Top-gate all organic thin-film field-effect transistors are fabricated one-off by fully-evaporation method without breaking vacuum

which has many advantages. The fabrication technology simplifies the device processing

and avoids the spot due to the preparation condition change. By evaporation method preparing device

the every layer film thickness can be controlled rigorous

and the thinner

symmetrical

compact film layers are propitious to reduce the operation voltage and enhance the device on-current. The source-drain electrode can be prepared by conventional photolighography technique on the ITO coated glass substrates

and the active layer

insulator layer and gate electrode can be patterned by different shadow masks

which are propitious to scale down device dimension and enhance integration degree. When the OTFTs with topgate were used to integrated circuit or active-matrix OLED display

the above advantages will be more clearly. All-organic thin-film field-effect transistors (Device A) with pentacene/thin Teflon insulator film of 100 nm were successful fabricated

with operating voltage reach to 40V

threshold voltage VT=-8V and mobility μ=1.0×10

-2

cm

2

/V·s. As for Device B

with the thickness of Teflon insulator film decrease to 50 nm and the same process condition with that of Device A

the operating voltage fell to 10V

threshold voltage V

T

=-3Vand mobility μ=1.2×10

-2

cm

2

/V·s. The result indicates that thinner insulator film can reduce operation voltage observably. However

the mobility has no obvious change with the similar pentacene/Teflon interface performance due to the same process condition. When the OTFT (Device C) fabricated with PMMA (150nm) replacing Teflon as insulator layer

the threshold voltage of device was decreased to near 0V

and mobility was increased more 3 times than that of the previous devices

and the saturation current was also increased obviously. These results indicate that the appropriate organic insulator can be used to improve the interface performance of active layer/insulator layer interface

and improve the device mobility.