Organic Thin-Film Transistors
with
enhanced sensing capabilities
L. Torsi, D. Angione, F. Marinelli and F. Palmisano
Dipartimento di Chimica - Università di Bari - (Italy)
[email protected]
SIF – XCIV Congresso Nazionale – Genova 23.09.08
Organic TFT sensors
analyte
organic semiconductor
source
⊕ ⊕ ⊕ ⊕ ⊕ ⊕ ⊕ ⊕ ⊕ ⊕ ⊕ ⊕ ⊕ ⊕ ⊕ ⊕ drain
dielectric
gate
conducting channel
Vg
Ids
Vds
A. Tsumura, H. Koezuka and T. Ando, Appl. Phys. Lett., 49, 1210, 1986 (1° OTFT)
H. Laurs and G. Heiland, Thin Solid Films 149 (1987) 129-142 (1° OTFT sensor)
A. Assadi, G. Gustafsson, M. Willander, C. Svensson, O. Inganas, Synth. Met. 37 (1990) 123
L. Torsi, A. Dodabalapur, L. Sabbatini, P.G. Zambonin,
Sensors and Actuators B., 67, 312, 2000.
SIF – XCIV Congresso Nazionale – Genova 23.09.08
OTFT pressure sensor: toward
artificial skin
Prof. T. Someya
University of Tokyo
T. Someya, T. Sekitani, S. Iba, Y. Kato, H. Kawaguki, T. Sakurai, PNAS, 101, 9966, 2004.
Ids (μA)
-80
Vg = - 100V
(a)
-60
Vg = - 80V
-40
Vg = - 60V
-20
Vg = - 40V
0
Vg = - 0V
0 -20 -40 -60 -80 -100
Vds(V)
square root - Ids (A)
DH-α6T OTFT
0,012
0,010
(b)
Vt= -1.72 V
2
μ= 0.095 cm /V s
0,008
0,006
0,004
0,002
0,000
20 0 -20 -40 -60 -80-100
Vg (V)
SIF – XCIV Congresso Nazionale – Genova 23.09.08
DH-α6T morphology
DHα-6T
90 nm
200 nm
400 nm
EB
Grain surface
500 nm
1
μ
=
1
μC
+
500 nm
500 nm
1
μGB
⎛ EB ⎞
μGB ∝ exp⎜ − ⎟
⎝ kT ⎠
100 nm
100 nm
100 nm
Organic Thin-Film Transistors with Enhanced Sensing Capabilities.
M. Daniela Angione, Francesco Marinelli, Antonio Dell’Aquila, Alessandro Luzio,
Bruno Pignataro and Luisa Torsi. Proceedings symposium e-MRS 2008 in press
SIF – XCIV Congresso Nazionale – Genova 23.09.08
Sensing measurements on OTFT
Tran-characterisics in
in
-60Tran-characterisics
NN2
2
-50
N
Butanol
-40
-30
-20
-10
0
-4
1x10
|Ids(A)|
ΔI
-6
10
-7
Trans-characteristics
10
Trans-characteristics
in
inbutanol
butanol
-8
10
(a)
(b)
20 0 -20 -40 -60 -80 -100
20 0 -20 -40 -60 -80 -100
Vg(V)
Vg(V)
DH-α6T / butanol
-50
-50
-40
(d)
Butanol
N2
-40
Ids (μA)
Ids (μA)
Ids(μA)
N2
Butanol
-5
1x10
2
-30
-20
-30
-20
-10
-10
(c)
0
0
0
-20
-40
-60
Vds (V)
-80
-100
0
-20
-40
-60
Vds (V)
-80 -100
SIF – XCIV Congresso Nazionale – Genova 23.09.08
Response repeatability
dDDα6T/1-hexanol, Vds = -5V
Ianalyte(μA)
-5
-6
-7
-8
-9
-10
-11
-12
-13
-14
-15
-16
-17
-18
-1.0
Vg = -5V
Vg = -4V
Vg = -3V
Vg = -2V
Vg = -1V
Vg = 0V
-0.5
average =-8,58nA
0.0
0
10
20
time (sec)
dDDα6T / 1-hexanol, on current
0 1 2 3 4 5 6 7 8 9 10 11 12
# of replicates
Stnd dev < 2%
Cycle number
ΔI(nA)
ΔI(nA) (+)citronellolo
0.05
60
0.00
-0.05
40
-0.10
-0.15
20
0
0
10
time (sec)
SIF – XCIV Congresso Nazionale – Genova 23.09.08
20
The role of grain boundaries
Correlation between Oligothiophene Thin Film Transistor Morphology and Vapor Responses L. Torsi, A.
A. J.
Lovinger, B. Crone, T. Someya, A. Dodabalapur, E. Katz, A. Gelperin,
rin,
Journal
of
Phys.
Chem.
B,
2002,
106,
12563
Gelpe
SIF – XCIV Congresso Nazionale – Genova 23.09.08
2D Field-induced conductance
Field-effect Conduttance (S)
-8
10
5
10
15
20
40
45
50
-9
10
-10
10
OS
-11
10
SS
D
SiO2
G
0
-20
-40
-60
-80
-100
Vg(V)
M.C. Tanese et al. , Thin Solid Films, 516, 3263–3269, (2008)
A. Dodabalapur, L. Torsi and H.E. Katz, Science 268, 270, 1995
SIF – XCIV Congresso Nazionale – Genova 23.09.08
Device Operation regimes
VGS< 0
accumulation mode
VGS = 0
LUMO
p-type
active
layer
VGS> 0
depletion mode
Ψs
Ψs
HOMO
++
++
Gate
contact
+
++
+++
Gate
Dielectr.
2D-transport
region
(a)
(b)
(c)
SIF – XCIV Congresso Nazionale – Genova 23.09.08
2D sensing response
8
7
95 nm
290 nm
470 nm
950 nm
S
D
SiO2
Si
G
ΔI(nA)
6
5
4
Vgs = -50 V
3
2
1
0
0
5
10
15
20
25
30
35
β-Citronellol [ppm]
• Ellipsometry: no swelling
• QCM: mass up-take
• Ea increases upon exposure to analyte
(A. Dodabalapur. et al. SPIE Optics and Photonics 2007 - 26-30 August, San Diego, CA)
SIF – XCIV Congresso Nazionale – Genova 23.09.08
Sensing mechanism
G
S
D
Vds
Vgs
2
SiO
2
Highly doped Si substrate
Ids
Ids
Vds = const
EB
Vds & Vgs = const
Grain surface
t
Vgs
SIF – XCIV Congresso Nazionale – Genova 23.09.08
Sensing measurements on OTFT
-10
1x10
Tran-characterisics
Tran-characterisicsin
in
NN2
1x10
Citronellol
30 ppm
Ids (nA)
-6
|I (A)|
-8
-8
-9
N2
2
-10
1x10
ΔI
-11
10
-4
0
-20
-40
Vg(V)
-60
-80
-2
TransTranscharacteristics
characteristicsin
in
citronellol
(S)(S)-(-)-β-citronellol
citronellol
(a)
0
|ΔI| (A)
Vds = -40 V
10-9
0
-20
-40
-60
-80
ΔΙ
ΔΙresponse
response
10-10
(b)
0
-20
-40
Vg (V)
-60
-80
L. Torsi, G.M. Farinola et al, L. Torsi, G.M. Farinola, M.C. Tanese, O. Hassan Omar, L. Valli, F.
Babudri, F. Palmisano, P.G. Zambonin & F. Naso. Nature Materials 7 (5), 412-417 (2008)
Patent Filed FT/TS/GV/ds/06578D53
SIF – XCIV Congresso Nazionale – Genova 23.09.08
PTA OTFT sensor for citronellol
Receptor:
amino acid
PTA / citronellol
-3,0
(S)-(-)-β-citronellol
(S)-(-)-β-citronellol
Analytes: Citronellol
enantiomers
ΔI (nA)
-2,5
-2,0
Vg = -100 V
-1,5
Racemate
Racemate
-1,0
(R)-(+)-β-citronellol
(R)-(+)-β-citronellol
-0,5
OH
OH
(+)
(-)
0,0
0
5
10 15 20 25 30 35
β-citronellol [ppm]
SIF – XCIV Congresso Nazionale – Genova 23.09.08
PTG OTFT sensor for carvone
Receptor:
glucose
Analytes: Carvone
(+)
(-)
ΔI (nA)
PTG / carvone
-14
-12
-10
-8
-6
-4
-2
0
0
(R)-(-)-carvone
(R)-(-)-carvone
(S)-(+)-carvone
(S)-(+)-carvone
20
40
60
80
carvone (ppm)
Vg = -100 V
SIF – XCIV Congresso Nazionale – Genova 23.09.08
100
Sensitivity enhancement
responses @ fixed gate bias
(R)-(+)-β-citronellol
(S)-(-)-β-citronellol
-2.0
-1.5
-1.0
-0.5
m
0
5
10 15 20 25 30 35
β-citronellol [ppm]
(R)-(+)-β-citronellol
(S)-(-)-β-citronellol
1E-10
m (A/ppm)
ΔI (nA)
-2.5
0.0
sensitivity vs. gate bias
1E-11
1E-12
1E-13
1E-14
20
0
-20
-40
-60
-80 -100
Vg (V)
three order of magnitude
enhancement !!!
L. Torsi, G.M. Farinola et al, Nature Materials 7 (5), 412-417 (2008)
SIF – XCIV Congresso Nazionale – Genova 23.09.08
DH-α6T / butanol
m (A/ppm)
1E-9
L = 0.2 mm
L = 1 mm
1E-10
1E-11
1E-12
1E-13
20
0
-20 -40 -60 -80 -100
Vg (V)
L. Torsi F. Marinelli, M. D. Angione, A. Dell’Aquila, N. Cioffi,
E. De Giglio and L. Sabbatini, submitted 2008
SIF – XCIV Congresso Nazionale – Genova 23.09.08
Role of contact resistance
S
D
DH-α6T
SiO2
Si
Rc
G
Rch
SIF – XCIV Congresso Nazionale – Genova 23.09.08
Rch and Rc: transfer line method (N2)
S
D
G
SiO2
DH-a6T
RW (MΩ cm)
8
6
Vg=-20 V
Vg= -40 V
Vg= -60 V
Vg=-80 V
Vg= -100 V
4
2
Si
0
0.0
0.2 0.4 0.6 0.8 1.0
Channel Lenght - (mm)
SIF – XCIV Congresso Nazionale – Genova 23.09.08
Rch and Rc: transfer line method
(Butanol)
8
S
G
SiO2
Si
D
RW (MΩ cm)
DH-a6T
6
Vg= -20 V
Vg= -40 V
Vg= -60 V
Vg= -80 V
Vg=-100V
4
2
0
0.0 0.2 0.4 0.6 0.8 1.0
Channel Lenght - (mm)
SIF – XCIV Congresso Nazionale – Genova 23.09.08
ΔR(MΩ)
DH-α6T / butanol
L=0.2 mm
L=0.6 mm
L=1 mm
ΔRc
1
0.1
-20 -40 -60 -80 -100
Vg(V)
SIF – XCIV Congresso Nazionale – Genova 23.09.08
DH-α6T / butanol
m (A/ppm)
1E-9
L = 0.2 mm
L = 1 mm
1E-10
1E-11
1E-12
1E-13
20
0
-20 -40 -60 -80 -100
Vg (V)
L. Torsi F. Marinelli, M. D. Angione, A. Dell’Aquila, N. Cioffi,
E. De Giglio and L. Sabbatini, submitted 2008
SIF – XCIV Congresso Nazionale – Genova 23.09.08
What will the future be like?
Affymax DNA chip
http://bmel.korea.ac.kr/image/intro_fig_5_4.gif
Low cost, low power, disposable electronic sensing system
Implemented on flex substrate (plastic, fabric, paper)
SIF – XCIV Congresso Nazionale – Genova 23.09.08
Conclusions
•OTFT sensor are very sensitive devices: enantiomeric
differential detection @ ppm
• Gate induced sensitivity enhancement
• Excellent repeatability but reproducibility is still an
issue
• Spurious effects are under control
• Future is likely to be in all-electronic disposable biosystems on cheap & flex substrates
SIF – XCIV Congresso Nazionale – Genova 23.09.08
Ringraziamenti
G.P Suranna, G. Romanazzi, P. Mastrorilli e C. F. Nobile
Dipartimento di Ingegneria delle Acque e di Chimica – Politecnico di Bari
A. Luzio1 and B. Pignataro2
1 PLAST_ICS
- Superlab - Consorzio Catania Ricerche - Catania
2 Dipartimento di Chimica Fisica - Università degli Studi di Palermo - Palermo
G.M. Farinola, P. Iliade, H. Hassan Omar, F. Babudri, F. Naso
Dipartimento di Chimica - Università degli Studi di Bari
G. Giancane and L. Valli
Università del Salento. Lecce
MIUR - PRIN 04 - 2004034021
SIF – XCIV Congresso Nazionale – Genova 23.09.08