n-Si/p-PEDOT-PSS heterojunction diode was fabricated by deposition of poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) onto n-type Si wafer using spin coating. Its electrical properties of the diode were investigated by current-voltage (I-V) and capacitance-voltage (C-V) measurements. The field emission scanning electron microscopy (FE-SEM) was used to determine the surface quality. SEM result indicates that the surface morphology of the PEDOT-PSS film spin coated on n-Si substrate is almost homogeneous. Diode parameters such as the ideality factor, barrier height and series resistance were calculated using Cheung's method and C-V measurements. characteristics under dark and illumination conditions were performed to characterize the photovoltaic behavior of the diode.