Au/PPy/n-Si (MPS) type Schottky barrier diodes (SBDs) were produced and their current-voltage (I-V) characteristics were measured in the positive and negative bias regions at 300 K. The basic electronic quantities such as reverse-saturation current (I-o ), ideality factor (n), zero-bias barrier height (Phi(B0) ), series (R-s) and shunt resistances (R-sh) were obtained by using I-V data in total darkness and illumination (100 W/m(2)). The values of these parameters were found as 7.79 x 10(-9) A, 5.41, 0.75 eV, 1 k Omega and 130 M Omega in dark) and 4 x 10(-9) A, 4.89, 0.77 eV, 0.9 k Omega and 1.02 M Omega under illumination), respectively. Also the energy density distribution behaviors of surface states (N-ss ) have been acquired by calculation of effective barrier height (Phi(e) ) and ideality factor n (V) depending on voltage in total darkness and illumination. The values of N (ss) show an exponentially increase from the mid-gap of Si to the lower part of conduction band (E-c ) for two conditions. The possible current conduction mechanisms were determined by plotting of the double logarithmic I-V plots in the positive voltage zone and the value of current was found proportional to voltage (I similar to V (m) ). The high values of n and R-s were ascribed to the certain density distribution of N-ss localized at semiconductor /PPy interface, surface conditions, barrier inequality, the thickness of PPy interlayer and its roughness. The open-circuit voltage of the photodiode was found as 0.36 V under 100 W/m(2) illumination level. This is evidence that the fabricated sample is very sensitive to illumination. Therefore, it can be put into practice in optoelectronic industries as a photodiode or solar cells.