Measurements of current-voltage curves at room temperature, in nitrogen and nitrogen-acetone atmospheres have clearly demonstrated the rectifying behavior of the Al/PPy-DBSA/Au structure. For this structure, the values of 0.82 eV and 2.31, for the barrier height and ideality factor, respectively, have been obtained in nitrogen atmosphere, while at concentration of 120 ppm of acetone, the corresponding values were 0.74 eV and 2.07. The barrier height value obtained from I-V characteristic is lower than the barrier height value obtained from C-V measurements. The discrepancy can be due to the existence of an interfacial oxide layer between the semiconductor and Schottky contact metal. The density distribution curves of the interface states vary in the range (0.55-E V ) to (0.84-E V ) for pure nitrogen, and (0.45-E V ) to (0.60-E V ) in atmosphere with acetone. The interface state density has an exponential rise with bias from the midgap towards the top of the valence band of the PPy-DBSA.