In this study, the current-voltage characteristics of non-doped and distinct graphene (Gr)-doped polyvinyl alcohol (PVA) interlayers in metal/organic polymer semiconductor type Schottky junction structures (SJSs) were investigated on both forward and reverse biases under distinct levels of illumination. The distinct doping concentration ratios (1%, 3% and 7%) of the Gr added to the PVA interlayers were compared by taking into account the basic electrical parameters, such as saturation current (I-o), ideality factor (n), barrier height (phi(Bo)), series (R-s) and shunt resistance (R-sh). The 7% Gr-doped structure displayed the lowest I-o values at zero bias. Moreover, the results indicated that the 7% Gr-doped PVA decreased the n value but increased the phi(Bo) value compared with values associated with structures that have different doping concentrations. In terms of quality and reliability, the R-s and R-sh values of the SJSs were obtained using Ohm's law and Cheung's functions, and the 7% Gr-doped structure eventually displayed more uniformly distributed and lower R-s values and the highest R-sh values. Consequently, the 7% Gr-doped structure had better overall quality because of its superior electrical properties compared with structures that have other doping concentrations. Therefore, the 7% Gr-doped structure can be used as a photodiode in electronic devices.