be
er la
w [25]
:
=
(
−
)
(5)
w
he
re
I
0
,
L
,
and
µ
ext
repre
sent
the
incid
ent
li
gh
t
pow
er
the
thick
n
e
ss
of
phosphor
la
ye
r
(m
m
),
a
nd
the
extinct
io
n
coeffic
ie
nt,
r
especti
vely
.
More
ov
e
r,
the
extinct
ion
c
oeffici
ent
can
be
dem
on
str
at
ed
as
the
f
ollow
i
ng
form
ula:
µ
ext
=
N
r
.C
ext
,
in
wh
ic
h
N
r
ind
i
cat
es
the
num
ber
de
ns
it
y
distribu
ti
on
of
pa
rtic
le
s
(m
m
-
3
),
w
hile
C
ext
(m
m
2
)
is k
now
n
as t
he
e
xt
in
ct
ion
c
ross
-
s
ect
ion
of ph
ospho
r partic
le
s.
It
can
be
im
p
li
ed
from
(5
)
that
the
dual
-
l
ay
er
rem
ote
ph
osp
hor
re
su
lt
s
in
the
la
r
ge
r
lum
ino
us
eff
ic
ie
ncy
f
or
the
LE
D
pac
ka
ges
tha
n
t
he
sing
le
-
la
ye
r
phosp
hor.
He
nc
e,
the
ben
e
fit
of
us
in
g
dual
-
la
ye
r
rem
ote
phos
phor
la
ye
r
i
n
yi
el
din
g
bette
r
lum
en
outp
ut
is
s
uccess
f
u
ll
y
dem
on
str
at
ed
in
this
stud
y
.
On
the
oth
e
r
ha
nd,
the
co
nce
ntrati
on
of
re
d
phosp
hor
M
gSr
3
Si
2
O
8
:E
u
2+
,
Mn
2+
great
ly
aff
ect
s
t
he
op
ti
c
al
path
of
this
dual
-
la
ye
r
rem
ote
ph
os
ph
or
str
uctu
re.
Vivi
dly,
the
red
uc
ti
o
n
fa
ct
or
µ
ext
has
a
direct
propor
t
ion
t
o
the
MgS
r
3
Si
2
O
8
:Eu
2+
,M
n
2+
co
ncen
t
rati
on,
but
an
i
nv
e
rse
rati
o
to
the
li
ght
transm
issi
on
powe
r.
Th
us
,
as
t
he
thick
ness
of
t
he
two
phosp
hor
la
ye
rs
a
re
f
ixed,
a
dec
rea
se
in
lum
ino
us
flu
x
can
occ
ur
with
the
grow
t
h
of
MgSr
3
Si
2
O
8
:Eu
2+
,Mn
2+
c
on
c
entrati
on,
le
a
di
ng
t
o
t
he
dec
li
ne
in
al
l
five
CC
Ts,
as
s
hown
i
n
Figure
6.
O
bviou
sly
,
w
he
n
t
he
co
nce
ntrati
on
of
Mg
Sr
3
Si
2
O
8
:Eu
2+
,M
n
2+
reaches
24
%
wt,
t
he
lum
inous
flu
x
decr
ease
s
dr
a
m
at
ic
ally.
Ho
wev
e
r,
this
dra
wb
ac
k
in
lum
e
n
outp
ut
can
be
acce
pted
due
to
the
gr
eat
be
nef
it
s
that
the
red
phosp
hor
Mg
Sr
3
Si
2
O
8
:Eu
2+
,M
n
2+
br
in
gs
to
t
he
W
L
EDs
,
inclu
ding
the
bette
r
CR
I
an
d
CQS
.
In
ad
diti
on,
dual
-
la
ye
r
rem
ote
phosp
hor
c
an
yi
el
d
high
er
lum
ino
us
fl
ux
tha
n
t
h
e
si
ng
le
-
la
ye
r
phospho
r
without
the
pr
esence
of
re
d
phospho
rs.
T
he
refor
e
,
the
only
issue
her
e
i
s
the
pur
pose
of
m
anu
fact
ures
for
determ
ining
th
e
m
os
t
app
r
op
riat
e
phosp
hor
co
ncen
tr
at
ions
of
Mg
Sr
3
Si
2
O
8
:Eu
2+
,M
n
2+
wh
e
n
m
ass
producin
g
WLE
Ds pro
duct
s.
Figure
6.
The
lum
ino
us
flu
x o
f WLE
Ds
as
a
functi
on
of
M
gSr
3
Si
2
O
8
:E
u
2+
,
Mn
2+
co
nce
ntr
at
ion
4.
CONCL
US
I
O
N
Fr
om
this
arti
cl
e,
a
sim
ple
m
et
ho
d
f
or
be
tt
er
perf
or
m
ance
of
a
dju
sti
ng
the
col
or
wi
th
w
hite
-
li
ght
LED
m
odules
w
hile
retai
ni
ng
t
he
high
CR
I
an
d
l
um
ino
us
e
ff
ic
acy
is
pro
posed.
De
pendi
ng
on
the
m
anu
facture
rs'
req
ui
rem
e
nts,
a
col
or
de
sign
m
od
el
is
bu
il
t
base
d
on
the
ap
plica
ti
on
s
of
Be
er
’s
la
w
a
nd
li
near
c
onve
rsion
w
hich
ca
n
s
upport
t
he
different
w
hite
-
li
ght
LE
Ds.
Th
e
si
m
ulate
d
an
d
exp
e
rim
ental
sp
ect
ra
sh
ow
po
sit
ive
ov
e
rl
ap
pe
d
res
ults.
More
over
,
the
bi
gg
est
diff
e
ren
ce
betwe
en
the
m
easur
e
d
an
d
sim
ulated
CI
E
1931
colo
r
co
ordi
nates
is
identifie
d
by
ap
prox
im
at
el
y
0.
0063
wit
h
the
6600
K
CC
T.
He
nce,
it
is
po
ssible
to
structu
re t
he pr
opos
e
d
c
olor
de
sign m
od
el
and
get it
appli
ed
e
asi
ly
.
REFERE
NCE
S
[1]
A.
A.
Alat
awi
,
e
t
al.
,
“
High
-
power
blue
superlum
ine
sce
n
t
diode
f
or
high
CRI
li
ghti
ng
and
high
-
sp
ee
d
visibl
e
li
ght
comm
unic
at
ion,”
Opti
cs
E
xpre
ss
,
vol
.
26
,
no
.
20
,
pp.
26355
-
2636
4,
2018
.
[2]
J.
F.
Ruan,
et
al.
,
“
Phase
tra
nsform
at
ion
in
duce
d
rev
e
rsibl
e
m
odula
ti
on
o
f
upconve
rsion
luminesce
nce
of
W
O3:Yb3+,
Er3
+
phosphor for
sw
it
chi
ng
device
s
,
”
Opt
ic
s Le
tt
ers
,
vol
.
43
,
no
.
16
,
pp.
3885
-
3888
,
2018.
Evaluation Warning : The document was created with Spire.PDF for Python.
In
t J
Elec
&
C
om
p
En
g
IS
S
N:
20
88
-
8708
En
hancin
g
t
he
CRI
and
l
um
e
n o
utput f
or t
he 660
0
K
W
LE
D
wi
th convex
-
du
al
-
layer
…
(
Thuc Mi
nh Bu
i
)
3507
[3]
Y.
Yuan,
et
a
l.
,
“
High
luminous
fluore
sce
n
ce
g
en
era
t
ion
using
Ce
:YAG
tra
nspare
nt
ce
r
amic
ex
ci
t
ed
b
y
b
lue
l
ase
r
diode
,
”
Opt
ic
al
Mate
rials
Ex
pre
ss
,
vol. 8,
no.
9,
pp.
2760
-
2767
,
Sep.
2018
.
[4]
S.
R.
Chung,
et
al.
,
“
Full
col
or
display
fab
r
ica
te
d
b
y
CdS
e
bi
-
col
or
quan
tum
dots
-
base
d
whit
e
li
gh
t
-
emitting
diode
s,”
Opti
cal
Mate
rials
Ex
pre
ss
,
vol. 8,
no.
9,
pp.
2677
-
2686
,
2018.
[5]
F.
Steudel,
et
al.
,
“
Pixel
a
te
d
pho
sphors
for
high
-
resolut
ion
and
h
igh
-
cont
r
ast
whi
te
l
ight
sour
ce
s,
”
Opti
cs
Ex
pres
s
,
vol.
26
,
no
.
20
,
p
p.
26134
-
26144
,
2018.
[6]
L.
Ta
ng
,
et
al
.
,
“
Photo
-
induced
luminesce
nc
e
degr
adation
i
n
Ce,
Yb
co
-
doped
y
t
tri
um
al
um
inum
gar
net
phosphors
,
”
App
li
ed
Optic
s
,
vol
.
57,
no
.
26
,
pp
.
7
627
-
7633,
2018
.
[7]
R.
Le
i
,
et
al
.
,
“
I
nflue
nc
e
of
exc
i
ta
ti
on
power
an
d
doping
conc
en
tra
ti
on
on
th
e
upconve
rsion
emi
ss
ion
and
opti
cal
te
m
per
at
ur
e
sen
sing
beha
vior
o
f
Er3+
:
BaGd2(
MoO
4)4
p
hosph
ors,”
Optic
al
M
ate
rials
Ex
press
,
vol.
8,
no
.
10,
pp.
3023
-
3035
,
Oct
.
2018
.
[8]
X.
Huang,
et
al.
,
“
High
-
eff
ic
ie
n
c
y
and
the
rm
all
y
stabl
e
far
-
r
ed
-
e
m
it
ti
ng
NaL
aMg
W
O6:Mn4+
pho
sphors
for
indoor
pla
nt
growth
l
ig
ht
-
emitt
ing
diod
es,
”
Opt
ic
s Le
tt
e
rs
,
vol. 43,
no.
1
4,
pp
.
3305
-
330
8,
2018
.
[9]
V.
V.
Bakhmet’
ev,
e
t
al.
,
“
Eff
ect
of
coppe
r
in
tro
duct
ion
and
sho
ck
-
wave
proc
essing
of
zi
nc
sulf
i
de
on
the
spec
tr
al
cha
ra
cteri
sti
cs
of
a
m
anga
nese
-
a
ct
iv
at
ed
phosph
or
s
y
nth
esiz
ed
f
rom
it
,
”
in
Jour
nal
of
Opti
cal
T
ec
hnolog
y
c/c
of
Optic
hesk
ii
Zhur
nal
,
vo
l. 85,
no.
6,
pp
.
367
-
370
,
J
un
.
2018
.
[10]
Y.
Ma,
e
t
al
.
,
“
Phos
phor
m
odel
ing
base
d
on
f
l
uore
sce
nt
r
adiat
ive
tr
ansfe
r
equ
at
ion
,
”
Opti
cs
E
xpre
ss
,
vol.
26
,
no.
13
,
pp
.
1644
2
-
16455,
2018
.
[11]
Z.
W
en,
e
t
al.
,
“
Fabric
at
ion
an
d
opti
cal
prope
r
ti
es
of
Pr3+
-
dop
ed
Ba
(Sn,
Zr,
Mg,
Ta
)
O3
trans
par
ent
c
era
m
i
c
phosphor,”
Opti
cs
Letters
,
vol
.
4
3,
no
.
11
,
pp
.
24
38
-
2441,
2018
.
[12]
X.
L.
Song,
et
al.
,
“
Bia
xial
h
y
per
bo
lic
m
et
a
m
at
eri
a
ls
using
ani
sotropi
c
fe
w
-
lay
er
bl
ac
k
p
hospho
rus,”
Optics
Ex
press
,
vol
.
26
,
no.
5,
pp.
5469
-
5477,
2018
.
[13]
J.
Cao,
et
al
.
,
“
Upconve
rsion
lu
m
ine
sce
nce
of
B
a3L
a(PO4)3:Yb
3+
-
Er3+/T
m
3+
phosphors
for
opti
m
al
t
empera
t
ure
sensing,
”
Appl
i
e
d
Optic
s
,
vol
.
57
,
pp
.
1345
-
1350
,
2018.
[14]
Y.
Peng,
et
al.
,
“
Flexi
ble
f
abr
i
c
ation
of
a
pat
te
rn
e
d
red
phosphor
lay
er
on
a
YA
G:Ce3+
phosphor
-
in
-
gla
ss
for
high
-
power
W
LE
Ds
,
”
Optic
a
l
Mat
eria
ls E
xpre
ss
,
vol.
8,
no
.
3
,
pp
.
605
-
614,
2018
.
[15]
H.
Lee,
e
t
al
.
,
“
Phos
phor
-
in
-
gla
ss
with
Nd
-
dope
d
gla
ss
for
a
wh
it
e
LE
D
wi
th
a
wide
co
lor
g
amut,
”
Optic
s
Lette
rs
,
vol.
43
,
no
.
4
,
pp
.
627
-
630
,
2018
.
[16]
T.
X.
Lee,
et
a
l.
,
“
Minia
tur
iz
ed
LE
D
primar
y
op
ti
cs
design
used
for
short
-
dista
nc
e
col
or
m
ixi
ng,
”
Appl
i
ed
Opti
cs
,
vol.
55
,
no
.
32
,
p
p.
9067
-
9073
,
2
016.
[17]
J.
Gade
ga
ard
,
e
t
al.
,
“
High
-
outp
ut
LE
D
-
b
ase
d
l
i
ght
en
gin
e
for
p
rofil
e
li
gh
ti
ng
f
i
xture
s
with
h
igh
col
or
uniformit
y
using f
ree
fo
rm
ref
lector
s,
”
App
lied
Opti
cs
,
vo
l. 5
5,
no
.
6
,
pp
.
135
6
-
1365,
2016
.
[18]
B.
J.
Chen,
et
a
l.
,
“
Free
form
m
ic
rostruc
tur
e
li
n
e
ar
li
ght
emitt
er
design
for
a
natural
li
gh
t
illum
ina
ti
on
s
y
s
te
m
,”
Appl
ie
d
Opti
cs
,
vol.
54
,
no
.
28
,
p
p.
E159
-
E164, 2
015.
[19]
S.
P.
Ying,
e
t
al.
,
“
Im
proving
the
col
or
unifo
rm
ity
of
m
ult
ip
l
e
co
lore
d
li
ght
-
emitt
ing
d
iode
s
using
a
per
iod
i
c
m
ic
rostruc
ture s
urfa
ce,”
App
li
ed
Optic
s
,
vo
l. 54,
no.
28
,
pp
.
E75
-
E79,
2015
.
[20]
S.
W
ang,
et
al.
,
“
Im
prove
m
ent
in
angu
la
r
col
or
uniformit
y
of
white
li
ght
-
emit
ti
ng
diod
es
usin
g
scre
en
-
printed
m
ult
il
a
y
e
r
phosp
hor
-
in
-
gla
ss
,
”
A
ppli
ed
Optic
s
,
v
ol.
53
,
no
.
36
,
pp
.
8492
-
8498
,
20
14.
[21]
W
.
S.
Sun,
et
al
.
,
“
Com
pac
t
LED
proje
ct
or
desi
gn
with
high
un
iformit
y
and
ef
fi
ci
en
c
y
,
”
Appl
i
ed
Optic
s
,
vol.
53,
no.
39
,
pp
.
H227
-
H232,
Oct
.
201
4.
[22]
M.
L.
Piao
,
e
t
al
.
,
“
Achi
evi
ng
h
i
gh
le
v
el
s
of
col
o
r
uniformit
y
and
opti
c
al
eff
i
cienc
y
for
a
wedge
-
sh
ape
d
wav
egui
d
e
hea
d
-
m
ounte
d
di
spla
y
using
a
ph
otopoly
m
er
,
”
Ap
pli
ed
Optic
s
,
vol
.
53
,
no
.
10
,
pp
.
2180
-
2186,
201
4.
[23]
K.
C.
Huang,
et
al.
,
“
Im
prove
d
CCT
uniformity
of
white
LE
D
using
remote
p
hosphor
with
pat
te
rn
ed
sapphire
subs
tra
te
,
”
Appl
i
ed
Opti
cs
,
vo
l. 5
2,
no
.
30
,
pp
.
73
76
-
7381,
201
3
.
[24]
S.
Bindai,
et
al
.
,
“
Re
al
i
za
t
ion
of
phosphor
-
in
-
gla
ss
thi
n
f
il
m
on
soda
-
li
m
e
si
li
c
at
e
gla
ss
wit
h
low
sintering
te
m
per
at
ur
e
for
high
co
lor
r
endering
whit
e LE
Ds
,
”
Appl
i
ed
Opt
ics
,
vol. 58,
no.
9,
pp.
2372
-
2381
,
2019.
[25]
C.
Huang,
et
a
l.
,
“
Bandwidt
h
co
rre
ctio
n
of
spec
t
ral
m
ea
surem
ent
base
d
on
Le
ven
ber
g
–
Marqua
rdt
al
gorit
hm
with
improved
Ti
kho
nov
reg
ul
ariza
t
io
n,
”
Appl
i
ed
Opt
i
cs
,
vol
.
58
,
no
.
9
,
pp
.
2166
-
2173
,
2019.
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