The aim of this study was to analyze the interface states (N-ss) in pure Al//p-Si/Al, Al/N-F Nft/p-Si/Al and Al/N-T Nft/p-Si/Al Schottky barrier diodes (SBDs). N-Substituted 1,8-naphthalimide thin films were deposited on a p-Si substrate by spin coating and annealed at approximate to 200 degrees C for 60 s under an air atmosphere. Al contacts were obtained via reactive magnetron sputtering. The current voltage (I-V) characteristics of the SBDs were measured at room temperature. From the I-V characteristics, the SBDs ideality factor (n) and zero-bias barrier height values (phi(b)) of 1.27, 1.00, and 1.05 and 0.66 eV, 0.70 eV, and 0.64 eV were observed for the Al//p-Si/Al, Al/N-F Nft/p-Si/Al and Al/N-T Nft/p-Si/Al Schottky barrier diodes, respectively. The interface state density distribution profile (N-ss) as a function of (E-ss-E-v) was extracted from the forward-bias I-V measurements by considering the effective barrier height and (phi(e)) and series resistance (R-s) of the Schottky diode. The obtained N-ss plot tendency showed that the existence of interface states has no significant effect on the rectifying and capacitance characteristics. The N-ss values with the 1,8-naphthalimide layer were lower than that without it. This shows that naphthalimide exhibits a strong contribution by blocking the unwanted states and some traps in the conduction mechanism, which may cause possible cracks or deep paths for carriers to travel along the junction.