D.S.H. Charrier

Dimitri S.H. Charrier

D.S.H. Charrier

1 Long term project.•SKPM potentiometry.•STM potentiometry.•A detour…

PEDOT:PSS.•Giant actuation.•Memory.

Process partially explained…•Drying effect.•Sorbitol.

2

3

} on high performance organics

D.S.H. Charrier

1 Long term project.•SKPM potentiometry.•STM potentiometry.•A detour...

PEDOT:PSS.•Giant actuation.•Memory.

Process partially explained…•Drying effect.•Sorbitol.

2

3

D.S.H. Charrier

2 4 6 8 10 12 14

0

2

4

6

8

10

X (m)

surf

ace

po

ten

tial (

V)

0

10

20

30

40

he

igh

t (nm

)

patterned in clean room

simulated with COMSOL and MatLab

dielectric

source

gate

tip

drain

active layer

lever

Our results on test devices

L. Bürgi et al, Synthetic Metals, 146, 297 (2004)

P3HTT = 165 K

D. Charrier et al, submitted

D.S.H. Charrier

electronic control

UHVchamber

STM head

Home built

D.S.H. Charrier

before field after field

Typical polymer used for organic actuation, polypyrrole = PPy.Largest Strain (elongation) = 36.7 %Redox reactions involveld, PPy↔PPy+.Anionic counter ions to maintain charge neutrality.

A huge height increase = 230 nm

PEDOT:PSS as active layer(thickness: 60-70 nm)

S. Hara et al, Synthetic Metals, 156, 351 (2006)

PEDOT

PSS

D.S.H. Charrier

1 Long term project.•SKPM potentiometry.•STM potentiometry.•A detour...

PEDOT:PSS.•Giant actuation.•Memory.

Process partially explained…•Drying effect.•Sorbitol.

2

3

D.S.H. Charrier

-5 0 5 10 15 20 25 30 35 40

0

50

100

150

200

250

300

heig

ht (

nm)

x (m)

-5 0 5 10 15 20 25 30 35 40

0

50

100

150

200

250

300

heig

ht (

nm)

x (m)

SiO2

AuAu

saturation

+-

Before field (pristine) After field

Initial thickness of PEDOT:PSS = 60-80 nmSpin-coated on glass or on SiO2

A height increase of about 400% !!!

D.S.H. Charrier

0 20 40 60 80 100 1200

50

100

150

200

250

+3.7V,0V,-3.7V

1.finger 2.finger

t (min)

ave

rag

ed

he

igh

t (n

m)

-3

-2

-1

0

1

2I (

A)

Saturation (non reversible)

+ 3.7 0 - 3.7 V

Reversible…

D.S.H. Charrier

-2 0 2 4 6 8 10 12 14 16 18 20 22

20

30

40

50

t (min)

aver

aged

hei

ght (

nm)

Reversible cycles > 12

Switching the bias +/- 4 V

Reversible height increase of about 50%

0 1 2

20

30

40

50

t (min)aver

aged

hei

ght (

nm)

+4 0 -4 0

zoom

D.S.H. Charrier

U (V) t (s) U (V) t (s) U (V) t (s) U (V) t (s) I off (A) I on (A)1 4 30 0.5 10 -4 30 0.5 10 2.93E-08 2.45E-08 8.35E-012 4 60 0.5 10 -4 60 0.5 10 3.86E-09 1.60E-08 4.14E+003 3.5 30 0.5 10 -3.5 3 0.5 10 1.22E-09 3.65E-09 3.01E+004 4 30 0.5 10 -4 4 0.5 10 2.69E-09 6.60E-09 2.46E+005 3.5 60 0.5 10 -3.5 10 0.5 10 5.38E-10 6.07E-09 1.13E+016 3.5 90 0.5 10 -3.5 20 0.5 10 1.51E-11 7.06E-09 4.66E+027 4 30 0.5 10 -4 30 0.5 10 3.87E-10 8.77E-09 2.26E+018 4 3 0.5 1 -4 3 0.5 1 -3.27E-09 1.64E-08 -5.00E+009 4 3 0.1 0.4 -4 3 0.1 0,4 -2.27E-08 2.54E-08 -1.12E+00

readwrite On/OffOn/Off ratioreaderase

Best ratio we gotOn/Off = 466

Optimal organic memoryOn/Off > 10 000

0 20 40 60 80 100

-500

-400

-300

-200

-100

0

100

200

300RER

I (nA

)

t (s)

W

On/Off ratio

Hint: electrochemical alteration?

0 1 2 3 4-0.50.00.51.01.52.02.53.03.54.0

curr

en

t (A

)

voltage (V)

1 2 3 4beginning

finishing

+ 4 0.5 -4 0.5 V

D.S.H. Charrier

1 Long term project.•SKPM potentiometry.•STM potentiometry.•A detour...

PEDOT:PSS.•Giant actuation.•Memory.

Process partially explained…•Drying effect.•Sorbitol.

2

3

D.S.H. Charrier

PEDOT:PSS is hygroscopic…

•At 40-60 % of H20 in air, motion for > 3.5 V•At 20 % motion for > 50 V•At 13 % no motion visible

‘dry’

‘wet’

2 remarks:•2 bumps at around +/-2 V•Indication for ionic current

-10 -8 -6 -4 -2 0 2 4 6 8 10-800.0

-600.0

-400.0

-200.0

0.0

200.0

400.0

600.0

800.0

curr

ent (A

)

voltage (V)

‘wet’

‘dry’

D.S.H. Charrier

0 10 20 30 40 50 60-40

-20

0

20

40

60

80

100

120

heig

ht (

nm)

position (m)

0 10 20 30 40 50-40

-20

0

20

40

60

80

100

120

heig

ht (

nm)

position (m)

before after

thickness = 90-100 nm

+- -

sorbitol+anneal: more compact morphology.

(sub)conclusion:

Other actuation mechanism-5 0 5 10 15 20 25 30 35 40

0

50

100

150

200

250

300

he

igh

t (n

m)

x (m)

+-

no sorbitol

D.S.H. Charrier

At positive electrode 2 reactions may occur:

PEDOT + PSS- → PEDOT+(PSS-) + e- (1)

•Charge neutrality requires movement of PSS- to + electrode.•Large volume increase at + electrode•Requires mobile PSS (‘large size’)…

PEDOT(PSS Na) → PEDOT+(PSS-) + Na+ + e- (2)

•Charge neutrality requires movement of Na+ away from + electrode.•Smaller volume change, sign can be + or -•Requires mobile Na (‘small size’)

Adapted from: Elisabeth Smela, Adv. Mater. 2003, 15, 481. (Review)

‘Wet’

‘Dry’‘Sorbitol’

D.S.H. Charrier

all images: 500 500 nm2, z = 20 nm, done by Alex Nardes

anneal at 200C

kBT ~ 40 meV

F Lchar = (4 V/4m) 40 nm ~ 40 meV

(voltage/channel length ~particle size)

Can the field move any material?

D.S.H. Charrier

Color changing ?

Before field After/during field

+-

Electrochromic devices

Electrochemical reaction at + electrodeor

PEDOT+ moving to anode…?

‘bluish’

Sorbitol case‘brownish’

D.S.H. Charrier

Reaction ?

www.baytron.com

PEDOT to + ?

?

D.S.H. Charrier

•Prediction of SKPM response via 3D modeling•STM as alternative to SKPM: in progress

•Giant actuation based on PEDOT:PSS•Organic memory based on PEDOT:PSS encouraging

•Actuation partially explained by ionic current and mass transport•Activation energy explains the motion•Optical changes visible

PEDOT + PSS- → PEDOT+(PSS-) + e-

PEDOT(PSS Na) → PEDOT+(PSS-) + Na+ + e-

D.S.H. Charrier

M2N / TU/e

Lukáš BřínekMartijn KemerinkAlex NardesRené JanssenGérard Wijers

OED / TU/e

Barry SmalbruggeTjibbe de Vries