11. Gas Discharge Displays

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1 11. Gas Discharge Displays Content 11.1 Technologies for Flat Displays 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 Red PDP Phosphors 11.9 Green PDP Phosphors Blue PDP Phosphors Status and Outlook Slide 1

2 11.1 Technologies for Flat Displays Technology Efficiency Max. size Areas of application Organic EL 2 lm/w 10 Automobiles, mobile phones Inorg. EL 1 lm/w 17 Instrument displays FED 5 lm/w 17 LCD 4 lm/w 65 Laptops, monitors, LCD TV PALC 4 lm/w LED Array 8-10 lm/w > 100 Billboards Projection TV 5 lm/w TV PDP 5 lm/w ~ 152 TV, scoreboards CRT 3 lm/w 36 TV, monitors Remark: Theoretical limit for white light ~ 300 lm/w opt. Energy efficiency of displays ~ 1-5% Slide 2

3 Gas Discharge Displays 11.1 Technologies for Flat Displays Properties Flat and large ( inch) Thin ~ 100 mm Lightweight ~ kg for 42-inch Large viewing angle ~ " HDTV-PDP No distortion Unaffected by external magnetic fields Slide 3

4 Emissive Display Types 11.1 Technologies for Flat Displays Technology CRT PDP Excitation source Electron beam Gas discharge Excitation energy kev 6-10 ev Gas pressure < 10-3 mbar mbar Xe/Ne Phosphors Sulfides Oxides Viewing angle > 160 > 160 Resolution EDTV UHTV 720 x 480 pixel 3840 x 2160 pixel (4K) Slide 4

5 Technologien Technologies für for flache Flat Bildschirme Displays Plasma displays 1929 Slide 5

6 11.2 Construction of Gas Discharge Displays Simplified 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

barrier ribs Conical structure TiO 2 -film as a

7 11.2 Construction of Gas Discharge Displays Structure of a plasma cell Glass back panel Structuring by barrier ribs Conical structure TiO 2 -film as a reflector Phosphor layer (with additives) U-shaped structure Slide 7

8 Preparation of the front plate 11.3 Manufacturing Process Slide 8

9 Preparation of the back plate 11.3 Manufacturing Process Slide 9

10 11.4 Light Generation in Plasma Displays Functional principle Visible light Visible light Front glass plate Gas discharge VUV VUV Rear glass plate ~ 200 µm Phosphor VUV light Noble gas discharge Slide 10

11 11.4 Light Generation in Plasma Displays Efficiency of light generation h display = h discharge. h UV. h phosphor. h out-coupling PDP-cell Xe 2 *- lamp Hg - lamp h Plasma 24 % 70 % 75 % h UV 40 % 90 % 98 % h Phosphor 20 % 25 % 44 % h Coupling out 50 % 90 % 98 % h Display 1.0 % 14 % 30 % Typ. light output 3 lm/w 40 lm/w 90 lm/w Slide 11

12 Emission intensity [a.u.] 11.4 Light Generation in Plasma Displays Light generation in Ne discharges Ne + e - Ne* + e - Ne* Ne + h (74 nm + vis.) 1,0 0,8 0,6 Ne* + Ar Ne + Ar + + e - Ne* + Xe Ne + Xe + + e - (Penning ionization) - Monochrome PDPs - Neon discharge lamps - Hg-discharge lamps with Ne-filling "neon lamps" 0,4 0,2 0, Wavelength [nm] Gas mixtures of Ne/Ar or Ne/Xe thus cause a reduction of the ignition voltage by the so-called Penning effect Slide 12

13 147 Wavelength / nm 172 Energy 11.4 Light Generation in Plasma Displays Light generation in Xe/Ne discharge High Pressure Xe( 1 S 0 ) + e - Xe( 3 P 1 ) + e - Xe( 3 P 2 ) + e - Xe** 2 nd Continuum 3 u + 1 u + 1 u 3P S 0 3P S 0 B A Xe** Xe( 3 P 1 ) + h (828 nm) Xe( 3 P 2 ) + h (823 nm) 1 st Continuum 1 g + 2 nd 1 st Continuum Resonance Line Xe( 3 P 2 ) Xe( 1 S 0 ) + h (147 nm) Resonance Line Low Pressure 1S S Internuclear Distance (Å) Xe( 3 P 1 ) + Xe( 1 S 0 ) + M Xe 2 *( 1 u+ ) + M / Xe( 3 P 2 ) + Xe( 1 S 0 ) + M Xe 2 *( 3 u+ ) + M X Xe 2 *( 3 u+ ) Xe 2 *( 1 g+ ) + h (150 nm) 2 Xe( 1 S 0 ) Xe 2 *( 1 u+ ) Xe 2 *( 1 g+ ) + h (172 nm) 2 Xe( 1 S 0 ) Slide 13

14 Emission intensity [a.u.] Relative proportion of radiation 11.4 Light Generation in Plasma Displays Light generation in Xe/Ne discharge 1,0 1, nm 0,8 0,6 20% Xe 0, nm 10% Xe 150 nm 0,4 1% Xe 0,010 0,2 0, Wavelength [nm] 0, Xenon partial pressure / mbar 50% Xe 2 *-excimer and 50% Xe* resonance emission at 25 mbar Xe partial pressure PDPs 2005: Xe percentage at 10-15% and 300 mbar total pressure, i.e., Xe 2 *-excimer radiation predominates Slide 14

15 Luminance (cd/m 2 ) Efficacy (lm/w) Sustainvoltage (V) 11.4 Light Generation in Plasma Displays Influence of Xe partial pressure mbar, 500 V, 50 khz Vsm Vf Xe-content (%) Xe-content (%) With the Xe pressure the efficiency and the ignition voltage increases Slide 15

16 11.4 Light Generation in Plasma Displays Dependence on the Xe/Ne partial pressure 100% Ne Ne/Xe 100% Xe Low ignition voltage ~ 300 V Visible emissions nm (Monochrome red) VUV emission 74 nm High ignition voltage ~ 2 kv No visible emission (color is defined by the phosphor) VUV emission 147, 150, 172 nm Slide 16

17 11.5 Operation of the Gas Discharge Dielectric barrier discharges Schematic operation of a PDP-cell Course of voltage and current Dielectric V negative glow negative glow 0 V 0 I 0 t Slide 17

18 Addressing the pixel 11.5 Operation of the Gas Discharge Each pixel has 2 n brightness levels By 8-bit addressing one obtains 2 8 = 256 brightness levels In a RGB-display there is therefore = 16.7 million colors available Frame: Will be specified by the refresh rate (100 Hz) erasing/priming addressing sustaining Slide 18

19 11.5 Operation of the Gas Discharge 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 Plasma Front glass MgO V f ln D 2 p d C p d ln(1/ 1) i 2 MgO is the material with the highest Ne ~ 0.5 Slide 19

20 Ignition voltage (V) Effectives gamma 11.5 Operation of the Gas Discharge Tasks of the MgO protective layer Ne 10 0 Ne Glas, i = 0.06 MgO, i = p x d (Torr cm) MgO protective layer causes a protection against sputtering a reduction of the ignition voltage 10-2 MgO; i = 0.5 Glas; i = E / p (V Torr -1 cm -1 ) Slide 20

21 11.6 Selection Criteria for Display Phosphors Stability Temperature stability Sensitivity to oxidation Stability in suspension Solubility, surface potential Plasma stability Resistance to sputtering Color point stability Photo-oxidation, reduction Light output Linearity Efficiency Image quality Image artifacts Color space Environmental compatibility Energy efficiency Toxicity Saturation Quantum yield QA, absorption A Decay time Color point x, y Quantum yield QA, absorption A Chemical composition Slide 21

11.6 Selection Criteria for Display Phosphors VUV (PDPs) or electrons (CRTs) Visible light 1 µm Plasma Display High absorption A under VUV excitation, i.

22 11.6 Selection Criteria for Display Phosphors VUV (PDPs) or electrons (CRTs) Visible light 1 µm Plasma Display High absorption A under VUV excitation, i.e., band gap E G ~ 6 8 ev High quantum yield QY under VUV excitation, i.e., Eu 2+, Tb 3+, Mn 2+, Eu 3+ High light output LO = QY*A VUV stability Slide 22

23 Relative intensity Relative intensity BaMgAl 10 O 17 :Eu 11.6 Selection Criteria for Display Phosphors CRT phosphors (sulphides) PDP phosphors (oxides) 1,0 1,0 0,8 0,8 0,6 0,6 0,4 0,4 0,2 ZnS:Ag Energy efficiency = (1-r b )* t * h em / E g ~ 15-20% ZnS:Cu,Al,Au 0, Wavelength [nm] Y 2 O 2 S:Eu 0,2 Zn 2 SiO 4 :Mn (Y,Gd)BO 3 :Eu 0, Wavelength [nm] Light output LO = QE* (1-R) Energy efficiency = LO *N(h em )/N(h abs ) ~ 20% Slide 23

24 11.7 Phosphors in CRTs and PDPs Commercial CRT and PDP phosphors Color Chemical composition x y Problem areas Blue ZnS:Ag Green ZnS:Cu Y 3 (Al,Ga) 5 O 12 :Tb Y 2 SiO 5 :Tb Gd 2 O 2 S:Tb CRT Red YVO 4 :Eu Y 2 O 2 S:Eu Blue (Y,Gd)(V,P)O Burn-in BaMgAl 10 O 17 :Eu (stability) Green Zn 2 SiO 4 :Mn Motion artifacts BaMgAl 10 O 17 :Eu,Mn (decay time) BaAl 12 O 19 :Mn (Y,Gd)BO 3 :Tb PDP Red (Y,Gd)BO 3 :Eu Color gamut (Y,Gd) 2 O 3 :Eu (color point) (Y,Gd)(V,P)O 4 :Eu Slide 24

25 Color space 11.7 Phosphors in CRTs and PDPs Cathode ray tube (CRTs) Color space is defined by the color points of the phosphor x y ZnS:Ag ZnS:Cu,Al, Au Y 2 O 2 S:Eu Plasma displays (PDPs) Gas filling: Ne, 3-15% Xe Red neon lines reduce color purity of blue and green phosphor x y BaMgAl 10 O 17 :Eu Zn 2 SiO 4 :Mn (Y,Gd)BO 3 :Eu Slide 25

J = 0, ± 1 (J = 0 J = 0 forbidden) MeBO 3 :Eu (calcite, vaterite) ~ 8-16 ms No inversion symmetry Electric dipole

26 11.8 Red PDP Phosphors Eu 2+ phosphors Transition: 4f 6 5d 1 4f 7 (bands) Position depends on the crystal field ~ 1 µs Eu 3+ phosphors Transition: 5 D 0 7 F J (lines) Inversion symmetry (S 6, D 3d ) Magnetic dipole transition 5 D 0-7 F 1 J = 0, ± 1 (J = 0 J = 0 forbidden) MeBO 3 :Eu (calcite, vaterite) ~ 8-16 ms No inversion symmetry Electric dipole transition 5 D 0-7 F 2,4 J 6 (J beginning = 0 J = 2, 4, 6) Y 2 O 3 :Eu (bixbyite), Y(V,P)O 4 :Eu (xenotime) ~ 2-5 ms Slide 26

27 Intensity Emission spectra and color points 11.8 Red PDP Phosphors 5 D 0-7 F 1 5 D 0-7 F 2 5 D 0-7 F 3 5 D 0-7 F 4 Phopshor Color point x, y (Y,Gd)BO 3 :Eu (Y,Gd)BO 3 :Eu Y 2 O 3 :Eu Y 2 O 3 :Eu YVO 4 :Eu YVO 4 :Eu Y 2 O 2 S:Eu Y 2 O 2 S:Eu Wavelength [nm] Color saturation: Y 2 O 2 S:Eu > YVO 4 :Eu > Y 2 O 3 :Eu > (Y,Gd)BO 3 :Eu Slide 27

28 Light output 11.8 Red PDP Phosphors Excitation spectra and VUV light output of Eu 3+ -phosphors 1,4 1,2 Phosphor Light output LO 147 nm 172 nm 1,0 (Y,Gd)BO 3 :Eu Y 2 O 3 :Eu (Y,Gd)BO 3 :Eu ,8 0,6 YVO 4 :Eu Y 2 O 3 :Eu ,4 0,2 0,0 Y 2 O 2 S:Eu YVO 4 :Eu Y 2 O 2 S:Eu Wavelength [nm] Efficiency Phosphor (Y,Gd)BO 3 :Eu Y 2 O 3 :Eu YVO 4 :Eu Y 2 O 2 S:Eu Band gap E G 7.5 ev 5.6 ev 5.0 ev 4.4 ev Slide 28

29 Normalised emission intensity Decay time of Eu 3+ -phosphors 11.8 Red PDP Phosphors 1 0,1 0,01 1E-3 1E-4 GDBO3:Eu (Y,Gd)BO3:Eu (Y,Lu)BO3:Eu Y(V,P)O4:Eu (Y,Gd)2O3:Eu Phosphor Decay time 1/10 [ms] (254 nm excitation) Y 2 O 2 S:Eu 1.0 Y 2 O 3 :Eu 2.5 YVO 4 :Eu 3.5 (Y,Gd)BO 3 :Eu 8.5 1E t [ms] Decay time decreases with increasing deviation of the inversion symmetry of the lattice site of Eu 3+ Relaxation of selection rules! Slide 29

30 11.8 Red PDP Phosphors Local symmetry of Y 3+ and Eu 3+ in YBO 3 (vaterite) Platz A Platz B (J. Solid State Chem. 128 (1997) ) Location A: Slight deviation from the S 6 symmetry (C 3 ) Location B: Strong deviation from the S 6 symmetry ( (C 3 ) 5 D 0-7 F 2,4 emission is observed due to the deviation of the S 6 symmetry Slide 30

31 Emission intensity [a.u.] Emission spectra of LnBO 3 :Eu (vaterite) 11.8 Red PDP Phosphors 1,0 0,8 0,6 LuBO 3 :Eu YBO 3 :Eu GdBO 3 :Eu 585 nm 5 D 0-7 F nm 5 D 0-7 F 1 612, 627 nm 5 D 0-7 F nm 5 D 0-7 F nm 5 D 0-7 F 4 0,4 0,2 0, Wavelength [nm] Cation Radius* [Å] Lu 1.00 Y 1.04 Gd 1.08 Eu 1.09 *for CN= 6 Color point shifts from orange to red in the series Gd 3+, Y 3+, Lu 3+ Distortion depends on r[(eu 3+ ) - r(me 3+ )] Slide 31

32 Color point of (Y,Gd)BO 3 :Eu Red PDP Phosphors y 0,37 0,36 0, nm 172 nm 10 kv 2 kv Feldman equation: R = 0.046*U 5/3 / [µm] (Y,Gd)BO 3 :Eu = 5.2 g/cm 3 0, nm 10 kv R~ 500 nm 0,33 2 kv R ~ 30 nm 0,32 0,60 0,61 0,62 0,63 0,64 0,65 0,66 Color point as a function of excitation energy Charge-transfer excitation 254 nm x = 0.638, y = Band excitation 147 nm x = 0.646, y = x Slide 32

33 11.8 Red PDP Phosphors Penetration depth of VUV radiation in matter R ~ 1.5 µm 254 nm corresponds ~ 10 kv R < 0.1 µm 147 nm corresponds ~ 1 kv Small excitation volume PDP phosphors are highly charged: Saturation Strong aging Surface layer of the particles must be pure phase and highly crystalline Slide 33

34 Intensität Intensität Emission spectra of (Y,Gd)BO 3 :Eu 11.8 Red PDP Phosphors Cathodoluminescence Photoluminescence 1,0 2 kv 10 kv 0,5 1,0 254 nm 172 nm 147 nm 0,5 0, Wellenlänge [nm] 0, Wellenlänge [nm] Emission spectrum = f(excitation energy) Slide 34

35 Emission intensity [a.u.] 7 F 1 Emission intensity [a.u.] 7 F 4 Color points of Eu 3+ -phosphors 11.8 Red PDP Phosphors LuBO 3 :Eu CaO:Eu 1,0 1,0 7 F 2 0,8 0,8 0,6 0,6 0,4 0,4 0,2 7 F 2 7 F 4 0,2 0, Wavelength [nm] 0, Wavelength [nm] Trigonal, D 3d symmetry x = 0.61, y = 0.38 Cubic, O h symmetry Cation vacancies x = 0.64, y = 0.33 Slide 35

36 Emission intensity [a.u.] Emission intensity [a.u.] 11.9 Green PDP Phosphors Emission spectra and decay times of Mn 2+ - and Tb 3+ -phosphors Mn 2+ -phosphors Tb 3+ -phosphors 1,0 Zn 2 SiO 4 :Mn x = 0.249, y = BaAl 12 O 19 :Mn x = 0.204, y = ,0 LaPO 4 :Tb x = 0.352, y = YBO 3 :Tb x = 0.338, y = ,8 0,8 0,6 0,6 0,4 0,4 0,2 0,2 0, Wavelength [nm] Host lattice 1/10 [ms] Zn 2 SiO BaAl 12 O BaMgAl 10 O /10 = f(mn 2+ -concentration) 0,0 Host lattice 1/10 [ms] LaPO CeMgAl 11 O YBO /10 = f(host lattice) Slide 36

37 11.9 Green PDP Phosphors Color saturation Mn 2+ -phosphors y- coordinate: Zn 2 SiO 4 :Mn YBO 3 :Tb Tb 3+ -phosphors y- coordinate : Tb 3+ has emission-line multiplets at 590 and 620 nm Slide 37

38 Emission intensity [a.u.] Emission intensity [a.u.] 11.9 Green PDP Phosphors Spectra of the green PDP-pixels with Zn 2 SiO 4 :Mn 1,0 0,8 3.5% Xe 10% Xe P % Xe, ZSM x=0.338, y= ,0 0,8 P % Xe, ZSM x=0.233, y= ,6 0,6 0,4 0,4 0,2 0,2 0, Wavelength [nm] File: ColourPoints of green PDPs 0, Wavelength [nm] File: ColourPoints of green PDPs Zn 2 SiO 4 :Mn CIE1931 color point x, y as a powder 0.25, 0.70 in PDP 10% Xe 0.23, 0.69 in PDP 3.5% Xe 0.34, 0.62 similar to CRT Slide 38

39 Emission intensity [a.u.] Emission intensity [a.u.] 11.9 Green PDP Phosphors Spectra of the green PDP-pixels with (Y,Gd)BO 3 :Tb 3.5 % Xe 10 % Xe 1,0 P % Xe, YBT x=0.391, y= ,0 P249 10% Xe, YGBT x=0.346, y= ,8 0,8 0,6 0,6 0,4 0,4 0,2 0,2 0, Wavelength [nm] 0, Wavelength [nm] File: ColourPoints of green PDPs (Y,Gd)BO 3 :Tb CIE 1931 color point x. y as a powder 0.34, 0.62 in PDP 10% Xe 0.35, 0.60 similar to CRT in PDP 3.5% Xe 0.39, 0.53 Slide 39

40 11.10 Blue PDP Phosphors Phosphors in the system MeO-MgO-Al 2 O 3 Construction of the intermediate layer Me = Ba (1.34 Å) BAM BaMgAl 10 O 17 -alumina BaMg 3 Al 14 O 25 -alumina magnetoplumbite -alumina Me = Sr (1.12 Å) SAM SrMgAl 10 O 17 -alumina Sr 2 MgAl 22 O 36 = SrMgAl 10 O 17 + SrAl 12 O 19 ( -alumina + magnetoplumbite) Me = Ca (0.99 Å) CAM CaMgAl 14 O 23 magnetoplumbite CaMg 2 Al 16 O 27 magnetoplumbite CaMgAl 10 O 17 -alumina (unstable magnetoplumbite) Slide 40

11.10 Blue PDP Phosphors Structure of BaMgAl 10 O 17 Unit cell Localization of the europium Eu 2+ Intermediate layers Eu 3+ Spinel blocks Potential secondary phases Al 2 O 3 BaAl 2 O 4 MgAl 2 O 4

41 11.10 Blue PDP Phosphors Structure of BaMgAl 10 O 17 Unit cell Localization of the europium Eu 2+ Intermediate layers Eu 3+ Spinel blocks Potential secondary phases Al 2 O 3 BaAl 2 O 4 MgAl 2 O 4 EuAl 11 O 18 EuAlO 3 EuMgAl 11 O 19 Ba 0.75 Al 11 O Spinel block MgAl 10 O 16 Intermediate layer BaO Spinel block MgAl 10 O 16 Intermediate layer BaO Spinel block MgAl 10 O 16 Isostructural to -alumina NaAl 11 O 17 Slide 41

42 Structure of BaMgAl 10 O Blue PDP Phosphors Layer structure Ba 2+ environment Ba 2+ (Eu 2+ ) is nine-coordinate (tri-capped trigonal prism D 3h ) Relative small crystal field splitting Blue emission band Slide 42

43 Thermodynamic stability of -alumina Blue PDP Phosphors 4,9 Structural influence of the cations in the interlayer Conduction layer thickness M 12k 4,8 4,7 4,6 4,5 4,4 4,3 Na La ß-alumina Ba Ag Pb Sr magnetoplumbite Rb K Nd Ca 1,1 1,2 1,3 1,4 1,5 1,6 Ionic radius [A] Stability limit of -alumina phase lies at M 12k > 4.6 Å Eu 2+ (r 9 = 1.17 Å) is smaller than Sr 2+ (r 9 = 1.26 Å) Thus: Eu 2+ -ion incorporation destabilizes the ß-alumina phase Incorporation of large cations stabilizes the ß-alumina phase (Rb +, K + ) Slide 43

44 Emission intensity Blue PDP Phosphors Luminescence spectra of BaMgAl 10 O 17 :Eu 2+ Efficiency and reflection Emission spectra as a function of excitation energy 1,0 0,8 0,6 0,4 Quantum yield QE Light output LO = QE(1-R) 1,0 0,8 0,6 0,4 Excitation at 147 nm Excitation at 172 nm Excitation at 254 nm 0,2 Reflection R 0,2 0, Wavelength [nm] 0, Wavelength [nm] VUV absorption and high quantum yield close to 100 % Half-width of the emission band increases with the excitation energy Slide 44

45 11.10 Blue PDP Phosphors Color point: Influence of the Eu 2+ -concentration Cation Radius [Å] Ba Sr Ca Eu y 0,12 0,11 0,10 0,09 0,08 Color coordinates BAM:50% Eu BAM:15% Eu BAM:x%Eu 2+ x, y 1% 0.152, % 0.151, % 0.151, % 0.144, ,07 0,06 0,05 BAM:10% Eu BAM:1% Eu 0,14 0,15 0,16 x Green shift of the color point by increasing the Eu 2+ concentration Incorporation of Eu 2+ destabilizes the BAM phase and leads to the formation of BaAl 2 O 4 :Eu Slide 45

46 11.10 Blue PDP Phosphors Color point: Influence of the excitation energy 0, nm 0,09 y 0,08 0,07 2 kv 172 nm 254 nm Feldman equation R = 0.046*U 5/3 / [µm] 0,06 10 kv 0,05 0,14 0,15 0,16 x 254 nm exc. x = 0.146, y = ~ 10 kv electron (400 nm) Activator excitation high penetration depth 147 nm exc. x = 0.140, y = ~ 2 kv electron (30 nm) Band excitation low penetration depth Slide 46

47 11.10 Blue PDP Phosphors Cathodoluminescence of BaMgAl 10 O 17 :Eu 2+ 2 kv excitation (surface) 10 kv excitation (volume) 1,0 0,8 Ba 0.75 Al 11 O :Eu 2+ 1,0 0,8 BaAl 2 O 4 :Eu 2+ 0,6 0,6 0,4 0,4 0,2 0,2 0, Wavelength [nm] 0, Wavelength [nm] The secondary phase BaAl 2 O 4 :Eu makes itself noticeable in the emission spectrum Slide 47

48 11.10 Blue PDP Phosphors Photoluminescence of BaMgAl 10 O 17 :Eu nm excitation (surface) 254 nm excitation (volume) 1,0 1,0 0,8 0,6 BaAl 2 O 4 :Eu 2+ 0,8 0,6 BaAl 2 O 4 :Eu 2+ 0,4 0,4 0,2 0,2 0, Wavelength [nm] 0, Wavelength [nm] Slide 48

49 Light output LO = QE*(1-R) Light output LO = QE*(1-R) Blue PDP Phosphors BaMgAl 10 O 17 :Eu 2+ : Stability enhancement by particle coating Excitation spectra of uncoated powderer Excitation spectra of coated powder 1,0 uncoated 1,0 BAM coated 0,8 0,8 0,6 0,6 0,4 BAM uncoated, 2h 500 C, air 0,4 BAM coated, 2h 500 C, air 0,2 0,2 0, 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 0,0 Wavelength [nm] Materials: Al 2 O 3, AlPO 4, Ca 2 P 2 O 7, SiO 2, MgO Slide 49

50 11.11 Status and Outlook Comparison of CRTs and PDPs (Stand 2008) Display diagonal Luminance (1% white display) Peak luminance (white display) PDP-TV 80 cm cm (32" - 300") CRT-TV max. 90 cm (max. 36") Cd/m Cd/m Cd/m Cd/m 2 Efficiency 3 5 lm/w 2-3 lm/w Power consumption in typical TV operation W W Lifetime > h > h Weight kg (42 ) 80 kg (36") Thickness < 10 cm 60 cm (36") Slide 50

51 11.11 Status and Outlook 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 the conversion of generated VUV 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

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