Plagiarism Protection by Luminescent Substances - Prof. Dr. Thomas Jüstel & Dr. David Enseling Research Group Tailored Optical Materials - FH ...
←
→
Page content transcription
If your browser does not render page correctly, please read the page content below
Plagiarism Protection by Luminescent Substances Prof. Dr. Thomas Jüstel & Dr. David Enseling Research Group March 1869 March 2019 Tailored Optical Materials March 25th, 2019
To my Person
CV
• University Bochum (1987 - 1994) Coordination Chemistry
• Max-Planck Institute Mülheim (1995) Electrochemistry
• Philips Research Aachen (1995 - 2004) Luminescence, Solid State Chemistry
• Münster University of Applied Sciences
(since 2004) Inorg. Chemistry, Functional Materials
• Dean of Department
„Chemical Engineering CIW“ (since 2013)
Teaching
Inorganic Chemistry
Solid state chemistry
Coordination chemistry
Bioinorganic chemistry
Material Science
Functional materials
Luminescent materials
Material characterisation
Incoherent Light Sources https://www.fh-muenster.de/juestel
2 27.03.2019
About 20% of the produced electrical energy is used for lighting (source: NASA)
in
Even almost 30 years after Germany‟s reunification
East and West Berlin can be diminished by lighting East Berlin
1961 Construction of the Berlin Wall Na lamps
1989 End of the Berlin Wall “The wind of change”
1990 Germany‟s reunification West Berlin
1993 Blue LED: (In,Ga)N Hg lamps
1996 White LED: Y3Al5O12:Ce
2014 White LED > 300 lm/W & Nobel price
2015 UNESCO Internatiol year of light
2018 LED dominates lighting business ”The light of change”
Outline Luminescent Substances (Pigments) • Definition • Some Fundamentals • Properties • Evolution of Light Sources • Conventional and Emerging Applications Plagiarism Protection by Luminescent Pigments • Status • Novel Ideas • Analytical Techniques for Detection of Markers • Summary & Outlook • Literature 4 27.03.2019
Definition
Luminescence
• Luminescence is a process that corresponds to emission of electromagnetic
radiation beyond thermal equilibrium (in excess to thermal radiation)
• It involves the processes called fluorescence, phosphorescence, and
afterglow Luminescence at different time scales (nanoseconds to hours)
Under daylight
Upon excitation by electrons or UV radiation
5 27.03.2019
Definition
Difference to Incandescence
Incandescence corresponds to emission from solids in thermal equilibrium
„Black body radiation“, e.g. incandescent lamps, stars, hot surfaces, …..
3
4x10
3
3000K
3x10
Planck„s law (1900) 3
3x10
L e [W m nm ]
-1
c1 1 2x10
3
L e 5 c 2 /T
-2
2500K
λ 1
3
2x10
e
3
1x10
2000K
2
5x10
c1 = 3.741832.10-16 Wm2
0 200 400 600 800 1000 1200 1400 1600 1800 2000
c2 = 1.438786.10-2 Km W avelength [nm]
= Wavelength [m]
Wien‟s law
Le = Spectral irradiance
T = Temperature [K]
λ max T 2880 [μm K]
6 27.03.2019
Organic Luminescent Materials
Requirements and properties
• usually aromatic compounds (no C-H, N-H, or O-H bonds)
• low energy p p* transitions
• quantum yield increases with number of rings and degree of condensation
• fluorescence especially favored for rigid structures
• fluorescence increase for bounding to a metal complex formation
Examples of selected fluorescent compounds
Perylenes [Al(8-hydroxyquinolinate)3] [Ir(phenylpyridine)3]
O O
O O
N N
O O
O O
7 27.03.2019
Organic Luminescent Materials
Luminescence explained by Jablonski energy diagram
Molecules: Numerous vibrational energy levels for each electronic state!
S2, S1 = Singlet states
T1 = Triplet state
v = Vibrational levels
Lumogen F Orange ED240
Emission spectrum
1,0
Excitation spectrum
0,8
Relative intensity [a.u.]
0,6
0,4
0,2
0,0
300 400 500 600 700 800
Wavelength [nm]
8 27.03.2019
Inorganic Luminescent Materials Luminescent material = Host material + defects + dopants Host material Fluorides, Oxides, Nitrides, Sulphides, Selenides, ….. • Selection in accordance to requirements defined by the application area: Excitation energy, absorption strength, chemical environment, temperature, pressure and so on Defects Anion or cation defects, Interstitials • Afterglow (persistent luminescence) • Luminescence quenching (conc. and temperature dependent) • Stability reduction Dopants Cr3+, Mn4+, Tl+, Pb2+, Bi3+, Ce3+, Pr3+, Eu2+/3+, ..... • Selection and concentration depends on host lattice and application: Solubility, mobility, oxidation state stability, CT state location • Co-dopants to enhance absorption 9 27.03.2019
Inorganic Luminescent Materials
1 Host material + Dopants (RE-, TM- and s2- ions) 18
1 2
Zn 2
H 13 14 15 16 He 1
17 Zn
3 4 Groups 5 6 7 8 9 10
Li Be B C N O F Ne 2
11 12 13 14 15 16 17 18
Na Mg 3 4 5 6 7 8 9 10 11 12 Al Si P S Cl Ar 3
19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36
K Ca Sc Ti V Cr Mn Fe Co Ni Cu Zn Ga Ge As Se Br Kr 4
Periodes
37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54
Rb Sr Y Zr Nb Mo Tc Ru Rh Pd Ag Cd In Sn Sb Te I Xe 5
55 56 57 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86
Cs Ba La Hf Ta W Re Os Ir Pt Au Hg Tl Pb Bi Po At Rn 6
87 88 89 104 105 106 107 108 109 110 111 112
Fr Ra Ac Rf Db Sg Bh Hs Mt Ds Rg Cn 7
58 59 60 61 62 63 64 65 66 67 68 69 70 71
Ce Pr Nd Pm Sm Eu Gd Tb Dy Ho Er Tm Yb Lu 6
90 91 92 93 94 95 96 97 98 99 100 101 102 103
Th Pa U Np Pu Am Cm Bk Cf Es Fm Md No Lr 7
10 27.03.2019Inorganic Luminescent Materials
Requirements on efficient phosphors
• Highly crystalline particles
• High purity (99.99% or better)
• Homogeneous distribution of “impurities”
Excitation Emission
Heat Heat
Absorption process related to Heat
Optical centres (impurities)
• activators (A)
• sensitizers (S) A D
• defects (D) S
ET
• host material (band edge) ET ET
ET A
A
Energy transfer often occur
prior to emission process!
Emission Heat
Heat
11 27.03.2019Inorganic Luminescent Materials
A luminescent material (phosphor) converts absorbed energy into
electromagnetic radiation beyond thermal equilibrium
Host
• Coordination number and geometry
• Symmetry of activator sites
• Optical band gap
• Phonon spectrum Eu2+
Dopants, impurities, and defects Eu2+
• Concentration Eu2+
• Phase diagram and miscibility gaps Mn2+
VO
Particle surface
• Zeta-potential
• Surface area
• Coatings Light in- and outcoupling
Particle morphology
• Shape
• Particle size distribution
12 27.03.2019Inorganic Luminescent Materials
Morphology
• Nanoscale particles Molecular imaging, precursors
Optical marking
• µ-scale particles Lamps, LEDs, CRTs, PDPs,
Optical marking
• Large single crystals Scintillators, Laser
• Ceramics LEDs, scintillators, Laser
(cubic materials preferred)
1 nm 10 nm 100 nm 1 µm 10 µm 100 µm 1 mm 10 mm
13 27.03.2019Inorganic Luminescent Materials
Optical properties
Excitation and emission Decay curves of
spectrum of Mg2TiO4:Mn SrSi2N2O2:Eu
• Luminescence spectra Decay Measurement
Intensity [counts]
PRO-2009-AB-012 ex307nm T=100.00 K
1,0
656 nm T=150.00 K
• CIE colour point
PRO-2009-AB-012 mon656nm
1000 T=200.00 K
T=250.00 K
0,8 T=300.00 K
Relative intensity [a.u.]
T=350.00 K
• Luminous efficacy
T=400.00 K
T=450.00 K
0,6 100 T=500.00 K
• Colour point consistency 0,4
10
• Centroid wavelength 0,2
• Quantum yield 0,0
250 300 350 400 450 500 550 600 650 700 750 800
1
0 2000 4000 6000 8000 10000
time [ns]
Wavelength [nm]
• Decay curve T-dependent PL of selected Linearity of YAG:Ce
• Thermal quenching LMs upon 254 nm excitation and LiEuMo2O8
LiEuMo2O8
• Linearity
1,0
Ideal
Norm. emission integrals [a.u]
YAG:Ce U728
0,8
• Photochemical stability 0,6
• Absorption length 0,4
• ….. 0,2
0,0
0 100 200 300 400 500
Exc. density [W/mm2]
14 27.03.2019Inorganic Luminescent Materials
Luminescence spectra (excitation and emission)
Luminescence intensity depends Y2O3:Eu3+
Band 5 7
1,0 D0 - FJ
on excitation energy (wavelength) gap
Charge-
Emission intensity (a.u.)
Transfer
• 10 - 500 keV
0,8
Cathode or x-ray tubes
• 172 nm
0,6
Plasma displays
• 254 nm
0,4
Fluorescent lamps
• 400 nm
0,2 7 5
Near UV LEDs 7 5
F0 - D3
F0 - D2
7 5
F0 - D1
• 465 nm Blue LEDs 0,0
150 200 250 300 350 400 450 500 550 600 650 700 750
Wavelength [nm]
1,0
Normalised emission intensity
0,8
colour point
colour saturation
0,6
luminous efficacy
0,4
efficacy for biological
0,2
& chemical processes
0,0
300 400 500 600 700 800
Wavelength [nm]
15 27.03.2019Inorganic Luminescent Materials
Thermal quenching: Example red emitting LED material CaAlSiN3:Eu2+
2+
Mitsubishi CaAlSiN3:Eu (0.7%) Mitsubishi CaAlSiN3:Eu (0.7%)
2+
700000 70000000
350 K SSL-EX-037 CaAlSiN3:Eu
2+
400 K
Boltzmann fit of Data14_B
600000 450 K 60000000
Emission integral [counts]
500 K
Emission intensity [counts]
550 K
500000 50000000
600 K
Chip temperature range
650 K
400000 700 K
40000000
750 K
300000 30000000
200000 20000000
100000 10000000
0 0
500 600 700 800 300 400 500 600 700 800
Wavelength [nm] Temperature [K]
• All luminescent materials show a reduction of the photoluminescent quantum yield
and a colour point shift with increasing temperature
• Many luminescent materials are already quenched at room temperature
• LED phosphors must not quench at chip temperature: T1/2(CaAlSiN3:Eu) ~ 380 °C)
• T1/2 depends on chemical composition (band gap, defect density, phonons)
16 27.03.2019Inorganic Luminescent Materials
Decay curves and afterglow Material Decay time 1/e (254 nm)
1
BaMgAl10O17:Eu2+ 1.1 µs
(Y,Gd)BO3:Tb
Zn2SiO4:Mn Lu3Al5O12:Ce3+ 54 ns
(Y,Gd)BO3:Tb3+ 3.5 ms
Intensität
0,1
Zn2SiO4:Mn2+ 10 ms
0,01 Y3Al5O12:Ce3+ 65 ns
Y2O3:Eu3+ 1.0 ms
0,001
0 10 20 30 40 YVO4:Eu3+ 1.5 ms
t (ms)
(Y,Gd)BO3:Eu3+ 3.5 ms
Some observations
• Chemical composition of host and activator type determine decay time
• Decay time is a sensitive function of symmetry and chemical bond strengths
relaxation of quantum mechanical selection rules
• Afterglow is caused by energy transfer and defects
17 27.03.2019Luminescent Mat.: Simply Everywhere
Optical brightening Paint, pulp and paper, washing powder
Product anticounter feiting Bills, stamps, credit cards, tickets
Advertisement illumination Ne discharge lamps
Emergency illumination Emergency exits and signs, runways
Medical imaging and treatment x-ray converter films, scintillator crystals
Psoriasis and jaundice treatment
Dental ceramics
Astronomy EUV/VUV-Amplifier
Biochemistry Labels for DNA, RNA, proteins
Solar Cells Down-Shifter
Down-Converter
Up-Converter
Telecommunication NIR Amplifier
High energy physics Scintillator crystals, neutron detectors
18 27.03.2019Afterglow Materials
Afterglow pigments for glow purposes
• CaAl2O4:Eu,Nd 440 nm
• Sr2MgSi2O7:Eu,Dy 469 nm
• Sr4Al14O25:Eu,Dy 490 nm
• SrAl2O4:Eu,Dy 520 nm
• Sr2SiO4:Eu,Dy 570 nm
• Y2O2S:Eu,Ti,Mg 620 nm
• Sr3Al2O5Cl2:Eu 630 nm
• CaS:Eu,Tm 655 nm
• MgSiO3:Eu,Dy,Mn 660 nm
N329 in Oss (The Netherlands)
19 27.03.2019Afterglow Materials
Afterglow pigments for storage purposes
Process
1. Charging of the material, e.g. by high energy particles,
x-rays, or UV radiation
2. Stimulation of energy release to induce luminescence
• Thermal stimulated luminescence
(TSL: T >> 300 K)
• Photo stimulated luminescence
(PSL: Laser activation)
In a storage phosphor radiation energy is stored inside the material by traps
and the light of interest is not produced until the material is activated, either by
thermal or optical stimulation. Thus information on the radiation can be
obtained at a time later than the actual interaction.
20 27.03.2019Afterglow Materials Afterglow pigments for storage purposes Established materials • Ba(F,Br):Eu2+ PSL • RbBr:Tl+ PSL • SrS:Eu2+,Sm3+ PSL • Ba3(PO4)2:Eu2+ PSL • Ba2B5O9Br:Eu2+ PSL • Ba7Cl2F12:Eu2+ PSL • Ba12Cl5F19:Eu2+ PSL • Y2SiO5:Ce3+ PSL • Ba5SiO4Br6:Eu2+,Nb3+ PSL and TSL (150 °C) • Sr5(PO4)3Cl:Eu2+ PSL and TSL (157 °C) • Li6Gd0.5Y0.5(BO3)3:Eu3+ PSL and TSL (177 °C) • LiSr4(BO3)3:Ce3+ PSL and TSL (200 °C) • LiCaAlF6:Eu2+ PSL and TSL (240 °C) • LiYSiO4:Ce3+ PSL and TSL (260 °C) 21 27.03.2019
Conventional Application: Lighting
Luminescent materials are the basis of fluorescent light sources (LEDs & FLs)
Light yield of a light source Emission of lines or
narrow bands by
• Strongly dependent on emission spectrum Eu2+ Tb3+ Eu3+/Mn4+
• Optimum is at 555 nm
• V() = 683 lm/W (v = 100%)
Luminous efficacy [ lm/W ]
22 27.03.2019Evolution of Light Sources
Eu2+ , Tb3+, Eu3+ Ce3+, Eu2+ phosphors
1st Revolution 2nd Revolution 3rd Revolution 4th Revolution
First there ...put into a ...and made
...then the
was open glass more ...then the fire
fire was
fire... bulb... efficient... vanished and light
tamed...
only prevailed !
23 27.03.2019Evolution of Light Sources Source: Philips 24 27.03.2019
Evolution of Light Sources
19th century – „Solid State Lighting“
V() = Human Eye Sensitivity
1
Emission from solids in thermal
equilibrium „Black body radiation“
0.5
„2700 K Planck Spectrum“
Materials: C, Os, W
0 500 1000 1500 2000
Incandescent + halogen lamps
380 780 Wellenlänge in nm
Wavelength [nm]
25 27.03.2019Evolution of Light Sources
20th century – „Gas Discharge Lighting“
1,0
Tb3+
Emission from excited atoms/ions Eu3+
Relative intensity [a.u.]
0,8
0,6 Eu2+
Gas fillings: Hg, Na, Ne, Ar, Kr, Xe,
+ Luminescent materials 0,4
0,2
Fluorescent lamps + plasma displays
0,0
300 400 500 600 700 800
Wavelength [nm]
26 27.03.2019Evolution of Light Sources
21st century – „Solid State Lighting“ 1,0 Eu2+
(In,Ga)N
Normierte Intensität
0,8 LED Eu2+
Emission from solids due to
recombination of charge carriers 0,6
0,4
Materials: (Al,In,Ga)P, (Al,In,Ga)N,
0,2
polymers, Ir3+-complexes
0,0
300 400 500 600 700 800
Wellenlänge [nm]
Inorganic and Organic LEDs
+ - Metal cathode
Organic luminescent layer
Indium-Tin-Oxide Transparent organic
anode Hole transport layer
Glass
27 27.03.2019Phosphor Converted White LEDs
“Phosphor Converted” (pc) LED
Phos-
phor
Contact
Plastic
lens
(In,Ga)N-
semicon-
Gold wire ductor
In1-xGaxN Semiconductor
Heat sink (Cu)
1,0 CIE1931 x y
Normalised emission intensity
410 nm 0.173 0.026
419 nm 0.170 0.015
0,8 448 nm 0.156 0.035
455 nm 0.147 0.040
459 nm 0.143 0.047
0,6
462 nm 0.136 0.059
465 nm 0.132 0.071
468 nm 0.128 0.085
0,4
482 nm 0.092 0.216
0,2
0,0
400 450 500 550 600
Wavelength [nm]
28 27.03.2019Phosphor Converted White LEDs
1st Generation since 1996: Cool white LEDs
(In,Ga)N LED (Y,Gd)3Al5O12:Ce 70
1,0
60 Tc = 5270 K CRI = 82
Tc = 4490 K CRI = 79
Emission Intensity
0,8
Emission intensity
50
Tc = 4110 K CRI = 76
0,6 40 Tc = 3860 K CRI = 73
30
Tc = 3540 K CRI = 70
0,4
20
0,2
Blue Yellow 10
LED phosphor
0,0 0
400 450 500 550 600 650 700 750 800 400 500 600 700 800
Wavelength [nm] Wavelength [nm]
Status quo cool white phosphor converted LEDs @ 2019
• Yellow phosphors garnets: (Y,Gd,Tb)3Al5O12:Ce3+
ortho-silicates: (Ca,Sr,Ba)2SiO4:Eu2+
• LE ~ 300 lm/W (WPE > 80%) Element Y Gd Ce Al O (Y0,77Gd0,2Ce0,03)3Al5O12
Molar Mass (g/mol) 88,91 157,25 140,12 26,98 16,0 639,243
• CRI ~ 70 - 80 Coefficient 2,31 0,6 0,09 5 12
• CCT > 5000 K Mass fraction 32% 15% 2% 21% 30% 100%
29 27.03.2019Phosphor Converted White LEDs equal-lumen spectra
2nd Generation since 1996: Warm white LEDs 4.50E-04
4.00E-04
1.2
(In,Ga)N LED Y3Al5O12:CeRed phosphor 3.50E-04
JAZZ 3300K
BB 3300K
3.00E-04
1
W/nm
2.50E-04
0.8
2.00E-04
0.6 1.50E-04
1.00E-04
0.4
5.00E-05
0.2 0.00E+00
400 450 500 550 600 650
nm 700 750
0
0.025 1.2
400 450 500 550 600 650 700 750 nm 800
Wavelength [nm] 0.02
1.0
Warm white LEDs for indoor lighting 0.8
black body 3600 K
0.015
rad. flux, a.u.
rad. flux, a.u.
• Electric power consumption ~ 1 W fluorescent, CCT=3600 K 0.6
• Luminous efficacy ~ 100 lm/W 0.01
0.4
• Wall plug efficiency ~ 30 % 0.005
0.2
• Colour rendering index = 85 – 95
• Colour temperature 2700 – 4000 K 0
400 450 500 550 600 650 700 750
nm
800
0.0
30 27.03.2019Phosphor Converted White LEDs
Micropowders, (glass) ceramics, and crystals
Aluminates Ce3+ 1,0 SrS:Eu
(Y,Gd,Tb)3Al5O12:Ce (Sr0.75Ca0.25)S:Eu
(Sr0.5Ca0.5)S:Eu
Emission intensity [a.u.]
(Sr0.25Ca0.75)S:Eu
Lu3(Ga,Al)5O12:Ce 0,8
CaS:Eu
0,6
Sulphides Eu2+
0,4
(Ca,Sr)S:Eu
0,2
Oxides Eu2+ or Ce3+ 0,0
500 600 700 800
CaSc2O4:Ce,Mg Wavelength [nm]
(Ca,Sr,Ba)2SiO4:Eu Typical spectra of Eu2+ phosphors
(Ca,Sr,Ba)3SiO5:Eu 1,0
Normalised emission intensity
0,8
(Oxy)Nitrides Eu2+ or Ce3+
„2-5-8“
0,6
(Sr,Ca,Ba)2Si5N8:Eu
(Sr,Ca,Ba)Si2N2O2:Eu „1-2-2-2“ 0,4
(Ca,Sr)AlSiN3:Eu „1-1-1-3“ 0,2
La3Si6N11:Ce „3-6-11“
,ß-Si3-xAlxN4-xOx:Eu „SiAlONes“
0,0
300 400 500 600 700 800
Wavelength [nm]
31 27.03.2019Europium - The Magic of Colour
Eu2+ Phosphor Emission band bei [nm]
KMgF3:Eu 359 (Line)
SrB4O7:Eu 368
BaSO4:Eu 374
Sr2P2O7:Eu 420
BaMgAl10O17:Eu 453
SrSiAl2O3N:Eu 480
Sr4Al14O25:Eu 490
BaSi2N2O2:Eu 490
Ba2SiO4:Eu 505
SrAl2O4:Eu 520
SrGa2S4:Eu 535
SrSi2N2O2:Eu 541
Sr2SiO4:Eu 575
Ba2Si5N8:Eu 585
SrS:Eu 610
Sr2Si5N8:Eu 615
CaAlSiN3:Eu 650
CaS:Eu 655
SrSiN2:Eu 700
Trend for E: Fluorides < Oxides < Oxynitrides < Nitrides ~ Sulfides
32 27.03.2019Emerging: Human Centric Lighting
Spectra of white light sources
Tageslich
Day light Incandescent lamp Fluorescent lamp
t
Halogen lamp with IR filter Cool white LED Warm white LED
Day light Halogen Fluorescent LED lamp LED lamp
lamp lamp cool white warm white
Lux 100.000 500 500 500 500
UV 5% < 1% < 1% 0% 0%
VIS 60% 5% 90% 100% 90%
NIR 35% 95% 10% 0% 10%
33 27.03.2019Emerging: Plant Lighting
Lamp types in horticulture lighting
• Na vapour lamps
• Fluorescent lamps comprising blue and red luminescent materials
• Blue and red LEDs (+ far red LED)
• Blue LEDs + red (~ 660 nm) and far red (~700 nm) phosphors
Photoynthesis action curve
1,0
after McCree (DIN 5013-10)
Phytochrom red
Grass cultivated upon daylight Phytochrom far red
425 nm LED
or upon LED illumination 0,8 Mg28Ge7.5O38F10:Mn4+
Daylight (left vessel) and LED illumination Al2O3:Cr3+
(right vessel) Rel. action (%) (Ca,Sr)14Al10(Zn,Mg)6O35:Mn4+
0,6
0,4
0,2
0,0
Source: Semjon Reimer, FH Münster
400 500 600 700 800
Wavelength (nm)
34 27.03.2019Conventional: Displays
Cathode Ray Tubes EL Displays Plasma Displays
LCD Backlighting LED Displays Laser Displays
35 27.03.2019Conventional: Displays
Colour mixing in the Braun„s tube
(Cathode ray tube)
ZnS:Cu
Eu3+
1st generation YVO4:Eu3+
ZnS:Ag
2nd generation Y2O2S:Eu3+
36 27.03.2019Emerging: µ-LED Displays Micro-LED displays require inorganic nanoscale luminescent materials 465 nm µ-LEDs + • Green luminescent material • Red luminescent material 37 27.03.2019
Plagiarism Protection
State-of-the-Art
• Plenty of different luminescent pigments are used nowadays as
security element e.g. onto bank notes, stamps, documents and so on
• Only visual inspection instead of spectral measurements are mostly
used here
• But visual luminescent pigments are only a single out of ~ 30 different
security elements in Euro bank notes
Excitation @ 254 nm Excitation @ 366 nm
38 27.03.2019Plagiarism Protection
Today
• An increasing number of counterfeits of all kind of products congest
the markets worldwide
• In 2011 the German machinery and plant building industry lost around
7.9 billion € on counterfeits
• Unreasonable claims are the biggest problem besides losses by faked
products
• Manufacturers need a method to mark and
authenticate original products from fakes
especially for pharmaceutical and security
relevant products
Source: Tailorlux
39 27.03.2019Plagiarism Protection
Today: New requirements on security pigments
Complex products are also affected by fakes (www.plagiarius.com)
)
40 27.03.2019Plagiarism Protection
Today: New requirements on security pigments
• External marking in form of holograms, printed labels, or RFID chips
are visible and not permanent
• Security pigments should be integrated into product
• Inseparable combination of product and security pigment is possible
• No negative effect on product properties (due to low doping level)
• High stability against chemical and physical impacts
Source: Tailorlux
41 27.03.2019Plagiarism Protection Inorganic luminescent pigments as optical marker + Very stable against environmental conditions + High differentiability of the spectra (host lattice, activator) + Billions of individual security codes can be generated - More expensive than most organic luminescent materials - Difficult to read out spectra at low concentration level The security level of inorganic phosphors is very high due to the tremendous diversity and stability 42 27.03.2019
Plagiarism Protection
Inorganic luminescent pigments as optical marker
For security applications two kinds of inorganic rare earth doped luminescent
pigments are used:
• Down-shifting materials excitable by UV radiation
• Up-converting materials excitable by red or near IR radiation
Down-Conversion Up-Conversion
Line emittiers are mostly preferable due to the
possibilty to generate an optical fingerprint spectrum
43 27.03.2019Plagiarism Protection
Inorganic luminescent pigments as optical marker
Up-converter materials
+ Easy to detect (by red or NIR laser)
+ Visible in low concentrations
- Only a limited number of efficient systems available
- Up-converters can be purchased world-wide
- More and more counterfeiter working with up converting pigments
The security level of up-converting pigments is rather
low due to the limited number of well-known up-converters
Source: Tailorlux
44 27.03.2019Plagiarism Protection Inorganic luminescent pigments as optical marker Down-converter materials + Billions of individual combinations + Very high stability + High quantum yield + Excitable with a lower power density (no laser required) - Individual production possible - More expensive than simple inorganic phosphors The security level of inorganic down-converting pigments can be very high due to the enormous diversity of these materials 45 27.03.2019
Plagiarism Protection
Inorganic luminescent pigments as optical marker
To generate a wide range of different inorganic luminescent materials the
following is needed:
Special knowledge in solid state chemistry and pigment production
A lot of different raw materials at a high purity level ~ 99.99+%
Infrastructure for high temperature chemistry
Machinery for precise conditioning of luminescent pigments
Spectroscopic equipment to analyze finished luminescent materials
46 27.03.2019Plagiarism Protection
Inorganic luminescent pigments as optical marker
State-of-the-Art Innovation
• Marking by unknown inorganic • Marking by several unknown
luminescent material inorganic luminescent material or
by luminescent material with
• Relatively simple materials with
several optical features
specific visible spectra
• Quasi fingerprint spectra
• Simple analytical proof
• Complex analytical proof
Sample 1
Sample 2
Sample 3
Sample 4
Sample 5
Sample 6
Sample 7
Sample 8
Sample 9
Sample10
Sample 11
Sample 12
Sample 13
Sample 14
Optical marker present? Fingerprint correct?
47 27.03.2019Plagiarism Protection
Inorganic luminescent pigments as optical marker
Strategies for changing optical properties of luminescent materials:
• Specific activator and structure exchange cation types
• Specific activator exchange structure type
• Specific structure exchange activator
• Specific structure and activator add second activator
and add third activator
and so on
48 27.03.2019Plagiarism Protection
Inorganic luminescent pigments as optical marker
Specific activator and structure type exchange cation types
3+ 3+ 3+ 3+ 3+
LiLaW2O8:Eu NaLaW2O8:Eu KLaW2O8:Eu RbLaW2O8:Eu CsLaW2O8:Eu
Norm. intensity
600 650 600 650 600 650 600 650 600 650
Wavelength [nm]
49 27.03.2019Plagiarism Protection
Inorganic luminescent pigments as optical marker
Specific activator exchange structure type
Y2O3:Eu3+ YVO4:Eu3+ Y2O2S:Eu3+ YBO3:Eu3+ Y3Al5O12:Eu3+
Norm. Intensity
600 650 600 650 600 650 600 650 600 650
Wavelength [nm]
50 27.03.2019Plagiarism Protection
Inorganic luminescent pigments as optical marker
Specific structure type exchange activator
YPO4:Dy3+ YPO4:Pr3+ YPO4:Sm3+ YPO4:Eu3+ YPO4:Ho3+
Norm. Intensity
500 600 700 500 600 700 500 600 700 500 600 700 500 600 700
Wavelength [nm]
51 27.03.2019Plagiarism Protection
Inorganic luminescent pigments as optical marker
Specific structure type and activator add second activator
YPO4 doped with Sm3+ and a second trivalent rare earth activator
SmTb SmEu
1,0 Em Ex = 160nm Em Ex = 160nm
Ex Ex = 600nm 1,0 Em Ex = 601nm
Reflexion
0,8
0,8
Intensity [a.u.]
Intensity [a.u.]
0,6
0,6
0,4
0,4
0,2 0,2
0,0 0,0
200 300 400 500 600 700 800 200 300 400 500 600 700 800
Wavelength [nm] Wavelength [nm]
52 27.03.2019Plagiarism Protection
Inorganic luminescent pigments as optical marker
YPO4 comprising n different activator ions (each 1 atom-%), e.g. seven …..
1 2 n
Sm SmEu, SmTb, SmDy, SmHo, SmEr, SmTm
Eu EuTb, EuDy, EuHo, EuEr, EuTm
Tb TbDy, TbHo, TbEr, TbTm
Dy DyHo, DyEr, DyTm
Ho HoEr, HoTm
Er ErTm
Tm -
7 7 7
1 2 n
7 Variations for n = 1
28 Variations for n = 1 - 2
63 Variations for n = 1 - 3
98 Variations for n = 1 - 4
119 Variations for n = 1 - 5 without concentration profiles!
53 27.03.2019Plagiarism Protection
Inorganic luminescent pigments as optical marker
Complex analysis based on several optical centers possible by
• Excitation source: Broad vs. narrow (site elective spectroscopy)
• Environment: temperature, pressure, electrical fields, gases, ….
• Time: Immediate vs. delayed measurements
120000
120000
Ex= 254 nm 160 nm Anregung 1,0 nach 10 µs
100000 Ex= 450 nm 100000
25 °C nach 10 ms
Emission intensity [Counts/s]
300 °C 0,8
Intensity [counts]
80000 80000
Intensity [norm.]
0,6
60000 60000
0,4
40000 40000
20000 20000 0,2
0 0
500 550 600 650 700 750 800 850 900 0,0
200 250 300 350 400 450 500 550 600 650 700 750 800 350 400 450 500 550 600 650 700 750 800
Wavelength [nm]
Wavelength [nm] Wavelength [nm]
Excitation energy Temperature Time delay
54 27.03.2019Plagiarism Protection
Application of inorganic luminescent pigments to
• Plastics • Lacquer
• Ceramics • Polyurethan
foam
• Yarn • Special woven
fabric
• Medical • Printings
Limit of application: Luminescence is not observable in metals, but possible
in ceramic or polymer type coatings onto metals
55 27.03.2019Plagiarism Protection Analytical access: Excitation sources a) Steady state spectroscopy • Solar light • Incandescent lamps (350 - 3000 nm) • Deuterium lamps (115 - 370 nm) • 450 W Xe discharge lamp (250 – 1100 nm) b) Time resolved spectroscopy • Flash lamps • LEDs • Laser diodes • Solid state laser 56 27.03.2019
Plagiarism Protection
Analytical access: Detection
Type Detection by Requirements Required marker Security
to user concentration level
1 Human eye lowSummary and Outlook Inorganic luminescent materials • Individual rare earth doped inorganic luminescent pigments generate the highest security level in direct product marking • Small hand held spectrometer with high resolution and sensitivity is needed to read out the security code on-side • Tempering the individual security pigments extremely difficult because of the secret manufacturing process • Based on security pigments the business for counterfeiter will be much more difficult! 58 27.03.2019
Summary and Outlook
Inorganic luminescent materials for LEDs
Mature luminescent materials developed to encounter
• high luminous efficacy cool-white > 200 lm/W
• warm-white > 100 lm/W
• high CRI 70 - 95
• superior lifetime L70 > 10000 h
• retrofit designs for TL, CFL, GLS, …
Efficient luminescent materials for LEDs
Oxides Oxynitrides Nitrides Fluorides
Silicates (Ca,Sr,Ba)2SiO4:Eu (Ca,Sr,Ba)Si2N2O2:Eu (Ca,Sr,Ba)2Si5N8:Eu K2SiF6:Mn
Aluminosilicates a,ß-SiAlON (Ca,Sr)AlSiN3:Eu
Aluminates (Y,Gd,Lu)3Al5O12 (Sr,Ca)LiAl3N4:Eu Na3AlF6:Mn
Gallates ZnGa2O4:Mn (Sr,Ba)Mg2Ga2N4:Eu
Germanates Mg8Ge2O11F2:Mn
Molybdates Tb2Mo3O12:Eu
Tantalates K2TaF7:Mn
59 27.03.2019Summary and Outlook
Increase of energy density drives search for further novel materials
Rare Earth Phosphors Garnets Crystals/Ceramics
105
High energy particles
x-rays (< 1 nm)
Host lattice
Excitation energy [eV]
EUV (1 – 100 nm) 103
VUV (100 – 200 nm)
UV-C (200 – 280 nm) 10
UV-B (280 – 320 nm)
Sensitiser
UV-A (320 – 400 nm) 5
VIS (400 – 700 nm)
NIR (700 – 1400 nm) 1
Activator
0.01 0.1 1 10 102 103 104 105 106
Power density [W/cm2]
60 27.03.2019Summary and Outlook
Development of light sources driven by material science Ceramics
Nitrides
(In,Ga)N
Material (Al,In,Ga)P
control Garnets
GaAs
Halogen cycle
Rare Earth
MgWO4 & Phosphors
Zn2SiO4:Mn
C, Os, W
1895 1905 1915 1925 1935 1945 1955 1965 1975 1985 1995 2005 2015
Year
61 27.03.2019Literature Books A.H. Kitai, Solid State Luminescence, Chapman & Hall, London (1993) G. Blasse, B.C. Grabmeier, Luminescent Materials, Springer Verlag Berlin Heidelberg (1994) J.R. Coaton, A.M. Marsden, Lamps and Lighting, Arnold, London (1997) D.R. Vij, Luminescence of Solids, Plenum Press, New York and London (1998) S. Shinoya, W.M. Yen, Phosphor Handbook, CRC Press (1999) A. Zukauskas, M.S. Shur, R. Caska, Introduction to Solid-State Lighting, John Wiley & Sons, Inc. (2002) E.F. Schubert, Light Emitting Diodes, Cambridge Univ. Press (2003) J. Garcia Sole, L.E. Bausa, D. Jaque, An Introduction to the Optical Spectroscopy of Solids, John Wiley & Sons, Inc. (2005) C.R. Ronda, Luminescence, Wiley-VCH (2008) T. Jüstel, S. Möller, H. Winkler, Luminescent Materials in Ullmann‟s Encyclopedia of Technical Chemistry (2012) Kozai, T.; Fujiwara, K.; Runkle, E.S., LED Lighting for Urban Agriculture, Springer (2016) 62 27.03.2019
Literature Publications T. Jüstel, H. Nikol, C.R. Ronda, New Developments in the Field of Luminescent Materials for Lighting and Displays, Angew. Chem. 110 (1998) 3250 T. Jüstel, H. Nikol, Optimization of Luminescent Materials for Plasma Display Panels, Adv. Materials 12 (2000) 527 M. Born, T. Jüstel, Elektrische Lichtquellen, Chemie in unserer Zeit 40 (2006) 294 H. Hummel, P.K. Bachmann, T. Jüstel, J. Merikhi, C.R. Ronda, V. Weiler, Near-Infrared Luminescent Nano Materials for In-Vivo Optical Imaging, J. Nanophotonics 2 (2008) 021920 M. Kubus, D. Enseling, T. Jüstel, H.-Jürgen Meyer, Synthesis and Luminescent Properties of Red-Emitting Phosphors: ZnSiF6·6H2O and ZnGeF6·6H2O Doped with Mn4+, J. Luminescence 137 (2013) 88 T. Jüstel, Anorganische Leuchtstoffe und LEDs, CHEManager 5 (2017) J. Chen, S. Loeb, J-H. Kim, LED Revolution: Fundamentals and Prospects for UV Disinfection Applications, Envir. Sci.: Water Res. Technol. 3 (2017) 188 Internet-Links Homepage T. Jüstel (PISA & LISA) www.fh-muenster.de/juestel Philips (Signify) http://www.lighting.philips.de/home Tailorlux GmbH http://www.tailorlux.com 63 27.03.2019
Acknowledgement Research Group “Tailored Optical Materials“ for synthesis, photographs, spectroscopy, etc. HMS Boston, MA, USA, Dr. M. Purschke for fruitful discussions University of Tübingen, Germany Prof. H.-J. Meyer for fruitful discussions Vilnius University, Lithuania Prof. A. Kareiva for exchange of students Universiteit Utrecht, The Netherlands Prof. A. Meijerink for fruitful discussions FEE Idar-Oberstein and FGK Höhr-Grenzhausen for ceramics and crystals BMBF, BMWI, Merck KGaA Darmstadt, Philips Lighting Eindhoven, Merz Frankfurt, and DPL Emmerthal for generous financial support 64 27.03.2019
You can also read
