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Introduction to BAYTRON®
PEDOT Inherently Conductive Polymers forClear Conductivity…
History of PEDOTPEDOT ChemistryPEDOT-based CoatingsSome Application ExamplesHigh conductivity PEDOT types
Fall AIMCAL Technical ConferenceOctober 16-19, 2005, Myrtle Beach, SC
N N NN
SSSSSS
S
OORR
S
OORR
S
OORR
S
OORR
S
OORR
S
OORR
S
S
S
S
S
S
OO OO OO
O O O O O O
Polymeric Organic Conductors
PolyacetyleneH. Shirakawa & MacDiarmid
Polyaniline (H+ doped!)A. Heeger
Polythiophene
Poly(3,4-dialkoxythiophene)Hoechst AG
Poly(3,4-ethylenedioxythiophene)PEDOTBayer AG, HC Starck
Conductivity Range of ICPs
Metal
Semiconductor
Insulator
106 S/cm
102 S/cm
10-9 S/cm
10-20 S/cm
CopperIronGraphiteBismuth
Indium
Gallium/ArsenicGermanium
Silicon
Glass
DiamondSulfurPolyethylenePolystyrene PVCTeflonQuartz
Elec
tric
al c
ondu
ctiv
ity
Conductivity of PEDOT :
10-5 to 103 S/cm
Inherently conductive or coated antistatic plastics for:photographic films and packaging materialsthe electronics industry (e.g. batteries and capacitors)
Early conductive polymers were assumed to be:InsolubleNot meltableNot easily processable
Development of PEDOT
Interest in Conducting Polymers in the 1980s
BAYTRON® M Monomer (EDOT, 3,4-ethylenedioxythiophene)
BAYTRON® C “Catalyst” (Oxidant), Iron(III) toluenesulfonatein various alcohols
BAYTRON® P* Aqueous dispersions of PEDOT:PSS Polymer(various grades)
PEDOT Products
OO
S
No branching in 3- or 4- position possibleLinear polymer structureStabilization of the positive charge in the polymer chain by electron-donating substituentsHigh transmission compared to polypyrrole and polyanilineHigh stability of conductivityProcessable aqueous dispersions accessibleSafe-handling
Chemistry of PEDOT/PSS Dispersions
SO3H SO3H SO3H SO3HSO3-SO3
-
( )m
( )n
O OO OO O
SS
SS
SS
O O O O O O
2 +
Polymer-complex PEDOT/PSS
Aqueous template polymerization of EDOT in the presence of PSSA produces PEDOT/PSS:
Dark blue dispersionSolids content about 1.3% [or higher]5-mer to 15-mer PEDOT segmentsHole doped, approx 1 hole per 3 monomer units
S
O O5n+2
Fe2(SO4)3
Na2S2O8Polystyrene-sulfonic acid
0.02 0.04 0.06 0.08 0.100
1
2
3
4Analytical Ultracentrifugation
Particle Diameter (µm)
Parti
cles
(%)
PEDOT:PSS Is a Dispersion of Polymer Particles
Polystyrene Sulfonic AcidPEDOT
Secondary- and tertiary structures:
gel-particle95 % water5 % polymer
PSS-chain with PEDOT-oligomers
Gel Particle Interactions in PEDOT/PSS:From Dispersion to Dried Film
gel-particle
95 % water5 % polymer
STM image (31 x 31 nm2) of a spin coated PEDOT/PSS thin film*.
Syn. Met. 135-136 (2003) 53-54, Touwslager et al. of Philips Research Laboratories, Eindhoven, The Netherlands. Images from RIM, Univ. of Nijmegen, The Netherlands, Prof. H. van Kempen.
0.02 0.04 0.06 0.08 0.100
1
2
3
4Analytical Ultracentrifugation
A B C
Particle Diameter (µm)
Par
ticle
s (%
)
PEDOT:PSS 1:6 Solution Particle
Median [nm] Resistivity
[kΩcm] A 58 1.96 B 32 6.52 C 25 12.6
Particle Size Impacts Level of Conductivity
0.0
4.0x103
8.0x103
1.2x104
1.6x104
2.0x104
PEDT:PSS 1:6
Res
istiv
ity [O
hmcm
]
Shear Stress
A
B C
Shear stress reduces the particle size and increases the resistively
Energy Barrier-Controlled Transport in Films
Conductivity (S/cm) Grade + 5%
DMSO+ 5%
NMP + 5% EG
A ~1 80 98 99 B ~0.3 65 32 53 C ~5-10 400 454 492
Reducing resistance between particles:
Range of Conductivity
In situPEDOT
10-6 S/cm 102 S/cm10-2 S/cm
PEDOT/PSS Formulations
PEDOT/PSS (neat)
PEDOT/PSS PLED Grades
• In most applications, surface conductivity can be achieved using very thin films (< 1 µm) of PEDOT-based conductive polymers
• The PEDT layer is usually preferentially applied by using the aqueous polymer dispersion PEDOT/PSS
• Careful control of coating formulation, application method, drying conditions, etc. are required to adjust final film properties
Increase Resistivity
Decrease Viscosity
Decraease Surface Tension
Increase Solid ContentC
ondu
ctiv
ity
Vis
cosi
ty
Sur
face
Ten
sion
Solid
Con
tentWill impact
Increased Shearing
Dilution
Concentration
Addition of Ethanol
Decrease ViscosityIncreased Shearing
Sta
bilit
y
pH Addition of Base?
To By
Formulation Guideline Matrix
0
2
4
6
8
10
12
14
16
18
20
20 30 40 50 60 70 80 90 100
% Baytron P
Surf
ace
resi
stan
ce in
MO
hm/S
quar
e
Adjusting Conductivity by Adjusting Composition With Non-Conductive Binders
Surface Resistivity of Baytron /Polyurethane-Dispersion
Increasing PU dispersion
Increasing PEDOT/PSS
1E+2
1E+3
1E+4
1E+5
1E+6
1E+7
1E+8
1E+9
0.00 0.25 0.50 0.75 1.00 1.25 1.50
Dry film thickness [µm]
R [O
hms/
sq] CPP 103D (high binder content)
CPP 105D (low binder content)
Adjusting Conductivity by Adjusting Thickness
Transparency of PEDOT-Coatings – Varies With Amount of PEDOT/PSS in Dry Film
Transmission Spectra of PEDT/PSS(Data for 200 nm measured directly, all other curves are calculated)
0102030405060708090
100
200 300 400 500 600 700 800 900 1000 1100 1200 1300 1400 1500 1600 1700 1800 1900 2000 2100 2200 2300 2400 2500
Wavelength [nm]
Tran
smis
sion
[%]
50 nm100 nm200 nm500 nm1000 nm
Layer Thickness :
Coatings on PET filmsReference: air
50
60
70
80
90
10030
0
350
400
450
500
550
600
650
700
750
800
Wavelength ( nm )
Tran
smis
sion
(%)
PET Film 175 µm
CPP 103 D 2x10E5 ohm/sq 18 µm
CPP 105 D 1x10E4 ohm/sq 18 µm
CPP 103 D 3x10E4 ohm/sq 36 µm
CPP 105 D 3x10E3 ohm/sq 36µm
Transparency of Formulations – Two Examples
PEDOT/PSS contains acidic groups of sulfonic acids:
Metal ions and amines may react with acidic groupsadjust the pHmay crosslink sulfonic acid groups
PEDOT/PSS contains watercan be diluted with water indefinitelycan be diluted to some extent withwater-miscible solventscannot be diluted with non water-miscible solvents
Compounds sensitive to acidic hydrolysismay be hydrolyzedmay react further
PEDOT/PSS can be RedOx activereduction with strong reducing agents (e.g. hydrazine)overoxidation with strong oxidizing agents (e.g. hydrogen peroxide or hypochlorite)
General Guidelines For Formulating PEDOT/PSS Dispersions
AlcoholsMethanolGlycolEthanolIsopropanolButanol
KetonesAcetoneMethylethylketone
lesspolar
More polar alcohols are more miscible with PEDOT/PSS dispersionsEthanol is compatible at ~ 1:1Excessive addition of alcohols leads to agglomeration
CH3 CH3
O OH OPossible side reaction of ketones:
Condensation reactionFormation of diacetone alcohols from acetoneVery slow reaction
PEDOT:PSS dispersions can be partly diluted with water miscible solvents
Formulation With Water-Miscible Solvents
Amidic solventsNMPDMFDMAC
DMSO
NCH3
CH3O
CH3
HydrolysisOH
O
CH3
NHCH3
CH3
+Possible side reaction:
Formation of dimethylamine and acetic acidReaction is slow (within months)Dimethylamine reacts with PSS
Polar compounds, especially…
Amidic solvents likeN-methylpyrrolidone (NMP)N,N-dimethylformamide (DMF)N,N-dimethylacetamide (DMAC)
Dimethylsulfoxide (DMSO)
And low volatile alcohols likeethylene glycol (EG)glycerinsorbitol
Partly re-dissolve PEDOT-groupsRearrange morphologyDecrease resistance between PEDOT/PSS gel particlesIncrease film conductivity
During drying
Enhancing Conductivity With Additives
Multivalent cations or compounds with multiple basic groups can serve as crosslinkers for PEDOT:PSS :
PEDOT-segment
PSS-chain
Crosslinking by divalent metal ions isfast, with complete reaction in dispersionwill cause coagulation in the dispersionmay be used to enhance resistance towards solvent by subsequent treatment
MSO
O
S
OH
OO
S
OH
OO
SO
OO
*
S OO
O O
SOO
OM
Using Crosslinking Additives to Adjust Coating Properties
Silanes as crosslinking agents and hardening agents
TEOS(Tetraethylorthosilicate) Silicic acid
fast acid-catalyzed hydrolysisslower base-catalyzed condensation/network-formationmakes very hard coatingsespecially useful for coatings on glass
SiO
OO O
Et
Et
Et
EtHydrolysis
SiOH
OHOH OH
CondensationNetwork formation
SiO
OHOH OH
SiOH
OHO OHSi
OO
SiOH
O OH
SiO
OHOH
SiOH
OH
Using Crosslinking Additives to Adjust Coating Properties
Glycidyloxypropyltrimethoxy silaneSilquest® A 187™
hydrolysis like TEOSbut…additional reaction:
hydrolysis of the epoxy-groupreduced effectiveness over time if left in liquid formulation
SiO
OO
Me
Me
Me OO
SiOH
OHOH O
O
SiOH
OHOH O
O OHSOO
R
SiOH
OHOH O
OH OH
SOO
R
OH
H2O
Using Crosslinking Additives to Adjust Coating Properties
drying temperature between 80 to 200 °C.
drying time depends on coating thickness, temperature and air humidity and should be determined by appropriate application tests
minimum drying time is limited to about 30 to 60 s under practical conditions (due to the low evaporation rate of water from the polymer gel)
Drying temperature in °C
80 100 120 140 160 180 200
30
60
90
Dry
ing
ti me
in s
Recommended drying
Drying of PEDOT/PSS-Based Coatings
1.0E+03
1.0E+04
1.0E+05
1.0E+06
1.0E+07
1.0E+08
0 500 1000 1500Time in h
Con
duct
ivity
in S
/cm
CPP105D
CPP135D
CPP137D
CPP141D
2000
Stability/Aging of BAYTRON® CoatingsConditions: 52 ºC, 95% RH
Stability of PEDOT/PSS-Based Coatings
COMPONENT % BY WEIGHT BAYTRON® P (1.3% solids PEDOT/PSS dispersion)
57.65
Bayderm® Finish 85UD or Bayhydrol® 140 AQ (aqueous/solvent polyester-polyurethane binder solution)
15.63
N-Methyl-2-pyrrolidinone 3.48 Isopropanol 23.24 Total 100.00
Antistatic coating for thermoforming
Wet film thickness: 4 µm 6 µm 24 µmSurface resistivity: < 105 Ω/ 3.0 x 104 Ω/ 9.0 x 103 Ω/Quantity of BAYTRON® P used in coating: 2.3 g/m² 3.45 g/m² 13.8 g/m²
Coating Guide Formulation: Example CPP 4531II
outer graphite layer
PEDOTCOATING
deflection yoke
COMPONENT % BY WEIGHT BAYTRON® P (1.3% solids PEDOT/PSS dispersion) 32
Isopropanol 39 Ethylene glycol 16 Tetraethylorthosilicate 12 Acetic Acid 1 Total 100
Antistatic scratch-resistant coating for CRTs (glass)
Spray-applicationSurface resistivity: < 106 Ω/Pencil Hardness: 9HQuantity of BAYTRON® P used in coating: ~ 2 g/m²
Coating Guide Formulation: Example CPG 130.6
CPP141DCPP141D
Cond
uctiv
ity
CPP103DCPP103D
CPP105DCPP105D
CPP 116.6DCPP
116.6D
CPP 134.18DCPP
134.18D
CPP135DCPP135D
CPP4532ICPP4532I
S V2S V2
CPG 130.6CPG 130.6
CPUD2CPUD2
Polymer Coating – Antistatic or ESD
Glass coating
Polymer Coating - Thermoformable
Electrostatic coating
Polymer Coating – Conductive
Screen-printable coating paste
CPP4532E3D
CPP4532E3D
F HCF HC
F CPP105DMF CPP105DM
F PVAF PVA
100 Ω/sq
100 MΩ/sq
Hardness/Adhesion
PEDOT/PSS “Guide” Formulations – A Comparison
Flow Coating
Coater with NozzlesPipe with Formulation
AFTER
Coated Plastic Sheet
BEFORE
Uncoated Plastic Sheet
Tank with Coating Mixture
Roller Coating
Sheet to be coated
Transport Roll
Transport Belt
Supply Roll
Variable distance to control coating thickness
Common Coating Methods
film extrusionlongitudinal stretching
coating with ICPtransverse stretching
winding up
Conductive coating is applied in this step
Roll-to-Roll Coatings
PEDOT/PSS in Antistatic Coatings
LCD-Module Trays
Carrier TapesCover TapesPackaging films
Cathode Ray Tubes
LCD-Backlights
LCD-Polarizers
PEDOT/PSS in Conductive Applications
EL-Lamps1)
Touch-Screens
ITO-Replacement in LCD
1) Publication Bayer Material Science / Lumitec
PEDOT/PSS As an Electrode in Thick Film Electroluminescent Devices
Advantages of Using PEDOT/PSS:Replacement of ITOLower price compared to ITOElectrode patterned by screen printingSurface resistance ~ 500 to 5000 Ω /SimpleInexpensiveNo etching or patterningMoldable films possible
Operation Conditions:
U = 100 – 300 Volts AC
F = 100 – 400 Hz
Lumitec, Switzerland
0
1
10
100
1.000
10.000
1994 1997 1999 2002 2005 2008 2010Year
Con
duct
ivity
[S/c
m]
Baytron P
early versions PEDT:PSS
Baytron Pimproved versions
Baytron P high conductive versions
Indium Tin Oxide ?
Increasing the Conductivity of PEDOT:PSS
Challenge:
Transmission Spectra: ITO vs. PEDOT/PSS
400 600 800 1000 1200 1400 1600 1800 2000 22000
10
20
30
40
50
60
70
80
90
100
Transmission_ITO_AI4071.opj
ITO (d=120nm)
Baytron® P HC (d=255nm)in
tern
al T
rans
mis
sion
T/T
0
W avelength [nm]
Inte
rnal
Tra
nsm
issi
on (T
/T0)
x 1
00
10-2 10-1 100 101 102 103 104 105 1060
20
40
60
80
100
Transmission_ITO_Baytron P.opj
ITO σ = 5600 S/cm K = 2700 cm-1 (@550nm)
Baytron® P HC σ = 450 S/cm K = 10400 cm-1 (@550nm)
In-Situ_PEDT σ = 600 S/cm K = 21000 cm-1 (@550nm)
inte
rnal
Tra
nsm
issi
on T
/T0 [
%]
Surface Resistance Rsq [Ωsq]
V4
Absorption of PEDOT/PSS vs. ITO
Resistivity:
ρ = 1/σ [Ωcm]
Surface Resistance :ρ = Rsq · d
Item Unit PEDOT/PSS Formulation
ITO (Reference) Specification
Surface Resistivity Ω/sq 900 382 < 1000
Transmission (incl. Substrate)
% 88.2 88.6 > 88
Linearity % 0.6 0.6 -1.5 ~ +1.5
High temp. aging Times (SR rise) 1.8 1.8 < 2.0
High temp. and moisture aging
Times (SR rise) 1.2 0.9 < 2.0
Flex test Times 1.0 30.6 --
Pen-striking test Times 10,000,000 1,000,000 > 1,000,000
Character writing test
Times 200,000 100,000 --
Using PEDOT/PSS (Instead of ITO) in a Touch Panel Application
Comparison of Selected BAYTRON® P Types*
BAYTRON® Typical Applications Solids (%)
PEDOT:PSS ratio
Particle size, mean(nm)
Visc. (mPa-s)
Cond.(S/cm)
1 : 2.5 1
0.3
5 – 10
5 – 10
1
1 x 10-3
1 x 10-5
1 : 2.5
1 : 2.5
PH 500 Conductive coatingsEL-displays, TFTs, Touch screen electrodes
1.2 1 : 2.5 30 25 500
1 : 2.5
Antistatic coatingsESD protection coatings, such as for packaging, carrier tapes, LCD backlights and polarizersElectrochromicsElectrostatic coating primersElectronics packagingTransparent clean-room coatings
1 : 6
1 : 20
80
30
100
80
75
35
Ultra-thin antistatic coatings (CRTs), Optical coatings
80
20
80
>200
8
Conductive coatingsEL-displays, TFTs, Touch screen electrodes
Higher solids raw material for printing pastes
HIL for OLEDs and PLEDs, active matrix devices
15HIL for OLEDs and PLEDs, passive matrix devices
Cond.With 5% added DMSO(S/cm)
P 1.3 80
PH 1.3 65
P HC V4 1.2 400
P HS 4 -
P VP AI 4083
1.5 -
P VP CH 8000
2.8 -
* All values are approximate!
Ready-to-Use BAYTRON® Coating FormulationsProduct Applications Approximate
Surface Resistivity, Ω/(for 18-μm wet film thickness)
Approximate Transmission at ~ 500 nm, %(incl. 100-μm PET substrate)
~ 83%
BAYTRON® F E Conductive coatings ~ 300 ~ 85%
~ 87%
~ 84%
~ 88%
~ 78%
BAYTRON® F HC
Variable, but usually > 89%
~ 500Conductive coatings
Conductive coatings
Thermoformable antistatic coatings
General, all-purpose antistatic coating
BAYTRON® S V2 Screen-printable paste for circuitry in EL-displays and other applications
Approx. 1 kΩ/sq(14.5 g/m2 test print)
Coating formulations customized for specific applications – See Coating Guide for more details.
BAYTRON® F CPP 105DM
~ 2000
BAYTRON® F PVA ~ 3000*(prior to thermoforming)
BAYTRON® CPUD2 1 x 106
OTHERS…CPP 105D, CPP 134.18D, CPP 135D, etc.
Variable
Thank you for your attention !
Klaus Wussow Application Technology - BaytronFriedrich Jonas Application Technology - BaytronAndreas Elschner Development - Organic LEDsUdo Guntermann Coatings developmentUrsula Tracht Kinetic studiesAlexander Karbach X-Ray, AFM, TEM labKnud Reuter SynthesisUdo Merker Development Capacitor TechnologyWilfried Lövenich Application Technology - Baytron/Pilot plantStephan Kirchmeyer Manager of R&DKlaus Lerch Global Sales Manager – EOIIIRon Lubianez NAFTA Sales Manager – EOII & EOIII
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