Charge carrier relaxation studies in poly (3, 4-ethylenedioxythiophene) nanofibers

Abstract

The electrical conductivity and carrier relaxation in poly (3, 4-ethylenedioxythiophene) (PEDOT) nanofibers have been studied over a wide range of frequency and temperature by means of impedance spectroscopy. High resolution transmission electron micrographs confirm the formation of nanofibers with average diameter of 14 nm. The linear increase of imaginary permittivity with decreasing frequency in the loglog plot of ε″ versus ω is attributed to the higher contribution of dc conductivity than that of the electrode polarization. The presence of single semicircle in the complex impedance ColeCole plot indicates the presence of single charge carrier relaxation mechanism. The perfect matching of the relaxation peak in Z″ and M″ vs. frequency at different temperature confirms the presence of Debye type relaxation. From the temperature dependent behavior of frequency exponent study it is confirmed that the charge transport takes place through correlated barrier hopping mechanism. Decrease of barrier height and increase of density of states with increasing dopant concentration can be corroborated with the conductivity enhancement.

Functional solid additive modified PEDOT:PSS as an anode buffer layer for enhanced photovoltaic performance and stability in polymer solar cells

“…These results indicate that the incorporation of DOH into the PEDOT:PSS rearranged the PEDOT and PSS chains, while the smoother buffer layer on top of the ITO improved the connection between the PEDOT-rich regions in both the parallel and vertical directions33. The phase separation between PEDOT and PSS chains provided efficient charge carrier hopping leading to superior hole transport pathways34.…”

Investigation of dielectric properties of free standing electrospun nonwoven mat

“…Frequency‐assisted dielectric at various temperatures is plotted in Figure (a) which shows an intensified dielectric constant for lower frequencies as well as higher temperature which is the consequence of temperature‐dependent polarization . The maximum temperature was confined to 50 °C since PVA has the glass transition temperature in the range of 50–60 °C .…”

Dielectric investigation of a conducting fibrous nonwoven porous mat fabricated by a one-step facile electrospinning process

“…In CBH model, value of S shows the decreasing behaviour with increasing temperature and vice versa which suggests small polaron model. [39][40][41] In this study, AC conductivity spectra were tted to eqn (3) to evaluate the value of frequency exponent (S) as shown in Table 2. Decreasing trend of S from near unity to zero value was observed with increasing temperature from À40 C to 60 C. This trend of S with respect to the temperature ensures that the CBH model is the best suited model for demonstrating the charge conduction mechanism for AC conduction in the nanobers and the similar behaviour was already observed for the lms of erbium-, gadolinium-and lanthanum-doped PVA and PVA-selenium nanocomposites.…”

“…3a) displays an enhancement of the dielectric constant at low frequency and at higher temperature, as a consequence of the temperature dependent interfacial polarization or electrode polarization. 41 The maximum temperature was restricted to 60 C as the glass transition temperature of PVA is 70 C. 36 The reason behind the increased value of dielectric constant is due to the increase in segmental mobility of the molecule at higher temperatures. 58 This increase can also be attributed to the restriction of the ion clusters and ion aggregation in the mat at higher temperatures.…”

“…3 o is permittivity of free space, W eff and W m are effective and maximum barrier height respectively, r measures distance between defects, n ¼ 1 and n ¼ 2 suggest single polaron and bi-polaron hopping respectively. The AC conductivity for CBH model in relation with R H (hopping distance) and N ¼ k B TN(E f ) (density of state) is expressed by:41 …”