Doping, density of states, and conductivity in polypyrrole and poly(p-phenylene vinylene)

Abstract

The evolution of the density of states (DOS) and conductivity as function of well controlled doping levels in OC1C10-poly(p-phenylene vinylene) [OC1C10-PPV] doped by FeCl3 and PF6, and PF6 doped polypyrrole (PPy-PF6) have been investigated. At a doping level as high as 0.2 holes per monomer, the former one remains non-metallic, while the latter crosses the metal-insulator transition. In both systems a similar almost linear increase in DOS as function of charges per unit volume (c * ) has been observed from the electrochemical gated transistor data. In PPy-PF6, when compared to doped OC1C10-PPV, the energy states filled at low doping are closer to the vacuum level; by the higher c * at high doping more energy states are available, which apparently enables the conduction to change to metallic. Although both systems on the insulating side show log σ ∝ T −1/4 as in variable range hopping, for highly doped PPy-PF6 the usual interpretation of the hopping parameters leads to seemingly too high values for the density of states.

Core level photoemission studies on conducting polypyrrole polymer nanotubes showing switching transitions

“…In the case of PPY films and nanotubes, it is known that a change in the doping level leads to the change in the density of states at the Fermi level N(E F ). 8,26 Thus, our results show a reduction in doping level on reduction of the diameter of PPY nanotubes as well as on gold incorporation. These findings are in concomitance to the findings of doping level change obtained from N 1s photoemission measurements.…”

A unified bottom up multiscale strategy to model gas sensors based on conductive polymers

“…3b). The conductivity, doping level and density of states of PH 6 doped polypyrrole and FeCl 3 doped poly(p-phenylene vinylene) were studied in group of Mennon [43]. The reported doping level dependences of conductivity are shown in Fig.…”

“…4. Polyppyrol was considered fully doped when the monomer charge reaches 0.25 [43,44] and the doping level is defined as the charge per 4 monomers. It turns out that the percolational behavior (4) describes also the doping level dependence of conductivity of these two ICPs, with the same threshold th ----0·204 for polypyrrole and smaller threshold th ----0·07 for poly(p-phenylene vinylene).…”

“…Doping level dependence of conductivity of polypyrrole and poly(pphenylene vinylene) at 300 K[43]. Lines are fits with (4) with th ----0.204, a = 10 5 S/m and th ----0.07, A = 10 4 S/cm, correspondingly.…”

The Electronic Structure of Organic Semiconductors

“…For technological applications, for example, as antistatic, anticorrosive, or conducting paint, a persistent, high, and homogeneous level of doping is required. Conductivities up to a few hundred Siemens per centimeter can be reached for the conducting polymers poly(aniline), poly(pyrrole) and PEDOT:PSS (poly(3,4-ethylene dioxythiophene)-polystyrene sulfonic acid), a mixture of two polymers [42][43][44][45][46][47][48] (Figure 1.7). A basic introduction to conducting polymers, focused on PEDOT:PSS, can be found in [49].…”