(a) Chemical structures of the used materials. Left: Fullerene , right: Copper-phthalocyanine . (b) Top view of the ring-type transistor (left) and ring-type inverter (right). The silicon substrate acts as the gate electrode in both cases. (c) Electrical circuit of the used inverters.
Output characteristics of unipolar field-effect transistors with (a) and (b) and corresponding transfer characteristic for (c) and for (d). The substrates were treated and the films evaporated at 375 K substrate temperature. The direction of the hysteresis is indicated by arrows.
Output characteristics of ambipolar field-effect transistors for a mixing ratio between and of in the -channel (a) and the -channel regime (b) together with the corresponding transfer characteristics in the -channel (c) and the -channel regime (d). The substrate was treated and the film was evaporated at 375 K substrate temperature. The direction of the hysteresis is indicated by the arrows.
The square root of the drain current vs the gate voltage of unipolar field-effect transistors with and (a) and the film with a mixing ratio of (with raw data from Figs. 2 and 3). The gray lines are linear fits from which the mobilities were determined.
Dependence of the mobility on the mixing ratio for different substrate temperatures during organic film deposition (300 and 375 K). The mobilities are determined from the measurements in the saturation regime. Open symbols are related to the hole mobilities and filled symbols to the electron mobilities. The gray lines are linear fits conducing to explicitness.
Scanning force microscopy images taken in noncontact mode for pure and films as well as for three mixed films grown at 375 K. The total image size is . The height scale (HS) is given as the difference between the lowest value (black) and the highest value (white) in each of the images.
Dependence of the threshold voltage on the mixing ratio for different temperatures during organic film evaporation (300 and 375 K). The threshold voltages are determined from the measurements in the saturation regime. Open symbols are related to the threshold voltages for the holes and filled symbols to the threshold voltages for the electrons. The gray lines are connecting the average values for both treatments and conduce to clarity.
Characteristics of ambipolar inverters with mixing ratios of (a) and 1:3 (b) at a driving voltage. Transfer characteristics (top) and current dissipation (bottom) are shown. The substrates were treated and the films were evaporated at 375 K substrate temperature.
Transfer characteristics (top) and current dissipation (bottom) of a complementary inverter consisting of discrete and transistors. The insets present the circuit and the sign of the driving voltage used to operate the inverter in the first and the third quadrant. The substrate was treated and the film was evaporated at 375 K substrate temperature.
Simulations of ambipolar and complementary inverter transfer characteristics and current dissipation with symmetric parameters (mobility and threshold voltage) for the - and the -channel in (a), in comparison to asymmetric mobilities and symmetric threshold voltages in (b).
Extracted parameter values (mobility and threshold voltage) for different mixing ratios determined from saturation and the ambipolar regime. Part of the fit curves is also shown in Fig. 4.
Article metrics loading...
Full text loading...