Overview poe-2004

Printed Plastic Electronics

Effects of printing on conjugated polymer’s

conduction mechanisms

IFN - CNR

January, 27th 2004

Alessandro Manuelli

© Manuelli 2005

2/52

Printed Conjugated Polymers

OverviewBrief introduction to transistors and their characteristics

How a transistor works Remarkable output characteristics

Integrated plastic circuits (IPCs) Printing techniques

Requirements for a printing process Processes considered Continuous printing process

Suitable materials Theories about conduction Interesting polymers Importance of the morphology

Effects of printing and coating on conducting mechanisms Impedance spectroscopy Thermal induced transitions in PANI Printed PANI Coated and printed semiconductors

Applications Outlook

© Manuelli 2005

3/52


How an Organic Transistor WorksTransistors

IPCs

Printing

Materials

Results

Applications

Outlook

© PolyIC 2004

S D

G

NNN N

H H

H H

[ ]no+o+

o- o-AA

Polyaniline (PAni)

Electrodesconducting polymer

or metal

OH

( )n

Polyhydroxystyrene (PHS)

Insulatorinsulating polymer

n)(

S

R

S

R

S

R

S

R

Poly-3-alkylthiophene (P3AT)

Semiconductorconjugated polymer

COCH2CH2OC

O O

n)(

Polyester

Substrateflexible film

VGS

VDS

Channel due to electric field

© Manuelli 2005

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OFET - Output Characteristics

© PolyIC 2004

Saturation

Important parameters

Contact resistance

Mobility

Leakage currents

ON/OFF ratio

A fast way for testing circuits orwhich parameter tells what ?

Transistors

IPCs

Printing

Materials

Results

Applications

Outlook

© Manuelli 2005

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Spin coating

2. SemiconductorP3AT

Spin coating

3. Insulator

Lithography

4. Gate-electrode: Gold

:

Lithography

1. S/D-electrodesGold

Cleanroom class 100 Spincoating P3AT

*J. Ficker et al., Proc. of SPIE, 4466 (2001), 95-102 A. Ullmann et al., Mat. Res. Soc. Symp. Proc., 665 (2001), C7.5.1

Development with Photo Lithography Rapid prototyping process

© PolyIC 2004

Transistors

IPCs

Printing

Materials

Results

Applications

Outlook

© Manuelli 2005

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SPIE 2003 San Diego

GND

-

• 192 kHz (at -60V)• stage delay 370 ns

• L = 2.6 µm• 15 OFETs (7 stages), 10 Vias

Layout:

Results:

f ~ µ * U / L²

© PolyIC 2004

Results with Photo lithographyRing oscillators

Transistors

IPCs

Printing

Materials

Results

Applications

Outlook

© Manuelli 2005

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Comparison of frequency of organic based integrated circuits:

Improvement from 2001 to 2002© PolyIC 2004

TechnologyComparison of ring oscillator performances

Infineon 4,7 kHz 20023,5 kHz 2001

PhilipsPhilips 2 kHz 2001

60 Hz 2001

PolyIC200 kHz 2002

106 kHz 2001

600 kHz 2004

Transistors

IPCs

Printing

Materials

Results

Applications

Outlook

© Manuelli 2005

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conventional digital

relief planar gravure screen ink jet electrogr. thermalmagnetho.

• letterpress

• flexoprinting

• offset • pad printing • continuous

• drop-on- demand

• xerography similiar to • transfer

• sublimation

printing techniques

“the world of printing meets the world of electronics”

© PolyIC 2004

Printing of Polymer ChipsDemand for high quality printing processes

Transistors

IPCs

Printing

Materials

Results

Applications

Outlook

© Manuelli 2005

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< 1 µm

Printing of Polymer ChipsLayer configuration and dimensionsof Organic Field Effect Transistor

10 µm

Drain

Source

ca. 100 µm

Gate

“More accuracy required for printing techniques”

© PolyIC 2004

Transistors

IPCs

Printing

Materials

Results

Applications

Outlook

© Manuelli 2005

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Lab printing with standard printing methods:• first attempts towards printed electronics

Gravure offset printing:high resolution electrodes

Screen printing:homogeneous films

Printing proofer:gravure printing

flexo printing

coating:homogeneous films

© PolyIC 2004

Development of Printing TechniquesLab. printing and coating techniques

Transistors

IPCs

Printing

Materials

Results

Applications

Outlook

© Manuelli 2005

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cliché

pad

doctor blade

ink

20 µm resolution

Pad printing Printed Source / Drain structures

1)

2)

Sour

ce Drain

© PolyIC 2004

Development of Printing TechniquesLab. Printing: pad printing for high resolution

Transistors

IPCs

Printing

Materials

Results

Applications

Outlook

© Manuelli 2005

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Blade with a fixed slit and moved by an engine with a constant speed

Substrate

Semiconductor

Doctor blade Insulator

Substrate

Doctor blade

Development of Printing Techniques Lab printing: doctor blade for homogeneous coating

© PolyIC 2004

Transistors

IPCs

Printing

Materials

Results

Applications

Outlook

© Manuelli 2005

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Development of Printing Techniques Lab printing: flexography for a continuous process

“A good potential in term of resolutions and speed”

Ink bath

Anilox cylinder Doctor blade

Printing cylinder with flexible stereo

Web

© PolyIC 2004

Transistors

IPCs

Printing

Materials

Results

Applications

Outlook

© Manuelli 2005

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Development of Printing TechniquesThe research machine for testing continuous processes

Under construction

Finished with its enclosure and air filtration

© PolyIC 2004

Transistors

IPCs

Printing

Materials

Results

Applications

Outlook

© Manuelli 2005

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Electrodes: Polyaniline (PANI) and Poly(3,4-ethylenedioxythiophene) (PEDOT)

NNN N

H H

H H

[ ]no+o+

o- o-AA

Doped Polyaniline (PANI)

Poly(styrene sulfonic acid)

Poly(3,4-ethylenedioxythiophene)

Baytron P*

*L. B. Groenendaal et alt., Adv. Mater., 12, n.7 (481-493), 2000

Transistors

IPCs

Printing

Materials

Results

Applications

Outlook

© Manuelli 2005

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Semiconductors Based on Polythiophenes

n)(

S

R

S

R

S

R

S

R Poly-3-alkylthiophene regioregular, commercial

*M. C. Magnoni et alt., Acta Polymer. 47, (228-233), 1996

Poly(3,3”-dihexyl-2,2’:5’,2”-terthiophene)*

Transistors

IPCs

Printing

Materials

Results

Applications

Outlook

© Manuelli 2005

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Structure of Semiconducting Polymers

Space-filling models of P3OT chains

Stick model of one P3OT chain

Poly(3-octylthiophene) (P3OT)

n)(

S

R

S

R

S

R

S

R

© PolyIC 2004

Transistors

IPCs

Printing

Materials

Results

Applications

Outlook

© Manuelli 2005

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Theory of Band Conduction*

*D. O. Cowan et alt., C&EN special report, July 21

(28-45),1986

Eg

Eg Empty levels

Filled levels

Insulator Semiconductor Metal

Schematic representation of the allowed energy states for an insulator, semiconductor, and metal. The boxes indicate the allowed energy regions. Coloured areas represent regions filled with electrons. Regions between the boxes represent forbidden energy levels and Eg is the energy gap between filled and empty states.

Transistors

IPCs

Printing

Materials

Results

Applications

Outlook

© Manuelli 2005

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Bipolarons in Polymers

Dication (bipolaron, bound, no spin)

Radical cation(polaron, spin)

SS

SS

SS

SS

-e-

SS

SS

SS

SS

-e-

SS

SS

SS

SS

Polythiophene

QB B

Formation of polaron during the oxidation process of a polythiophene.

Conduction bands

Valence bands

Neutral polymer has full valence and empty conduction bands

Removal of one electron forms polarons

Removal of second electron forms bipolaron

Removal of more electrons forms bipolaron bands

Increased doping produces bipolarons bands and removes states from both the valence and conduction band.

Transistors

IPCs

Printing

Materials

Results

Applications

Outlook

© Manuelli 2006

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Band conduction

X

Conduction allowed only in empty bands

Ef Ef EfEf

V V

Electrode Electrode Electrode

Transistors

IPCs

Printing

Materials

Results

Applications

Outlook

© Manuelli 2005

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Materials for Polymer ElectronicsOrganic Conductors and Semiconductors

Nobel Prize in 2000 for the discovery of organic conductors

regioregular Poly(3-hexylthiophen)solution processable

Pentacenhigh values for vacuum deposition

10-5 10-4 10-3 10-2 10-1 1 10µ [ cm2/Vs ]

-

Si

S/cm ]10 510 410 310 210 110 010-1 10 6

Comp.: Copper

Polyacetylene

Polyaniline

PEDOT

b) Charge carrier mobility (µ) of special organic semiconductors

a) Conductivity () of special organic conductors

n)(

S

R

S

R

S

R

S

R

regioregular Poly(3-hexylthiophen)solution processable

Pentacenhigh values for vacuum deposition

10-5 10-4 10-3 10-2 10-1 1 10µ [ cm2/Vs ]

-

Si

S/cm ]10 510 410 310 210 110 010-1 10 6

Comp.: Copper

Polyacetylene

Polyaniline

PEDOT

b) Charge carrier mobility (µ) of special organic semiconductors

a) Conductivity () of special organic conductors

n)(

S

R

S

R

S

R

S

R

PentaceneHigh values for vacuum deposition

Regioregular poly(3-hexylthiophene)Solution processable

© PolyIC 2004

Transistors

IPCs

Printing

Materials

Results

Applications

Outlook

© Manuelli 2005

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Regioregularity, Orientation and Alignment

Sirringhaus et alt., Nature 401, 685 (1999) Charge flow

SS

SS

SS

SS

Low regioregularity High regioregularity

Charge flow

S S

S S

SS

SS

10-1

10-4

70 98%HT

© PolyIC 2004

Transistors

IPCs

Printing

Materials

Results

Applications

Outlook

© Manuelli 2005

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Supramolecular Order of Functional Polymers*

*R. D. McCullough et alt., Handbook of Conducting Polymers, Second Edition

Transistors

IPCs

Printing

Materials

Results

Applications

Outlook

© Manuelli 2005

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Polycrystallinity in PolymersTransistors

IPCs

Printing

Materials

Results

Applications

Outlook

© Manuelli 2005

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Impedance Spectroscopy

Input:V = Vm·eit

Output:I = Im·eit’

Y() = Im·eit’/ Vm·eit = (Im/Vm) · eit’-it = Ym · ei Ym= admittance = t

Z() = 1/Y = (1/Ym) · e-i = Z’ - i Z’’

Z’ = Zm cos()Z’’ = Zm sen()

Transistors

IPCs

Printing

Materials

Results

Applications

Outlook

© Manuelli 2005

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Impedance SpectroscopyEquivalent circuits

Transistors

IPCs

Printing

Materials

Results

Applications

Outlook

© Manuelli 2005

27/52


Impedance SpectroscopyPlot

Recorded plot

Equivalent circuit

Transistors

IPCs

Printing

Materials

Results

Applications

Outlook

© Manuelli 2005

28/52


Conducting PolymersNon ohmic conductivity in coated PANI

A

l

L1 R1 R2

C1

R3

CPE1

R4

C3

W1

Element Freedom Value Error Error %L1 Free(±) 6,5029E-6 N/A N/AR1 Free(±) -1571 N/A N/AR2 Free(+) 2923 N/A N/AC1 Free(+) 9,7092E-13 N/A N/AR3 Free(+) 27,63 N/A N/ACPE1-T Free(+) 3,8108E-16 N/A N/ACPE1-P Free(+) 1,726 N/A N/AR4 Free(+) 769,2 N/A N/AC3 Free(+) 3,1075E-11 N/A N/AW1-R Free(+) 64,72 N/A N/AW1-T Free(+) 3,645E-8 N/A N/AW1-P Free(+) 0,69234 N/A N/A

Data File:Circuit Model File: C:\Documents and Settings\Sasso\Documenti\PhD\IS-data-04-07-23\Pani\Amf294\Dry\04-02-23\L-R-P1-PCPE-P2-Ws.mdlMode: Run Fitting / Selected Points (0 - 0)Maximum Iterations: 1000Optimization Iterations: 100Type of Fitting: ComplexType of Weighting: Calc-Modulus

= 14 S/cm

r. h. 0%

500 1000 1500 2000 2500

-1500

-1000

-500

0

500

Z'

Z''

102 103 104 105 106 107 108102

103

104

Frequency (Hz)Z'

-750

-500

-250

0

250

Z''

Transistors

IPCs

Printing

Materials

Results

Applications

Outlook

© Manuelli 2005

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Conducting Polymers Influence of relative humidity on conductivity

0 1000 2000 3000 4000

-4000

-3000

-2000

-1000

0

Z'

Z''

Time

= 14 S/cm at r. h. 0%

= 17.3 S/cm at r. h. 32%

Conductivity increases

Constant dedoping at r. h. 72%

Conductivity decreases

500 1000 1500 2000 2500

-1500

-1000

-500

0

500

Z'

Z'' Dry

32%

Transistors

IPCs

Printing

Materials

Results

Applications

Outlook

© Manuelli 2005

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Conducting Polymers Thermal analysis of PANI: TGA, DSC

1st run

Recrystall.

2nd run

TGA shows a stability of PANI over 200° C

DSC shows an irreversible transition at 160° C

Transistors

IPCs

Printing

Materials

Results

Applications

Outlook

© Manuelli 2005

31/52


Conducting Polymers UV-Vis analysis of PANI

The thermal transition affects the orbitals’ energy

Transistors

IPCs

Printing

Materials

Results

Applications

Outlook

© Manuelli 2005

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Conducting Polymers Simpler conducting mechanism

L1 R1 R2

CPE1

W1

Element Freedom Value Error Error %L1 Free(±) 2,5636E-6 N/A N/AR1 Free(±) 98,23 N/A N/AR2 Free(+) 479,3 N/A N/ACPE1-T Free(+) 3,2343E-12 N/A N/ACPE1-P Free(+) 1,058 N/A N/AW1-R Free(+) 126,6 N/A N/AW1-T Free(+) 5,0218E-8 N/A N/AW1-P Free(+) 0,48469 N/A N/A

Data File:Circuit Model File: C:\Documents and Settings\Sasso\Documenti\PhD\IS-data-04-07-23\Pani\AMF303\CaCl2\04-05-17\L-R-RCPE-Ws.mdlMode: Run Fitting / Selected Points (0 - 0)Maximum Iterations: 1000Optimization Iterations: 100Type of Fitting: ComplexType of Weighting: Calc-Modulus

550 600 650 700 750

-150

-100

-50

0

50

Z'

Z''

102 103 104 105 106 107 108

-30

-20

-10

0

10

20

Frequency (Hz)Z'

'

= 45 S/cm at r. h. 32%

Transistors

IPCs

Printing

Materials

Results

Applications

Outlook

© Manuelli 2005

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Conducting Polymers Rinsing treatment

300 400 500 600 700 800 900

-500

-400

-300

-200

-100

0

100

Z'

Z''

Time

Doping acid surfaces and affects the conductivity

A rinsing step solves the problem

Transistors

IPCs

Printing

Materials

Results

Applications

Outlook

© Manuelli 2005

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Conducting Polymers Ohmic conductivity in PANI

300 400 500 600 700

-300

-200

-100

0

100

Z'

Z''

r.h. 32%

r.h. 72%

582,5 585,0 587,5 590,0 592,5

-7,5

-5,0

-2,5

0

2,5

Z'

Z''

102 103 104 105 106 107 108

-25

0

25

50

75

100

Frequency (Hz)Z'

'

r.h. 32%

r.h. 72%

= 48.5 S/cm at r. h. 32%

= 50.0 S/cm at r. h. 72%

Devices: Knobloch A. et alt., Journal of Applied Physics 96, 2286 (2004)

Transistors

IPCs

Printing

Materials

Results

Applications

Outlook

© Manuelli 2005

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Conducting PolymersInfluence of the rinsing solvent and technique

dry32%72%

98%

500 750 1000 1250 1500 1750

-1000

-750

-500

-250

0

250

Z'Z'

'Annealing and rinsing with acetone = 7 S/cm at r. h. 0%

= 10 S/cm at r. h. 32%

= 16 S/cm at r. h. 72%

= 21 S/cm at r. h. 98%

Spin coating, annealing, rinsing with ethanol

= 20 S/cm at r. h. 32%

Transistors

IPCs

Printing

Materials

Results

Applications

Outlook

© Manuelli 2005

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Conducting Polymers Transistor with flexo printed D/S

S/D: PANI 5% w/w in Toluene = 49 S/cm

Semiconductor: P3HT in chloroform, spin coated

Insulator: PMMA in dioxane, spin coated

Gate: Au sputtered

ON/OFF ratio = 4

Uth = +30 V

= 4.5 x 10-4 cm2/Vs

Transistors

IPCs

Printing

Materials

Results

Applications

Outlook

© Manuelli 2005

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Semiconducting Polymers Spin coating v.s. doctor blade

Transistor with two doctored layers

Traditional spin coated transistor

Sour

ce

Drain

Gate

D/S: Au, photolithography

Semiconductor: P3HT doctored

Insulator: polymer blend, doctored

Gate: Au, photolithography

D/S: Au, photolithography

Semiconductor: P3HT, spin coating

Insulator: polymer blend, spin coating

Gate: Au, photolithography

Manuelli A. et alt., Proceedings of Polytronic 2002, 201 (2002)

Transistors

IPCs

Printing

Materials

Results

Applications

Outlook

© Manuelli 2005

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Semiconducting Polymers Transistors’ output characteristics

Doctored

ON/OFF ratio = 12

Uth = +4 V

= 2.7 x 10-2 cm2/Vs

Spin-coated

ON/OFF ratio = 10

Uth = +8.5 V

= 2 x 10-2 cm2/Vs

Transistors

IPCs

Printing

Materials

Results

Applications

Outlook

© Manuelli 2005

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Semiconducting PolymersFlexo printed structures

PDHTT 0.5% w/w in chloroform flexo-printed. (a) (b) and (c) three different kinds of structures; (d) particular of two fingerprints.

(a) (b)

(c) (d)

Transistors

IPCs

Printing

Materials

Results

Applications

Outlook

© Manuelli 2005

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Semiconducting PolymersAFM

1 m 5 m 10 m

1 m 5 m 10 m

P3HT flexo printed

P3HT spin coated

Transistors

IPCs

Printing

Materials

Results

Applications

Outlook

© Manuelli 2005

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Printed Electronics – Application fieldstwo main fields

RFID tagsRadio Frequency IDentification- ePC*- identification- brand protection- anti theft- logistics

Printed ElectronicDevices- single devices- display circuits- games / give aways

*ePC:Electronic Product Code

© PolyIC 2004

Transistors

IPCs

Printing

Materials

Results

Applications

Outlook

© Manuelli 2005

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Applications of Polymer Chipsdriving circuits for displays

Plastic matrix displays

Flexible displays• OLED, LCD, electrochrome, others • display on „any“ electronics, ...

Properties:• thin• flexible • inexpensive • large areas possible• rapid prototyping of electronics

• single use possible• disposable possible

© PolyIC 2004

Transistors

IPCs

Printing

Materials

Results

Applications

Outlook

© Manuelli 2005

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Applications of Polymer Chips marketing products, games, give aways

Toys

Give aways

Use for: • marketing, • single use electronics • games• give aways• ...



© PolyIC 2004

Transistors

IPCs

Printing

Materials

Results

Applications

Outlook

© Manuelli 2005

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Application of Polymer ChipsSensors



Sensors

Use for: inexpensive sensors, single use sensors,large area sensor matrices, ....

© PolyIC 2004

Transistors

IPCs

Printing

Materials

Results

Applications

Outlook

© Manuelli 2005

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Application of Polymer ChipsPolymer chip RFID-tags

© PolyIC 2004

Sender / reader(conventional)

Transponder -RFID - Tag

send

er /

read

er Vcc

GND

OUT

rectifier

antenna

RF-waves

Transponder -chip

Standard - Tag: medium costmedium volume

IPC - Tag

low costhigh volume

• RFID: radio frequency identification

• contactless reading

Transistors

IPCs

Printing

Materials

Results

Applications

Outlook

© Manuelli 2005

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Application of Polymer Chips RFID-tagsMany areas

© PolyIC 2004

Identification

Automation

Electronic watermarkElectronic tickets

Logistics

Electronic bar code

Polymer RFID-Tags:• thin, flexible • inexpensive• onto „any“ product

Transistors

IPCs

Printing

Materials

Results

Applications

Outlook

© Manuelli 2005

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Application of Polymer Chips RFID-tagsThe electronic Product Code ePC

© PolyIC 2004

Electronic check-out

Electronic bar code

plastic transistor

Functional polymers

Transmitter / receiverreads information of electronic barcodes

Electronic payment andlogistics

Shopping trolley Sender / Receiver

„intelligent packages with electronic product codes“

Picture: new world

Transistors

IPCs

Printing

Materials

Results

Applications

Outlook

© Manuelli 2005

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Plastic Chips vs. Silicon Chips: Not a competition, but different fields

Number of transistors per chip (approx.)

Syst

em c

osts

, app

rox.

(€)

Plasticsfield

Siliconfield

1 10 103

10-1

10-2

10-3

102

1

101

102 104 105 106 107

Plastics

Silicon

low complexity, costs driven by:

process, packaging

actual

tendency

high complexity,costs driven by:

size, density, yield

approximate values

© PolyIC 2004

Transistors

IPCs

Printing

Materials

Results

Applications

Outlook

© Manuelli 2005

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Chip or Chipless RFID? - Polymer ChipRFIDs are the missing link towards ePC

performance

volume

cost

transmission of information

application on each good

Si - Chip Polymer - Chip chipless

prop

ertie

sap

plic

atio

ns

© PolyIC 2004

Transistors

IPCs

Printing

Materials

Results

Applications

Outlook

© Manuelli 2005

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The future of RFID:Lowest price - highest volume

Trillions

Tens of Billions

Billions

Hundredsof Millions

Millions

Tens ofThousands

Thousands

2c

10c

30c

$1

$10

$100

Up to 1c

ActiveChip

PassiveChip

PolymerCircuits

OtherChipless

Source: IDTechEx Limited, Issue 12

© PolyIC 2004

Transistors

IPCs

Printing

Materials

Results

Applications

Outlook

© Manuelli 2005

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IPCs are a new platform technology forlow cost, high volume, simple applications

• RFID tags- electronic product code (ePC)

• printed electronic devices• single use electronics• active displays • sensors

“low cost electronics for new mass markets - not a substitute for standard electronics”

Printed Integrated Polymer Circuits - IPC

© PolyIC 2004

Transistors

IPCs

Printing

Materials

Results

Applications

Outlook

© Manuelli 2005

52/52


A “New Electronics Revolution“ with printed electronics

Vacuum tube triode1906

Transistor1947

Radio in every house

Computer, etc.on every desk

printed electronicseverywhere

PrintedTransistor

2001

© PolyIC 2004

Transistors

IPCs

Printing

Materials

Results

Applications

Outlook

Potential of Integrated Polymer Circuits - IPC

Education

Overview poe-2004