11. Gas Discharge Displays

Transcription

11. Gas Discharge Displays
Content
11.1
11
1T
Technologies
h l i ffor Fl
Flatt Displays
Di l
11.2 Construction of Gas Discharge Displays
11.3 Manufacturing Process
11.4 Light Generation in Plasma Displays
11.5 Operation of the Gas Discharge
11.6 Selection Criteria for Display Phosphors
11.7 Phosphors in CRTs and PDPs
11 8 R
11.8
Red
d PDP Ph
Phosphors
h
11.9 Green PDP Phosphors
11.10 Blue PDP Phosphors
11.11 Status and Outlook
Incoherent light sources
Prof. Dr. T. Jüstel
Chapter Gas Discharge Displays
Slide 1
11.1 Technologies for Flat Displays
Technology
Efficiency
Max. size
Areas of application
Organic
g
EL
Inorg. EL
FED
LCD
2 lm/W
1 lm/W
5 lm/W
4 lm/W
10‘‘
17‘‘
17‘‘
65‘‘
65
Automobiles, mobile p
phones
Instrument displays
PALC
LED Array
Projection TV
PDP
4 lm/W
8 - 10 lm/W
5 lm/W
5 lm/W
40 - 50‘‘
> 100
100‘‘
50 - 60‘‘
~ 300‘‘
Billboards
TV
TV, scoreboards
CRT
3 lm/W
36‘‘
TV, monitors
Laptops, monitors, LCD TV
Remark: Theoretical limit for white light ~ 300 lm/Wopt.

Energy efficiency of displays ~ 1 – 3%
Slide 2
Gas Discharge Displays
Properties
Flat and large
g
(32 - 300 inch)
Thin ~ 100 mm
Lightweight
~ 20 - 30 kg for 42-inch
Large viewing angle
~ 170°
60" HDTV
HDTV-PDP
PDP
No distortion
Unaffected by ext.
magnetic fields
Slide 3
E i i Display
Emissive
Di l Types
T
Technology
gy
CRT
PDP
Excitation source
Electron beam
Gas discharge
Excitation energy
20 - 30 keV
6 - 10 eV
Phosphors
Sulfides
Oxides
Gas pressure
< 10-33 mbar
200 - 300 mbar
Viewing angle
> 160°
> 160°
Slide 4
11.111.1
Technologien
Technologies
fürfor
flache
FlatBildschirme
Displays
Plasma displays 1929
Slide 5
Si
Simplified
ifi layer structure
Front glass plate
Bus electrode (ITO)
Dielectric
MgO protective layer
RGB phosphor
Dielectric
Address electrodes (Ag)
R
G
B
Rear
glass plate (PD200)
Gas filling ~ 500 Torr Ne with 3 - 5 % Xe
Slide 6
Structure of a plasma cell
Glass back panel
Structuring by barrier ribs
Conical structure
TiO2-film as a reflector
Phosphor layer (with
additives)
U-shaped
U
shaped structure
Slide 7
Preparation of the front plate
FRONT PLATE
substrate+ITO
from supplier
lithography
screenprinting of
2nd diel. layer
PD200
lithography
evaporation Cr/Cu/Cr
screenprinting of
1st diel.
diel layer
firing
(580C)
(580
C)
firing
(580C)
evaporation MgO
(0.6 m)
to assembly
Slide 8
Preparation of the back plate
BACK PLATE
substrate from
supplier
application of
barrier rib frit
firing
(530C)
application of
powderblast
resist
screenprinting
of phosphors
(3x)
powderblasting
mounting of
pumping stem, firing
PD200
evaporation
i Cr/Al/Cr
C /Al/C
(0.1/2.0/0.2 m)
lithography
screenprinting of
protective layer
firing
(560C)
to assembly
Slide 9
Functional principle
Visible
light
Visible light
Front glass plate
Phosphor
Gas discharge
VUV
VUV
VUV light
Rear glass plate
Noble gas discharge
~ 200 µm
Slide 10
Efficiency of light generation
display = discharge . UV . phosphor .  out-coupling
PDP-cell
PDP
cell
Xe2 *- lamp
Hg - lamp
 Plasma
24 %
70 %
75 %
 UV
40 %
90 %
98 %
 Phosphor
20 %
25 %
44 %
 Coupling out
50 %
90 %
98 %
 Display
1.0 %
14 %
30 %
Light output
3 lm/W
40 lm/W
90 lm/W
Slide 11
Light generation in Ne discharges
Ne + e-  Ne* + e-
Ne* + Ar  Ne + Ar+ + eNe* + Xe  Ne + Xe+ + e((Penning
g ionization))
Emission inte
ensity [a.u.]
Ne*  Ne + h(74 nm + vis.)
1,0
0,8
0,6
0,4
0,2
0,0
400
- Monochrome PDPs
- Neon discharge lamps
- Hg-discharge lamps with Ne-filling "neon lamps"
500
600
Wavelength [nm]
700
800
Gas mixtures of Ne/Ar or Ne/Xe thus cause a reduction of the ignition voltage by
the so-called “Penning effect”
Slide 12
Light generation in Xe/Ne discharge


+ h(828 nm)
+ h(823 nm)
Xe(3P2)  Xe(1S0) + h(147 nm)
172
2
1u
Continuum
3P
1
+ 1S0
B
3P
2
+ 1S0
A
1 +
u
Wavelength / nm
W
Xe**
Xe(3P1)
Xe(3P2)
2nd
3 +
u
1st
2nd
Continuum
1S
0
Resonance Line
Low Pressure
Resonance
Line
1 +
g
1st Continuum
147
 Xe(3P1) + e Xe(3P2) + e Xe**
Xe(1S0) + e-
Energy
E
High Pressure
2
3
4
5
+ 1S0
6
7
Internuclear Distance (Å
Xe(3P1) + Xe(1S0) + M  Xe2*(1u+) + M / Xe(3P2) + Xe(1S0) + M  Xe2*(3u+) + M
Xe2*(3u+)  Xe2*(1g+) + h(150 nm)  2 Xe(1S0)
Xe2*(1u+)  Xe2*(1g+) + h(172 nm)  2 Xe(1S0)
X
Slide 13
Light generation in Xe/Ne discharge
Emission
n intensity [a.u.]
1,0
0,8
20% Xe
0,6
10% Xe
04
0,4
1% Xe
Relattive proportion of radiation
1,000
172 nm
147 nm
0,100
150 nm
0,010
0,001
0,2
0
50
100
150
200
Xenon partial pressure / mbar
0,0
140
150
160
170
180
190
Wavelength [nm]
50% Xe2*-excimer
-excimer and 50% Xe
Xe* resonance emission at 25 mbar Xe partial pressure
PDPs 2005: Xe-percentage at 10 - 15% and 300 mbar total pressure, i.e., Xe2*-excimer
radiation predominates
Slide 14
Influence of Xe partial pressure
660 mbar, 500 V, 50 kHz
4000
6
600
5
500
3
2
Sustain
nvoltage (V)
2000
Effficacy (lm/W)
4
2
Luminance (cd/m )
3000
400
300
200
1000
1
Vsm
100
Vf
0
0
0
5
10
Xe-content (%)
15
20
0
0
5
10
15
Xe-content (%)
With the Xe pressure the efficiency and the ignition voltage increases
Slide 15
20
Dependence on the Xe/Ne partial pressure
100% N
Ne
N /X
Ne/Xe
100% X
Xe
Low ignition voltage
~ 300 V
High ignition voltage
~ 2 kV
Visible emissions
580 - 720 nm
(Monochrome red)
No visible emission
(color is defined by the
phosphor)
VUV emission
74 nm
VUV emission
147 150
147,
150, 172 nm
Slide 16
Dielectric barrier discharges
Schematic operation of a PDP-cell
Course of voltage and current
Dielectric
V
0
negative
ti
glow
0
negative
glow
V
I
0
t
Slide 17
Addressing the pixel
Each p
pixel has 2n brightness
g
levels
 By 8-bit addressing one obtains 28 = 256 brightness levels
 In a RGB-display there is therefore 2563 = 16.7 million colors available
1
2
4
8
16
32
1 Frame: Will be specified
p
by
y the refresh rate ((100 Hz))
erasing/priming
addressing
sustaining
Slide 18
Influence of the surface on the plasma ignition by ion induced emission of
secondary electrons
i =
Number of emitted electrons
Number of ions on the surface
Front glass
MgO
Plasma
Vf 
D2  p  d

C  pd 
 ln

l (1 /  i  1) 
 ln(
2
MgO is the material with the highest Ne ~ 00.55
Slide 19
Tasks of the MgO protective layer
0
10
450
Effe
ectives gamma
Ignition voltage ((V)
Ne
Ne
400
350
300
250
200
150
-1
10
MgO; i = 0.5
Glas; i = 0.06
Glas,  i = 0.06
MgO,  i = 0.5
100
-2
10
0
10
20
30
p x d (Torr cm)
10
-1
-1
100
E / p (V Torr cm )
MgO protective layer causes
• a protection against sputtering
• a reduction of the ignition voltage
Slide 20
Stability
St
bilit
Temperature stability
Stability in suspension
Plasma stability
Color point stability
Sensitivity to oxidation
Solubility, surface potential
Resistance to sputtering
Photo-oxidation, reduction
Light output
Linearity
Efficiency
Saturation
Quantum yield QA, absorption A
Image quality
Image artifacts
Color space
Decay time 
Color point x, y
Environmental
En
ironmental compatibilit
compatibility
Energy efficiency
Toxicity
Quantum yield QA, absorption A
Chemical composition
Slide 21
VUV (PDPs) or electrons (CRTs)
Visible light
1 µm
Plasma Display
• High
g absorption
p
A under VUV excitation,, i.e.,, band g
gap
p EG ~ 6 – 8 eV
• High quantum yield QA under VUV excitation, i.e., Eu2+, Tb3+, Mn2+, Eu3+
• High light output LO = QA*A
• VUV stability
Slide 22
CRT phosphors (sulphides)
PDP phosphors (oxides)
1,0
1,0
0,8
Relative intensity
R
0,6
0,4
0,2
0,0
400
ZnS:Ag
450
Y2O2S:Eu
ZnS:Cu,Al,Au
500
550
600
650
Wavelength [nm]
700
750
0,6
0,4
0,2
0,0
400
BaMgAl10O177:Eu
Relative intensityy
0,8
450
(Y,Gd)BO3:Eu
Zn2SiO4:Mn
500
550
600
650
700
750
Wavelength [nm]
Light output
LO = QE* (1-R)
Energy efficiency
 = (1-rb)*t* hem /Eg
~ 15 - 20%
Energy efficiency
 = LO *N(hem)/N(habs)
~ 20%
Slide 23
Commercial CRT and PDP phosphors
Color
Bl
Blue
Green
Red
Blue
G
Green
Red
Chemical composition
Z SA
ZnS:Ag
ZnS:Cu
Y3(Al,Ga)5O12:Tb
Y2SiO5:Tb
Gd2O2S:Tb
YVO4:Eu
Y2O2S:Eu
(Y,Gd)(V,P)O4
BaMgAl10O17:Eu
Z 2SiO4:Mn
Zn
M
BaMgAl10O17:Eu,Mn
BaAl12O19:Mn
(Y Gd)BO3:Tb
(Y,Gd)BO
(Y,Gd)BO3:Eu
(Y,Gd)2O3:Eu
((Y,Gd)(V,P)O
, )( , ) 4:Eu
CRT
PDP
x
0 15
0.15
0.29
0.37
0 33
0.33
0.36
0.66
0.66
y
0 08
0.08
0.61
0.55
0 58
0.58
0.57
0.33
0.33
Problem areas
0.16
0.15
0 25
0.25
0.15
0.19
0 34
0.34
0.64
0.65
0.66
0.13
0.06
0 70
0.70
0.72
0.73
0 62
0.62
0.35
0.34
0.33
Burn-in
(stability)
M i artifacts
Motion
if
(decay time)
Color gamut
(color point)
Slide 24
Color space
Cathode ray tube (CRTs)
Color space is defined by the color points
of the p
phosphor
p
x
y
ZnS:Ag
0.15
0.08
ZnS:Cu,Al, Au
0.29
0.61
Y2O2S:Eu
0.66
0.33
Plasma displays (PDPs)
Gas filling: Ne, 3 - 15% Xe
R d neon li
Red
lines reduce
d
color
l purity
it off
blue and green phosphor
x
y
BaMgAl10O17:Eu
0.15
0.06
Zn2SiO4:Mn
0.25
0.70
(Y,Gd)BO3:Eu
0.65
0.35
Slide 25
11.8 Red PDP Phosphors
4
4.0x10
4f 7 2p-1
6
4f 5d
-1
1
Wave num
mber [cm ]
4
3.5x10
4
3.0x10
4
2 5x10
2.5x10
4
2.0x10
5
D3
5
D2
D1
5
D0
4
5
1.5x10
4
1.0x10
3
5.0x10
0.0
7
F6
5
4
3
2
1
0
Eu3+
4f6
8
S7/2
Eu2+
4f7
Eu2+ phosphors
E
h h
Transition: 4f65d1  4f7 (bands)
Position depends
p
on the crystal
y
field
 ~ 1 µs
Eu3+ phosphors
5D  7F (lines)
T
Transition:
iti
)
0
J (li
Inversion symmetry (S6, D3d)
Magnetic dipole transition 5D0 - 7F1
J = 0, ± 1 (J = 0  J = 0 forbidden)
MeBO3:Eu (calcite, vaterite)
 ~ 8 - 16 ms
No inversion symmetry
Electric dipole transition 5D0 -7F2,4
J  6 (Jbeginning = 0  J = 2, 4, 6)
Y2O3:Eu (bixbyite), Y(V,P)O4:Eu (xenotime)
 ~ 2 - 5 ms
Slide 26
Emission spectra and color points
7
D0 - F1
5
7
D0 - F 2
5
7
D0 - F3
Intensity
5
5
7
D0 - F4
Phopshor
(Y,Gd)BO3:Eu
(Y,Gd)BO3:Eu 0.640
0.360
Y2O3:Eu
Y2O3:Eu
0.641
0.344
YVO4:Eu
YVO4:Eu
0 645
0.645
0 343
0.343
Y2O2S:Eu
0.650
0.342
Y2O2S:Eu
600
650
700
Color point x, y
750
Wavelength [nm]
Color saturation: Y2O2S:Eu > YVO4:Eu > Y2O3:Eu > (Y,Gd)BO
(Y Gd)BO3:Eu
Slide 27
Excitation spectra and VUV light output of Eu3+-phosphors
Phosphor
14
1,4
Light output LO
147 nm 172 nm
1,2
Lig
ght output
1,0
((Y,Gd)BO
) 3:Eu
Y2O3:Eu
0,8
YVO4:Eu
0,6
04
0,4
Y2O2S:Eu
0,2
0,0
150
200
250
((Y,Gd)BO
, ) 3:Eu 0.78
0.75
Y2O3:Eu
0.60
0.69
YVO4:Eu
0 41
0.41
0.50
0 50
Y2O2S:Eu
0.26
0.32
300
Wavelength [nm]
Effi i
Efficiency
Phosphor
Band gap EG
(Y,Gd)BO3:Eu Y2O3:Eu
7 5 eV
7.5
5 6 eV
5.6
YVO4:Eu
5 0 eV
5.0
Y2O2S:Eu
4 4 eV
4.4
Slide 28
Decay time of Eu3+-phosphors
Norma
alised emissio
on intensity
1
GDBO3:Eu
(Y,Gd)BO3:Eu
(Y,Lu)BO3:Eu
Y(V,P)O4:Eu
(Y,Gd)2O3:Eu
0,1
0,01
1E-3
Decay
y time 1/10 [[ms]]
(254 nm excitation)
Y2O2S:Eu
1.0
Y2O3:Eu
2.5
YVO4:Eu
3.5
(Y Gd)BO3:Eu 8.5
(Y,Gd)BO
85
Phosphor
p
1E-4
1E-5
0
5
10
15
20
25
30
35
40
t [ms]
Decay time decreases with increasing deviation of the inversion symmetry of the
lattice site of Eu3+
 Relaxation of selection rules!
Slide 29
Local symmetry of Y3+ and Eu3+ in YBO3 (vaterite)
Platz A
Platz B
(J. Solid State Chem. 128 (1997) 261-266)
• Location A: Slight deviation from the S6 symmetry (C3)
• Location B: Strong deviation from the S6 symmetry ( (C3)
 5D0 - 7F2,4 emission is observed due to the deviation of the S6 symmetry
Slide 30
Emission spectra of LnBO3:Eu (vaterite)
Emissiion intensity
y [a.u.]
1,0
LuBO
u O3:Eu
u
YBO3:Eu
0,8
GdBO3:Eu
0,6
0,4
0,2
0,0
550
600
650
Wavelength [nm]
700
750
585 nm
594 nm
612, 627 nm
650 - 680 nm
690 - 720 nm
5D
0
5D
0
5D
0
5D
0
5D
0
- 7F0
- 7F1
- 7F2
- 7F3
- 7F4
Cation
Lu
Y
Gd
Eu
*for CN= 6
Radius* [Å]
1.00
1.04
1 08
1.08
1.09
Color point shifts from orange to red in the series Gd3+, Y3+, Lu3+
Distortion depends on r[(Eu3+) - r(Me3+)]
Slide 31
Color point of (Y,Gd)BO3:Eu3+
0,37
10 kV
254 nm
y
0,36
2 kV
172 nm
0,35
Feldman equation:
q
R = 0.046*U5/3/ [µm]
(Y Gd)BO3:Eu = 5.2
(Y,Gd)BO
5 2 g/cm3
147 nm
0,34
0,33

10 kV
R~ 500 nm
2 kV
R ~ 30 nm
0,32
0,60
0,61
0,62
0,63
0,64
0,65
0,66
x
Color point as a function of excitation energy
• Charge-transfer excitation
254 nm  x = 0.638, y = 0.360
• Band excitation
147 nm  x = 0.646, y = 0.349
Slide 32
Penetration depth of VUV radiation in matter
R ~ 1.5 µm
254 nm corresponds ~ 10 kV
R < 0.1 µ
µm
147 nm corresponds
p
~ 1 kV
Small excitation volume
 PDP phosphors are highly charged:
• Saturation
S t
ti
• Strong aging
• Surface layer of the particles must be pure phase and highly crystalline
Slide 33
Emission spectra of (Y,Gd)BO3:Eu
Cathodoluminescence
2 kV
10 kV
0,5
0,0
500
600
700
Wellenlänge [nm]
254 nm
172 nm
147 nm
1,0
Intensitä
ät
Intensitätt
1,0
Photoluminescence
0,5
0,0
500
600
700
Wellenlänge
g [[nm]]
Emission spectrum = f(excitation energy)
Slide 34
Color points of Eu3+-phosphors
L BO3:Eu
LuBO
E
7
1,0
7
F1
Emission inten
nsity [a.u.]
Emission inte
ensity [a.u.]
1,0
C OE
CaO:Eu
0,8
0,6
0,4
0,2
7
F2
7
F2
0,8
0,6
0,4
0,2
7
F4
F4
0,0
0,0
200
300
400
500
600
Wavelength [nm]
Trigonal, D3d symmetry
x = 0.61,
0 61 y = 0.38
0 38
700
800
200
300
400
500
600
700
Wavelength [nm]
Cubic, Oh symmetry
Cation vacancies
x = 0.64
0 64 , y = 00.33
33
Slide 35
800
Emission spectra and decay times of Mn2+- and Tb3+-phosphors
Mn2+-phosphors
p p
Zn2SiO4:Mn x = 0.249, y = 0.700
BaAl12O19:Mn x = 0.204, y = 0.717
0,8
0,6
0,4
LaPO4:Tb x = 0.352, y = 0.580
YBO3:Tb x = 0.338, y = 0.615
0,8
0,6
0,4
0,2
0,2
0,0
,
400
1,0
Emisssion intensity [a.u.]
1,0
Tb3+-phosphors
p p
0,0
450
500
550
600
650
700
Wavelength [nm]
Host lattice
1/10 [ms]
Zn2SiO4
5 - 40
BaAl12O19
5 - 40
BaMgAl10O17
5 - 40
1/10 = f(Mn
f(M 2+-concentration)
i )
Host lattice
LaPO4
CeMgAl11O19
YBO3
1/10 = f(host
f(h lattice)
l i )
1/10 [ms]
55
5.5
7.0
8.5
Slide 36
Color saturation
Mn2+-phosphors
yy- coordinate: 0.69 - 0.73
Zn2SiO4:Mn
YBO3:Tb
Tb3+-phosphors
y coordinate : 0.58
y0 58 - 0.62
0 62
Tb3+ has emission-line
multiplets at 590 and 620 nm
Slide 37
Spectra of the green PDP-pixels with Zn2SiO4:Mn
3.5% Xe
P116 3.5% Xe, ZSM
x=0.338, y=0.619
1,0
Emission intensity [[a.u.]
1,0
Emission intensity [[a.u.]
10% Xe
0,8
0,6
0,4
0,8
0,6
0,4
0,2
0,2
0,0
400
P183 10 % Xe, ZSM
x=0.233, y=0.686
500
600
Wavelength [nm]
700
File: ColourPoints of green PDPs
Zn2SiO4:Mn
• as a powder
• in PDP 10% Xe
• in
i PDP 3.5%
3 5% Xe
X
800
0,0
400
500
600
Wavelength [nm]
700
800
CIE1931 color p
point x,, y
0.25, 0.70
0.23, 0.69
0 34 0.62
0.34,
0 62
similar
i il to
t CRT
Slide 38
Spectra of the green PDP-pixels with (Y,Gd)BO3:Tb
3.5 % Xe
0,8
0,6
0,4
0,2
0,0
0
0
400
P249 10% Xe, YGBT
x=0.346 , y=0.595
1,0
P206 3.5% Xe, YBT
x=0.391 , y=0.534
1,0
10 % Xe
0,8
0,6
0,4
0,2
500
600
700
Wavelength [nm]
( , ) 3:Tb
(Y,Gd)BO
• as a powder
• in PDP 10% Xe
• in
i PDP 3.5%
3 5% Xe
X
800
0,0
0
0
400
500
600
Wavelength [nm]
700
800
CIE 1931 color p
point x. y
0.34, 0.62
0.35, 0.60
similar to CRT
0 39 0.53
0.39,
0 53
Slide 39
Phosphors in the system MeO-MgO-Al2O3
Construction of the intermediate layer
Me = Ba (1.34 Å)
Å
• BaMgAl10O17
• BaMg3Al14O25
BAM
-alumina
-alumina
Me = Sr (1.12 Å)
SAM
• SrMgAl
g 10O17
-alumina

• Sr2MgAl22O36 = SrMgAl10O17 + SrAl12O19
(-alumina + magnetoplumbite)
magnetoplumbite
-alumina
Me = Ca (0.99 Å)
CAM
• CaMgAl14O23
magnetoplumbite
• CaMg2Al16O27
magnetoplumbite
• CaMgAl10O17
-alumina
(unstable  magnetoplumbite)
Slide 40
S
Structure
off B
BaMgAl
M Al10O17
Localization of the europium
• Eu2+
Intermediate layers
• Eu3+
Spinel blocks
Potential secondary phases
• Al2O3
• BaAl
B Al2O4
• MgAl2O4
• EuAl11O18
• EuAlO3
• EuMgAl11O19
• Ba0.75Al11O17.25
• ….
Unit cell
Spinel
p
block MgAl
g 10O16
Intermediate layer
y BaO
Spinel block MgAl10O16
Intermediate layer BaO
S i l block
Spinel
bl k MgAl
M Al10O16
Isostructural to -alumina
 alumina NaAl11O17
Slide 41
S
Structure
off BaMgAl
A 10O17
L
Layer
structure
t t
Ba2+ environment
B
i
t
Ba2+(Eu2+) is nine-coordinate (tri-capped trigonal prism D3h)
 Relative small crystal field splitting  Blue emission band
Slide 42
Thermodynamic stability of -alumina
Conduction layer thickness M12k
4,9
Structural influence of the cations
in the interlayer
Rb
4,8
ß-alumina
4,7
Ba
Na
4,6
K
Ag
Pb
4,5
Sr
La
4,4
Nd
magnetoplumbite
Ca
4,3
1,1
1,2
1,3
1,4
1,5
Ionic radius [A]
Stability limit of -alumina phase lies at M12k > 4.6 Å
Eu2+ (r9 = 1.17 Å) is smaller than Sr2+ (r9 = 1.26 Å)
Thus: Eu2+-ion incorporation destabilizes the ß-alumina phase
Incorporation of large cations stabilizes the ß-alumina phase (Rb+, K+)
Slide 43
1,6
Luminescence spectra of BaMgAl10O17:Eu2+
Emission spectra as a
f
function
ti off excitation
it ti energy
Efficiency and reflection
1,0
Quantum yield QE
10
1,0
Excitation at 147 nm
Emiss
sion intensity
0,8
0,8
0,6
Light output LO = QE(1
QE(1-R)
R)
04
0,4
0,2
Reflection R
0,0
150
200
Wavelength [nm]
250
300
0,6
0,4
,
0,2
0,0
400
450
500
550
Wavelength [nm]
VUV absorption
bso p o and
d high
g quantum
qu u yield
y e d close
c ose to
o 100
00 %
Half-width of the emission band increases with the excitation energy
Slide 44
Color point: Influence of the Eu2+-concentration
Cation
• Ba2+
• Sr2+
• Ca2+
• Eu2+
Radius [Å]
1.34
1.12
0.99
1.09
BAM:x%Eu2+
• 1%
• 10%
• 15%
• 50%
x, y
0.152, 0.052
0 151 0.060
0.151,
0 060
0.151, 0.067
0.144, 0.111
0 12
0,12
Color coordinates
BAM:50% Eu
0,11
0,10
,
0,09
y 0,08
BAM:15% Eu
0,07
BAM:10% Eu
0,06
BAM:1% Eu
0,05
0,14
x
0,15
0,16
Green shift of the color point by increasing the Eu2+ concentration  Incorporation of Eu2+
destabilizes the BAM phase and leads to the formation of BaAl2O4:Eu
Slide 45
Color point: Influence of the excitation energy
147 nm
0,10
0,09
0 08
0,08
y
172 nm
2 kV
254 nm
0,07
0,06
Feldman equation
eq ation
R = 0.046*U5/3/ [µm]
10 kV
0,05
0,14
x
0,15
0,16
254 nm exc. x = 0.146, y = 0.068
~ 10 kV electron (400 nm)
Activator excitation  high penetration depth
147 nm exc. x = 0.140, y = 0.098
~ 2 kV electron (30 nm)
Band excitation  low penetration depth
Slide 46
Cathodoluminescence of BaMgAl10O17:Eu2+
2 kV excitation (surface)
10 kV excitation (volume)
1,0
1,0
2+
2+
Ba0.75Al11O17.25:Eu
0,8
0,8
0,6
0,6
0,4
0,4
0,2
0,2
0,0
400
500
Wavelength [nm]
600
0,0
400
BaAl2O4:Eu
500
600
Wavelength [nm]
The secondary phase BaAl2O4:Eu makes itself noticeable in the emission spectrum
Slide 47
Photoluminescence of BaMgAl10O17:Eu2+
147 nm excitation (surface)
254 nm excitation (volume)
1,0
1,0
2+
0,8
BaAl2O4:Eu
0,8
2+
0,6
0,6
0,4
0,4
0,2
0,2
0,0
400
0,0
400
500
Wavelength [nm]
600
BaAl2O4:Eu
500
600
Wavelength [nm]
Slide 48
BaMgAl10O17:Eu2+: Stability enhancement by particle coating
Excitation spectra of
uncoated powderer
uncoated
1,0
Light outpu
ut LO = QE*(1-R)
1,0
Light outputt LO = QE*(1-R)
Excitation spectra of
coated powder
0,8
0,6
0,4
BAM uncoated, 2h 500°C, air
0,2
BAM coated
0,8
0,6
0,4
BAM coated, 2h 500°C, air
0,2
00
0,0
00
0,0
150
200
250
300
350
Wavelength [nm]
150
200
250
300
Wavelength [nm]
Particle coating consists of an inert material that acts as a barrier for
a) Oxygen
No thermal degradation
b) 74 nm (147 nm) radiation
Reduced photodegradation
M
Materials:
i l Al2O3, AlPO4, Ca
C 2P2O7, SiO2, MgO
M O
Slide 49
350
Comparison of CRTs and PDPs (Stand 2008)
PDP-TV
80 cm - 750 cm
(32" - 300
(32
300"))
CRT-TV
max. 90 cm
(max. 36")
36 )
Luminance
(1% white display)
100 - 150 Cd/m2
100 - 130 Cd/m2
Peak luminance
(white display)
1000 Cd/m
Cd/ 2
500 Cd/m 2
Efficiencyy
3 – 5 lm/W
2 - 3 lm/W
Power consumption
in typical TV operation
150 - 300 W
200 - 300 W
Lifetime
> 30000 h
Weight
20 - 30 kg (42’’)
> 30000 h
 80 kg (36")
Thickness
< 10 cm
 60 cm (36")
Display diagonal
Slide 50
Future measures to improve the image quality of PDPs
Gas discharge
• Higher Xe partial pressure (higher driving voltage)
• Optimization of the surfaces (materials with a high -coefficient)
Cell geometry and optics
• Improving
p
g the conversion of ggenerated VUV p
photons
• Improving the light out-coupling to the front plate (reflector layers)
• Increasing the contrast: doping of screen’s glass, color filters, black matrix
Phosphors
• Improving the photostability of the blue phosphors
• Shortening of the decay of the green phosphors
• Improvement of the color point and shortening of the decay of the red phosphor
• Increasing the contrast of colored phosphors
Slide 51

11. Gas Discharge Displays

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