Analysis of the dielectric relaxation and ac conductivity behavior of polyvinyl alcohol‐cadmium selenide nanocomposite films

Abstract

We adopt an analytical approach to study the dielectric relaxation and ac conductivity behavior of the polyvinyl alcohol (PVA) -Cadmium Selenide (CdSe) nanocomposite films in the frequency range 100 Hz £ f £ 1 MHz and in the temperature range 298 K £ T £ 420 K. The CdSe nanoparticles are synthesized via a simple wet chemical route and are then impregnated into the polyvinyl alcohol matrix by 0.5 wt%, 1 wt%, and 4 wt%. About 1.7 times increase in effective permittivity (at 100 KHz) for the 4 wt% nanoparticle impregnated sample is observed from the analysis of the dielectric reinforcement function, which is attributed to the occurrence of interfacial polarization. It is found that the Cole-Cole model with a dc conductivity correction term can well fit the permittivity data. We have found that the dielectric relaxation time increases with increase in nanoinclusion into the matrix but decreases with increase in temperature. However, the space charge carrier conductivity and free charge carrier conductivity increase either with increase in nano inclusions or with increase in temperature. AC conductivity behavior have been analyzed considering the Jonscher power law and Dyre's random free energy barrier model, which reveals lowering of the maximum barrier height and correlated barrier hopping as the prevalent charge transport mechanism for the nanocomposites. Electric modulus study indicates similar conductivity relaxation dynamics for the nanocomposites but the responses deviate appreciably from the simulated ideal Debye responses. POLYM. COMPOS., 00:000-000, 2015.

Structural, morphological, thermal, dielectric, and electrical properties of alumina nanoparticles filled PVA–PVP blend matrix‐based polymer nanocomposites

“…The PVA and PVP films have very low electrical conduction due to which these are frequently used as a dielectric material for electrical insulation in organoelectronic devices [33][34][35]. The hydroxyl (AOH) and carbonyl (C @ O) functional groups of the PVA and PVP backbone, respectively, exhibit electrostatic interactions with the additives and inorganic nanofillers, and therefore, these hydrophilic polymers are mostly preferred as binders and capping agents in the preparation of advanced composite functional materials [14,[36][37][38][39]. In addition to the pristine polymers, the blend of PVA and PVP realizes its giant applications in the area of electronics, electrical, and biomedical engineering and also in the preparations of various kind of sensors and the energy storing devices [7,18,19,23,[40][41][42][43][44][45].…”

Optimized polyaniline‐transition metal oxide composites: A comparative study of alternating current conductivity via correlated barrier hopping model

“…So, variation of s with temperature for each sample was studied and found that in each case, s decreased with increase in temperature ( Fig. 10) decisively suggesting that AC conduction mechanism in all the samples can be clearly understood through CBH model [38,75]. According to this model, charge transport is suggested to be due to thermal activation over the barrier between two sites, each having a coulombic potential well associated with it.…”

Structural dependent, dielectric and conduction analysis of CdSe based quantum dots

“…Effective permittivity ( ′ ), decreases with increase of frequency ( Fig. 5b) whereas at higher frequencies dipoles can no longer follow the field, as a result of which, effective permittivity decreases [11]. At higher frequencies, dipoles slowly fall off the electric field [30] which leads to decrease in dielectric amount [38,39].…”

“…Many of these applications are greatly benefited by existence of quantum dots with their extensive and unique properties. For instance, dielectric characteristics of QDs can enhance the electro-optical properties of nano-composites like, liquid crystals [9,10], polymer matrix [11][12][13], graphene and hybrid graphene [14][15][16]. Polymeric nano-composites consisting of conductive nanoparticles are mostly used in electronic devices offering wide and low-budget fabrication techniques.…”

“…At the meantime, addition of QDs in nano-composite liquid crystals, paves the way improving their dielectric, optical and electro-optical properties. It has shown in literatures that, in some cases dispersion of CdSe based QDs in nanocomposite reduces the relative permittivity [9], whereas in some, this value is enhanced after addition of CdSe based QDs [11][12][13]. Therefore, understanding of the quantum dots electrical properties and their interaction with variety of matrices, help fabricating of efficiently enhanced electronic devices.…”