VUV Phosphors for Plasma Display Panels and Excimer Discharge Lamps Thomas Jüstel University of Applied Sciences Münster Materials Valley Workshop January 20 th, 2011 Prof. Dr. T. Jüstel, University of Applied Sciences Münster, Germany Slide 1
Plasma Display Panels 1929 Prof. Dr. T. Jüstel, University of Applied Sciences Münster, Germany Slide 2
Outlines 1. Introduction 2. Xe and Xe/Ne Discharges 3. Inorganic luminescent materials 4. Phosphors for plasma display panels 5. Phosphors for Xe 2 * discharge lamps 6. Application areas 7. Conclusions Prof. Dr. T. Jüstel, University of Applied Sciences Münster, Germany Slide 3
1. Introduction - Light Generation in PDPs and Discharge Lamps - PDP pixel Lamp burner UV UV Electrode Dielectric Phosphor Discharge cone Xe/Ne excimer discharge Xe 2 * excimer discharge Prof. Dr. T. Jüstel, University of Applied Sciences Münster, Germany Slide 4
Radiation generation (Xe) Xe + e - Xe( 3 P 1 ) + e - 2. Xe and Xe/Ne Discharges Xe( 3 P 2 ) + e - Xe** 172 Wave elength / nm High Pressure 2 nd Continuum rgy Ene 1 + 1 u 3P 1 + 1 S 0 3P 2 + 1 S 0 Xe** Xe( 3 P 1 ) + h (828 nm) 2 nd 1 st Resonance Xe( 3 Line Continuum P 2 ) + h (823 nm) Xe( 3 P 1 ) Xe + h (147 nm) 147 1 st Continuum Resonance Line 3 u + u 1 g + B A 1S + 1 0 S 0 X Xe( 3 P 1 ) + Xe + M Xe 2 * + M Low Pressure 2 3 4 5 6 7 Internuclear Distanc Xe 2 * 2 Xe + h (150 nm and 172 nm) Application of 50 90% Ne reduces discharge ignition voltage plasma displays Prof. Dr. T. Jüstel, University of Applied Sciences Münster, Germany Slide 5
Radiation generation (Ne) 2. Xe and Xe/Ne Discharges 10 1,0 Ne + e - Ne* + e - Ne* Ne + h (74 nm + vis.) Ne* + Ar Ne + Ar + +e - Ne* + Xe Ne + Xe + + e - (Penning Ionisation) monochrome plasma displays Emissions sintensität [a.u.] 0,6 0,2 0,0 400 500 600 700 800 Wellenlänge [nm] Prof. Dr. T. Jüstel, University of Applied Sciences Münster, Germany Slide 6
Features 2. Xe and Xe/Ne Discharges No Hg (EU legislation issue?) Noble gas discharge chemically inert Instant light Arbitrary design GLS-look-a-like, lik tubular, flat, co-axial, etc. T-independent light output Long lifetime even for fast switching cycle scheme Emission mainly in the Vacuum Ultraviolet (VUV) Intensity [a.u.] 147 150 172 Resonance e Line 1 st Continu um 2 nd Continu uum Prof. Dr. T. Jüstel, University of Applied Sciences Münster, Germany Slide 7
Features 2. Xe and Xe/Ne Discharges Emission in ntensity [a..u.] Xe 2 * Hg 1,0 Tb 3+ Phosphor Xe emission QD Xe = 0.32 0,6 0,2 Hg emission QD Hg = 0.47 0,0 100 200 300 400 500 600 700 Burner / cell efficiency = discharge * QD * QE * escape QD(Hg) = 0.47 QD(Xe 2 *) = 0.32 Hg discharge: = 30% Xe 2 * discharge = 20% Problem areas of Xe/Ne excimer discharge driven light sources + displays Large quantum deficit (QD) reduces wall plug efficiency VUV radiation causes severe photodegradation Prof. Dr. T. Jüstel, University of Applied Sciences Münster, Germany Slide 8
3. Inorganic Luminescent Materials Requirements on VUV phosphors Very good crystallinity it High purity (99,99% or better) Homogeneous distribution of activator and sensitiser ions Emission Excitation Absorption process related to Heat Heat Heat Optical centres (impurities) activators (A) sensitisers (S) S ET defects (D) A D Host lattice (band edge) Energy transfer often occur prior to emission process! Emission ET A Heat ET A Heat Prof. Dr. T. Jüstel, University of Applied Sciences Münster, Germany Slide 9 ET
3. Inorganic Luminescent Materials Fundamental aspects: Simplified energy level schemes of selected RE ions 4f 7 5d 1 254 nm Line emission from m -1 ] En nergy [c 4.0x10 4 5d 1 4f 7 2p -1 3.5x10 4 3.0x10 4 2.5x10 4 2.0x10 4 1.5x10 4 1.0x10 4 0.5x10 4 2 F 7/2 5 D 3 5 D 2 5 D 1 5 D 0 7 F 6 5 4 3 2 1 0 4f 6 5d 1 0.0 2 F 8 5/2 S 7/2 Eu 3+ Eu 2+ [Xe] 6 I 7/ 2 6 P 7/2 Pr 3+ Nd 3+ Sm 3+ 7/2 Eu 3+ (Eu 2+ ) Gd 3+ 5 Tb 3+ D 3 Dy 3+ 5 D 4 Ho 3+ Er 3+ Tm 3+ Yb 3+ 0 2 1 3 4 5 Pr 3+ 8 Nd 3+ S 7/2 Ce 3+ Gd 3+ Tb 3+ Yb 4f 1 4f 6 4f 7 4f 7 4f 8 7 F 6 Band emission from Ce 3+ Eu 2+ Yb 2+ (Tl +, Pb 2+, Sb 3+,Bi 3+ ) Prof. Dr. T. Jüstel, University of Applied Sciences Münster, Germany Slide 10
3. Inorganic Luminescent Materials Fundamental aspects: Energy distance between the 4f n and 4f n-1 5d 1 configuration Free ion Centroid Shift Crystal field Stokes Shift ] gy [cm -1 Energ 4f n-1 5d 1 c cfs 4f n Free ion: Eu 2+ Ce 3+ Pr 3+ Nd 3+ 4f n-1 5d 1 level @ 34000 cm -1 50000 cm -1 62000 cm -1 70000 cm -1 Only RE ions and some main group element ions are applicable in luminescent materials showing UV emission Prof. Dr. T. Jüstel, University of Applied Sciences Münster, Germany Slide 11
4. Phosphors for Plasma Display Panels Quality Issues Production compatibility Temperature stability Suspension stability Performance Brightness Color point stability Image quality Motion artefacts Color gamut Environment Energy efficiency Toxicity Sensitivity towards oxidation Solubility, surface potential QE, particle morphology, saturation VUV Stability Decay time Color point (stability) QE, particle morphology Chemical composition Prof. Dr. T. Jüstel, University of Applied Sciences Münster, Germany Slide 12
Em mission inten nsity [a.u.] 4. Phosphors for Plasma Display Panels - Efficient Red Emitting Phosphor - Y 3+ 2 O 3 :Eu (Y,Gd)BO 3+ 3 :Eu Low-pressure Hg discharges Xe excimer discharges 254 nm 172 nm 1,0 5 D0-7 1,0 F 5 0 J D0 0-7 F J 0,6 0,2 7 F 0-5 D 2 7 F 7 F 0-5 0-5 D 3 D 1 Em mission inten nsity (a.u.) 0,6 0,2 0,0 150 200 250 300 350 400 450 500 550 600 650 700 750 0,0 150 200 250 300 350 400 450 500 550 600 650 700 750 Prof. Dr. T. Jüstel, University of Applied Sciences Münster, Germany Slide 13
4. Phosphors for Plasma Display Panels Colour points and decay times Phosphor x y [ms] Zn 2 SiO 4 :Mn BaMgAl 10 O 17 :Eu 0.148 0.068 < 1 Y(V,P)O BAM:Mn 4 0.161 0.133 <1 (Y,Gd)BO 3 :Tb BaMgAl 10 O 17 :Mn 0.140 0.695 12 Zn 2 SiO 4 :Mn 0.233 0.702 10 (Y,Gd)BO 3 :Tb 0.324 0.615 8 LaPO 4 :Ce,Tb 0.350 0.582 3 (Y,Gd)BO 3 :Eu 0.636 0.357 8 Y 2 O 3 :Eu 0.640 0.346 2.5 Y(Y,P)O 4:Eu 0.657 0.330 1 Y(V,P)O 4 LaPO 4 :CeTb BAM:Eu (Y,Gd)BO 3 :Eu Y 2 O 3 :Eu Y(V,P)O 4:Eu Prof. Dr. T. Jüstel, University of Applied Sciences Münster, Germany Slide 14
4. Phosphors for Plasma Display Panels VUV phosphors Presently applied shortcoming Novel materials based on host lattices with suitable band edge BaMgAl 10 O 17 :Eu Zn 2 SiO 4 :Mn (Y,Gd)BO 3 :Eu stability decay time color point BaMg 3 Al 14 O 25 :Eu Sr 6 BP 5 O 20 :Eu BaAl 2 Si 2 O 8 :Eu CaAl 2 O 4 :Eu LaPO 4 :Tm BaAl 12 O 19 :Mn BaMg 3 Al 14 O 25 :Mn 400 500 600 700 (Y,Gd) 2 SiO 5 :Eu Prof. Dr. T. Jüstel, University of Applied Sciences Münster, Germany Slide 15
5. Phosphors for Xe 2 * Discharge Lamps Intensity [a.u.] 147 150 172 Resonance Line 1 st Continuum 2 nd Continuu m 190-700 nm Phosphor layer (quartz) glass Features Potential application areas Phosphor layer Discharge efficiency ~ 65% Photocopier lamps RGB or B/W Hg free LCD Backlighting RGB Fast switching cycles Medical skin treatment UV-A/B Temperature independent Photochemistry UV-A/B/C Dimmable Disinfection UV-C High lifetime Ultra pure water - Mainly VUV emission Surface/wafer cleaning - Prof. Dr. T. Jüstel, University of Applied Sciences Münster, Germany Slide 16
5. Phosphors for Xe 2 * Discharge Lamps VUV phosphors for white Xe 2 * discharge lamps Spectrum of Osram Planon BaMgAl 10 O 17 :Eu 80 lm/w 0,006 opt g 10 17 opt. LaPO 4 :Ce,Tb 500 lm/w opt. 0,004 (Y,Gd)BO 3 :Tb 530 lm/w opt. (Y,Gd)BO 3 :Eu (Y,Gd) 2 O 3 :Eu 275 lm/w opt. 290 lm/w opt. 0,002 0,001001 p Emission intens sity [a.u.] 0,005 0,003 BaMgAl 10 O 17 :Eu LaPO 4 :Ce,Tb x = 0325 0.325 y = 0.297 Tc = 5920 K LE = 282 lm/w Ra 14 = 87 (Y,Gd)BO 3 :Eu Luminous efficiency < 50 lm/w el. 0,000 400 500 600 700 Challenges related to VUV phosphors for Xe 2 * discharge lamps a) Lamp efficacy Down conversion phosphors b) VUV stability Particle coatings (MgO or Al 2 O 3 ) c) Color point stability Optimised blue phosphor d) Novel application areas UV phosphors p Prof. Dr. T. Jüstel, University of Applied Sciences Münster, Germany Slide 17
5. Phosphors for Xe 2 * Discharge Lamps Down conversion phosphors: Single ion mechanism on Pr 3+ UV band emission 1,0 1 S 0-3 F 4 1 S 1 0 - G 4 1 S 0-1 I 6 Emission spectrum Excitation spectrum UV line emission i 0,6 3 P 0-3 H 4 3 P 0-3 H 6, 3 F 2 Blue emission 02 0,2 0,0 100 200 300 400 500 600 700 Red emission First fluorides: YF 3 :Pr und NaYF 4 :Pr (J.L. Sommerdijk et al., J. Lumin. 8 (1974) 341) 1 S 0-3 P 1, 1 I 6 at 407 nm 3 P 0-3 H 6, 3 F 2 at 615 nm Oxidic phosphors: Host lattices with Ln 3+ sites having high coordination number SrAl 12OO 19 :Pr, LaMgB 5 O 10 :Pr,and LaB 3 O 6 :Pr (A. Srivastava et al., GE) Prof. Dr. T. Jüstel, University of Applied Sciences Münster, Germany Slide 18
5. Phosphors for Xe 2 * Discharge Lamps Down conversion phosphors: Pair mechanism in Gd 3+ -Eu 3+ or Gd 3+ -Er 3+ Discovered by A. Meijerink et al. in 2000 Internal quantum efficiency about 195% in LiGdF 4 External quantum efficiency about 30 35% at 202 nm due to competitive host lattice absorption, which does not result in luminescence (low transfer efficiency!) Gd Gd** + Eu Eu* Gd* + Eu Eu* 202 nm CR ET Gd** Eu* + Gd* Eu + h Gd + Eu* Eu + h Prof. Dr. T. Jüstel, University of Applied Sciences Münster, Germany Slide 19
5. Phosphors for Xe 2 * Discharge Lamps VUV Stability Sample C 1s O 1s Si 2p Y 3p3/2 Xe 3d5/2 Phosphor degrades due to VUV radiation Direct contact to the discharge Low penetration depth of VUV radiation Xe 2 */+ adheres to phosphor surface, electron take-up is difficult as phosphor surface is too electronegative (low PZC, e.g. silicates or SiO 2 ) Xe 2+ is stabilised by strong Lewis acids (SbF 5, SiO 2 ) and absorbs in the UV-A/B and red spectral range Y-phosphor (as made) 1.1 70.2 28.7 < 0.05 < 0.1 SiO 2 coated Y-phosphor after 0.3 68.7 28.4 < 0.05 2.6 100 h lamp operation (all values in atom-%) Consequences No silicate phosphors! Coating by alkaline li materials Al 2 O 3 or MgO as protective coating a)jacs 102 (1980) 2856 b) E. Riedel, Modern Inorganic chemistry Prof. Dr. T. Jüstel, University of Applied Sciences Münster, Germany Slide 20 20
5. Phosphors for Xe 2 * Discharge Lamps Color point stability (blue phosphor) Improved BaMgAl 10 O 17 :Eu,(Mn) by application Mg 2+ excess during synthesis (J.-P. Cuif, Rhodia, PGS 2005) Alternative materials BaAl 2 Si 2 O 8 :Eu 435 nm (Chem. Mater. 2006) LaPO 4 :Tm 454 nm blended with BaMgAl 10 O 17 :Eu (J. Luminescence 2005) emission inte ensity [a.u.] Normalized 1,0 0,6 0,2 a b (Y,Gd)BO 3 :Eu b Zn 2 SiO 4 :Mn c BaMgAl 10 O 17 :Eu standard d BaMgAl 10 O 17 :Eu improved d a c.u.] ion intensity [a. Emiss 1,0 0,6 0,2 Excitation spectrum Emission spectrum 0,0 100 200 300 400 500 600 700 800 Sample V1382 00 0,0 0 200 400 600 800 1000 Operation time [h] Prof. Dr. T. Jüstel, University of Applied Sciences Münster, Germany Slide 21
5. Phosphors for Xe 2 * Discharge Lamps VUV UV Phosphors Host lattices and activators UV-C UV-B UV-A 100 nm 200 nm 280 nm 320 nm 400 nm Host lattices Fluorides Phosphates Borates Silicates Aluminates Suitable activators Nd 3+,Tl + Pb 2+, Pr 3+, Bi 3+ Gd 3+, Bi 3+, Pr 3+, Ce 3+ Tm 3+,Pb 2+,Ce 3+ Prof. Dr. T. Jüstel, University of Applied Sciences Münster, Germany Slide 22 22
5. Phosphors for Xe 2 * Discharge Lamps UV-A Phosphors y Relative intensit 1,0 0,6 0,2 0,0 BaSi 2 O 5 :Pb Sr 2 MgSi 2 O 7 :Pb 172 nm LaMgAl 11 O 19 :Ce YPO 4 :Ce 150 200 250 300 350 Relative intensity 1,0 0,6 0,2 Lu3Al5O12:Tm(1%) 1700 C Emission spectrum LuAG:Tm 1700 C Excitation spectrum LuAG:Tm 1700 C Reflection spectrum 0,0 0 100 200 300 400 500 600 700 800 Sample: AK001a UV-A emitting phosphors for UV-C excitation (LP Hg discharge lamps) VUV Efficiency: LaMgAl 11 O 19 :Ce > YPO 4 :Ce ~ BaSi 2 O 5 :Pb > Sr 2 MgSi 2 O 7 :Pb 100 90 80 70 60 50 40 30 20 10 Diffuse reflection (%) UV-A emitting phosphor for VUV excitation Lu 3 Al 5 O 12 :Tm Emission @ 292 and 352 nm, exc. max. at 170 nm Prof. Dr. T. Jüstel, University of Applied Sciences Münster, Germany Slide 23
5. Phosphors for Xe 2 * Discharge Lamps UV-B Phosphors Gd 3+ emitter Sensitisation by the host lattice (suitable band gap!) Example: YAl 3 (BO 3 ) 4 :Gd (NEC patent US2005/001024) Relativ ve intensity YAl 3 (BO 3 ) 4 :10%Gd Band gap ~ 172 nm 1,0 6 P -> 8 S 7/2 7/2 0,6 0,2 8 S 7/2 -> 6 I J Sensitisation by co-dopants Bi 3+ large lattice position (e.g. La 3+ ) required Ce 3+ suitable 4f5d state pos. required Pr 3+ suitable 4f5d state pos. required suitable 4f5d state pos. required Nd 3+ Example: GdPO 4 :Nd Relative e intensity 00 0,0 100 200 300 400 500 600 700 1,0 0,6 Band gap YAl 3 (BO 3 ) 4 :Gd(10%)Pr(1%) 4f 2 -> 4f1 5d 1 6 P 7/2 -> 8 S 7/2 (Philips patent EP06112503) 0,2 0,0 100 200 300 400 500 600 700 Prof. Dr. T. Jüstel, University of Applied Sciences Münster, Germany Slide 24
5. Phosphors for Xe 2 * Discharge Lamps UV-B Phosphors Gd 3+ emitter LaMgAl 11 O 19 :30%Gd 3+ QE(172 nm) close to 100%! Light output [ab bsolute values] 1,0 0,6 0,2 0,0 LaMgAl 11 O 19 :Gd vs LaPO 4 :Ce (NP806) LO NP806 LO TR037-05 05 LO TR036-05 exc.slit 2 x 3000 m 150 200 250 300 350 400 Emission inte ensity (Counts) LaMgAl 11 O 19 :Gd vs LaPO 4 :Ce (NP806) 2,4x10 5 Emission spectrum NP806 2,2x10 5 Emission spectrum TR3705 Emission spectrum TR3605 2,0x10 5 1,8x10 5 1,6x10 5 1,4x10 5 1,2x10 5 1,0x10 5 8,0x10 4 6,0x10 4 emis.slit slit 2 x 250 m 40x10 4,0x10 4 monitored at 312 nm (LAP:Ce at 320 nm) 2,0x10 4 exc.slit 2 x 3000 m emis.slit 2 x 250 m excitation at 160 nm 0,0 200 250 300 350 400 Prof. Dr. T. Jüstel, University of Applied Sciences Münster, Germany Slide 25
5. Phosphors for Xe 2 * Discharge Lamps UV-C Phosphors - Bi 3+ and Pb 2+ emitter Normalised intensity 1,0 DIN5031-10 LuPO 4 :Bi YPO 4 :Bi 0,6 0,2 ntensity Normalised i 1,0 DIN5031-10 CSOPb CaSO 4 :Pb 0,6 0,2 (Ca,Mg)SO 4 :Pb SrSiO 3 :Pb 0,0 200 220 240 260 280 300 320 340 Wavelength (nm) 0,0 200 220 240 260 280 300 320 340 (Ca,Mg)SO 4 :Pb, SrSiO 3 :Pb sensitivity towards water, Xe up-take (Y,Lu)PO 4 :Bi good chemical stability + high VUV efficiency Prof. Dr. T. Jüstel, University of Applied Sciences Münster, Germany Slide 26
5. Phosphors for Xe 2 * Discharge Lamps VUV to VUV down converting phosphors - Nd 3+ emitter YPO 4 :Nd LiYF 4 :Nd 1,0 Emission spectrum 1,0 Emission spectrum Excitation spectrum Excitation spectrum tensity No ormalised int 06 0,6 02 0,2 Relative int tensity 06 0,6 02 0,2 0,0 120 140 160 180 200 220 240 260 280 300 320 340 360 380 400 Wavelength (nm) 0,0 120 140 160 180 200 220 240 260 280 300 320 340 360 380 400 Emission maxima at 190 + 240 + 278 nm Prof. Dr. T. Jüstel, University of Applied Sciences Münster, Germany Slide 27 27
5. Phosphors for Xe 2 * Discharge Lamps Phosphor converted Xe 2 * excimer discharge lamp for disinfection 1,0 Germicidal Action Curve Requires UV-C emitting phosphor with a high conversion efficiency and a large 0,6 integral overlap with germicidal action curve e.g. Pr 3+ or Bi 3+ activated materials nsity (a.u.) Emission inte 0,2 Lamp spectrum of YAlO 3 :Pr Phosphor max [nm] GAC overlap [%] YPO 4 :Pr 233 78 YPO 4 :Bi 241 71 YAlO 3 :Pr 245 71 YBO 3 :Pr 263 61 Line @ 265 100 Line @ 311 0 intensity [a.u.] Emission 0,0 200 250 300 350 400 1,0 Germicidal Action Curve 0,6 0,2 Lamp Spectrum YBO 3 :Pr 00 0,0 200 250 300 350 400 Prof. Dr. T. Jüstel, University of Applied Sciences Münster, Germany Slide 28
6. Application Areas Lamps without phosphor Lamps with VUV phosphors solely 172 nm radiation spectrum can be defined by the phosphor in accordance to application area Application area Required emission Embodiments from Hg-free CFL-i White (tricolour blend) - Backlighting of LCDs White or UV-A Osram, Hitachi, Stanley Photocopier / scanner White or UV-A NEC, Ushio Purification VUV Heraeus, Ushio, Radium Disinfection UV-C - Tanning UV-A - Photochemistry UV-B or UV-A - XERADEX (Radium) Prof. Dr. T. Jüstel, University of Applied Sciences Münster, Germany Slide 29
6. Application Areas Xe Discharge lamps - Copiers and scanners Color Tetrachromatic phosphor blend B/W single phosphor BaMgAl 10 O 17 :Eu LaPO 4 :Ce,Tb Zn 2 SiO 4 :Mn LaPO 4 :Ce,Tb (Y,Gd)BO 3 :Eu Prof. Dr. T. Jüstel, University of Applied Sciences Münster, Germany Slide 30
6. Application Areas Xe Discharge lamps - LCD Backlighting 25000 LAP 20000 Intensity [a.u.] 15000 10000 BAM YGB 5000 0 400 450 500 550 600 650 700 750 800 Tricolor blend BaMgAl 10 O 17 :Eu 38 % LaPO 4 :Ce,Tb 38 % (Y,Gd)BO 3:Eu 24 % Lamp specifications Color point x = 0.290, y = 0.276 CCT = 9570 K R a = 89 Prof. Dr. T. Jüstel, University of Applied Sciences Münster, Germany Slide 31
6. Applications Areas - UV Radiation VUV UV-C UV-B UV-A 100 nm 200 nm 280 nm 320 nm 400 nm 12.5-6.9 ev 6.2 4.5 ev 4.5-3.9 ev 3.9 3.1 ev Cleavage of H 2 O and O 2 into radicals Excitation of C=C bonds Vitamine D production Photocatalytic reactions Ozone formation Cleavage of C-C, C-H, C-O bonds Excitation of nucleobases Cleavage of O 3, ClO 2 and H 2 O 2 Transcription of repair enzymes Melanosome formation (skin) Melanine oxidation (skin) Decomposition of organic pigments Activation of photocatalytical pigments Waver cleaning Disinfection of air, H 2O Treatment of skin Water and air purification and surfaces diseases, e.g. psoriasis @ TiO 2 photocatalyst, form. Photochemistry of OH. and O 2. radicals Photochemistry Tanning Tanning Photochemistry H 2 O 2 production in-situ Prof. Dr. T. Jüstel, University of Applied Sciences Münster, Germany Slide 32
Xe 2 * Discharge lamps for disinfection and Purification purposes 6. Application Areas Intensity [a.u.] Resonan nce Line 1 st Con ntinuum convert to 190-200 nm ntinuum 2 nd Co 147 172 convert to 200-280 nm Xe excimer emission spectrum Absorp ption coeffic cient [m -1 ] 10 8 Xenon Excimer 10 7 H 2 O 10 6 10 5 10 4 10 3 10 2 10 1 10 0 150 160 170 180 190 200 to improve penetration depth 10-8 10-7 10-6 10-5 10-4 10-3 10-2 10-1 10 0 Penet tration dep pth [m] Rel. effi iciency/abs sorption 1.0 Disinfection efficiency (DIN 5031-10) 0.8 0.6 0.4 0.2 0.0 200 220 240 260 280 300 320 to improve GAC overlap Prof. Dr. T. Jüstel, University of Applied Sciences Münster, Germany Slide 33
6. Application Areas Phosphor converted Xe 2 * excimer discharge lamp Requires development and optimization 1,0 Germicidal Action Curve Lamp spectrum of YAlO 3 :Pr of UV-C phosphors with a large GAC overlap 0,6 e.g. Pr 3+ or Bi 3+ activated phosphors LaPO 4 :Pr 225 nm KYF 4 :Pr 232 nm YPO 4 :Pr YPO 4 :Bi YAlO 3:Pr KY 3 F 10 :Pr LuBO 3 :Pr YBO 3:Pr Y 2 SiO 5 :Pr 233 nm 241 nm 245 nm 249 nm 257 nm 261 nm 270 nm Best practice UV-C phosphor p so far YPO 4:Bi Lamp efficiency 30% Intensity (a.u.) 0,2 00 0,0 200 250 300 350 Prof. Dr. T. Jüstel, University of Applied Sciences Münster, Germany Slide 34
7. Conclusions VUV phosphors as luminescent converters for Xe(Ne) discharges UV Ce 3+, Pr 3+, Nd 3+, Gd 3+, Tm 3+ Tl +, Pb 2+, Bi 3+ Blue Eu 2+, Ce 3+ Bi 3+ Green Tb 3+ Mn 2+ Red Eu 3+ Mn 2+, Mn 4+ Plasma display panels Long-term stability of phosphors with redox active activators is an issue Phosphor h blends as a trade-off between color point and efficiency i Red phosphor with a deep red color point is still required (Mn 4+?) Xe Excimer discharge lamps Luminous efficiency limited to 40 50 lm/w Down conversion phosphors are not within immediate reach Niche products: Photocopying, surface cleaning, backlighting, etc. Novel UV phosphors might open attractive application areas for Xe 2 * lamps UV-A phosphor with a high VUV efficiency is LaMgAl 11 O 19 :Ce Gd 3+ activated UV-B phosphors can be sensitised via host lattice or Nd 3+, Bi 3+ LuAG as a host lattice yields stable and efficient UV phosphors (Gd 3+,Tm 3+ ) YPO 4 :Bi and YPO 4 :Nd are the most efficient UV-C and VUV phosphors so far Prof. Dr. T. Jüstel, University of Applied Sciences Münster, Germany Slide 35
Acknowledgement Research Group Tailored Optical Materials Dr. Helga Bettentrup, Hendrik Busskamp, Danuta Dutczak, Linda Eickhoff, David Enseling, Rolf Gerdes, Benjamin Herden, Jagoda Kuc, Stephanie Möller, Dr. Julian Plewa, Tatjana Rat, Dr. Dominik Uhlich Suppliers of high puritiy Rare Earth Compounds Thanks to you for your kind attention.. Prof. Dr. T. Jüstel, University of Applied Sciences Münster, Germany Slide 36