© 2020 Elsevier GmbHThe fabricated structure based on organic magnesium phthalocyanine material for solar cells is investigated. Such device is fabricated by a facile spin coating route. It is observed that negative values of capacitance (NC) and dielectric constant are exhibited within the forward voltage at adjustable frequencies ranges of 500 KHz-1 MHz. In order to understand the mechanism and the behaviour of such device, the capacitance voltage and conductance voltage characteristics in terms of frequency are studied. Based on impedance spectroscopy measurements, the real and imaginary parts of impedance are frequency dependent. The electrical conductivity in terms of voltage of organic diode is investigated within −2 V, +5 V bias voltage range at 500 kHz and 1 MHz. The average of conductivity about 2μ S/cm is then recorded. Many parameters causes the negative capacitance and dielectric constant.