Dielectric Properties of PVK and Ferrocene-Doped Thin Films: A Study of Electric Conduction Modulation

This article discusses the dielectric properties of poly (9-vinylcarbazole) (PVK) and ferrocene-doped PVK thin films. The article discusses the preparation of the thin films and the measurement of their dielectric properties as a function of ferrocene concentration, frequency, and temperature. The poly (N-vinyl carbazole) (PVK) is a well-known hole transport polymer; therefore, this material is suitable for clarifying the effect of the injected holes on the breakdown process in polymer thin film. The thin films were grown by the isothermal solution casting technique. Dielectric properties of grown films were studied as function of ferrocene concentration, frequency, and temperature. The relative permittivity (ε') is increased with increasing ferrocene percentage (~1%) due to the free charge carriers. The relative permittivity decreases for higher ferrocene percentage (~2%). However, the relative permittivity of PVK and ferrocene-doped PVK samples remains almost constant for studied temperature range (313–413 K). The frequency dependence of tan σ for all samples is studied. The frequency dependence of dielectric parameter exhibits frequency dispersion behavior, which suggests all types of polarization present in the lower frequency range. The loss tangent (tan σ) values are larger at higher temperatures in the low frequency region. However, the tan σ values at different temperatures are almost similar in the high frequency region. It is observed that the relative permittivity is maximum, dielectric loss is minimum, and AC conductivity is minimum for 1% ferrocene doped PVK as compared to pure PVK and 2% ferrocene doped PVK samples. The temperature effect is more pronounced in the low-frequency region. The conductivity of PVK is increased as the ferrocene dopant concentration of increases up to 2%. The higher conductivity is related to the additional hopping sites for the charge carriers.