D.S.H. Charrier Dimitri S.H. Charrier
Jan 18, 2016
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