Poly[2-methoxy-5-(2′-ethylhexyloxy)-1,4-phenylene vinylene] MEH-PPV polymer-based heterojunction for organic electronics: Analysis using impedance spectroscopy

The electrical and dielectric properties of an Au/MEH-PPV/p-Si/Al heterojunction were investigated using impedance spectroscopy. The impedance spectra revealed Cole–Cole-type relaxation with a fractal exponent ([Formula: see text]) of 0.85, indicating nonideal charge dynamics modeled with a constant phase element. A remarkably high dielectric constant ([Formula: see text]) of 45 was measured at 1[Formula: see text]kHz, highlighting the device’s potential for charge storage applications. At frequencies above 1[Formula: see text]MHz, the device exhibited negative capacitance (NC), a signature of dynamic inductive effects arising from charge carrier trapping and relaxation at the organic–inorganic interface. This behavior corresponds to an L–C resonance near 1[Formula: see text]MHz, which is also marked by a minimum in the dielectric loss ([Formula: see text]). These findings demonstrate that the device’s frequency response is governed by a complex interplay of interface states, dipole polarization and series resistance.