The current-voltage (I-V) and capacitance-voltage (C-V) characteristics of Al/p-Si diode without and with rubrene layer fabricated by spin coating method have been investigated. From analyzing the I-V measurements for Al/p-Si diode, the basic device parameters such as barrier height, ideality factor and series resistance were extracted and then compared with the value which calculated from the I-V measurements for Al/rubrene/p-Si diode at room temperature. Also, the barrier height, built-in potential, concentration of ionized donors, and some other parameters of diode were found using C-V measurements. The barrier height values of 0.649 and 0.771 eV and ideality factor values of 1.22 and 1.51 were calculated using I-V measurements for diodes without and with rubrene layer, respectively. It has been seen that the rubrene layer raises the barrier height value of the device since this layer generates the physical barrier between p-Si and Al. By using C-V measurement of the Al/rubrene/p-Si diode, the barrier height value has been found as 0.820 eV. The energy distribution of the interface state density of device with rubrene layer determined from I-V characteristics increases exponentially with bias from 8.72 × 10 9 to 2.43 × 1011 cm-2 eV-1. © 2013 Elsevier B.V.