Abstract
We demonstrate ambipolar charge transport in organic field-effect transistors based on the solution processible methanofullerene [6,6]-phenyl-
C
71
-butyric acid methyl ester ([70]PCBM). The electron mobility measured in the linear and saturated regimes is approximately equal and of the order of
1
×
10
−
3
cm
2
∕
V
s
. In the linear regime, mobility is thermally activated with a strong gate bias dependence. The
p
-channel hole mobility is lower with a maximum value of
2
×
10
−
5
cm
2
∕
V
s
. The
n
- and
p
-channel operations are characterized by a low
(
∼
∣
3
∣
V
)
and a high
(
∼
∣
50
∣
V
)
switch-on voltage, respectively, with the on-off current ratio on the order of
10
4
for both channels. Although the present findings are qualitatively similar to those reported previously for
C
60
-methanofullerene-based transistors, [70]PCBM devices are more stable and easier to reproduce. By making use of this property we are able to demonstrate functional unipolar and complementarylike logic circuits with promising operating characteristics.