Hopping transport in doped conducting polymers in the insulating regime near the metal-insulator boundary: polypyrrole, polyaniline and polyalkylthiophenes

Yoon, C.O.; Reghu, M.; Moses, D.; Heeger, Alan J.; Cao, Yang; Chen, T.-A; Wu, Xiang‐Fa; Rieke, Reuben D.

doi:10.1016/0379-6779(96)80013-0

Cited by 174 publications

(86 citation statements)

References 38 publications

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“…The values (up to 100 meV at the lowest p) are large cf. conventional inorganic semiconductors, an observation that was previously used to argue for some form of inter-cluster hopping over ES VRH 9 . As discussed above, we believe the evidence for ES VRH is overwhelming here; we rather interpret the high T ES and D C in terms of the low k values in semiconducting polymers via D C ¼ e 3 N(E F ) 1/2 /k 3/2 .…”

Section: Electrochemical Thin Film Transistorsmentioning

confidence: 97%

“…A similar T dependence can, however, also be obtained from thermally assisted tunnelling between nanoscopic conductive regions in a more insulating matrix, due to the Coulomb penalty associated with single carrier charging 30 . Such models have been adapted to semiconducting polymers 8 and claims of observation of this mechanism have been made 9 . We thus performed additional analyses and measurements to clarify the origin of the T À 1/2 behaviour.…”

Section: Electrochemical Thin Film Transistorsmentioning

confidence: 99%

“…Elusive issues include the non-trivial influence of the multiple sources of disorder (for example, semi-crystallinity, paracrystallinity and nanoscale inhomogeneity [1][2][3][4][5][6][7], the elucidation of the important hopping mechanisms [1][2][3][4][7][8][9][10] , the effects of charge carrier-lattice interactions 3,4 and the identification of the ultimate limits on conductivity and mobility [1][2][3][4][5][6]11 . The latter is particularly important as, in addition to being of considerable fundamental interest the upper limits on conductivity and mobility also limit device performance (for example, transistor output current and operating frequency).…”

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confidence: 99%

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Hopping transport and the Hall effect near the insulator–metal transition in electrochemically gated poly(3-hexylthiophene) transistors

et al. 2012

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Despite 35 years of investigation, much remains to be understood regarding charge transport in semiconducting polymers, including the ultimate limits on their conductivity. Recently developed ion gel gating techniques provide a unique opportunity to study such issues at very high charge carrier density. Here we have probed the benchmark polymer semiconductor poly(3-hexylthiophene) at electrochemically induced three-dimensional hole densities approaching 10 21 cm À 3 (up to 0.2 holes per monomer). Analysis of the hopping conduction reveals a remarkable phenomenon where wavefunction delocalization and Coulomb gap collapse are disrupted by doping-induced disorder, suppressing the insulator-metal transition, even at these extreme charge densities. Nevertheless, at the highest dopings, we observe, for the first time in a polymer transistor, a clear Hall effect with the expected field, temperature and gate voltage dependencies. The data indicate that at such mobilities (B0.8 cm 2 V À 1 s À 1 ), despite the extensive disorder, these polymers lie close to a regime of truly diffusive band-like transport.

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Section: Electrochemical Thin Film Transistorsmentioning

confidence: 97%

Section: Electrochemical Thin Film Transistorsmentioning

confidence: 99%

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confidence: 99%

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Hopping transport and the Hall effect near the insulator–metal transition in electrochemically gated poly(3-hexylthiophene) transistors

et al. 2012

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“…Possible non-CDW realizations include arrays of relatively distant 1D conductors, e.g., quantum wires, nanotubes, 43 or polymers. 44 As elaborated in Sec. I, impurities divide the system into a collection of metallic rods.…”

Section: B 3d Systems With Large Impurity Concentrationsmentioning

confidence: 99%

“…At low and moderate doping the T -dependence of the conductivity often resembles ES and/or Mott VRH laws, see a short review in Ref. 44. A systematic study of the VRH conductivity dependence on doping has been attempted by Aleshin et al 60 In those experiments doping of PEDT/PSS samples was varied by controlling the pH of the solution at the sample preparation stage.…”

Section: Conclusion and Comparison With Experimentsmentioning

confidence: 99%

Variable-range hopping in quasi-one-dimensional electron crystals

2004

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We study the effect of impurities on the ground state and the low-temperature Ohmic dc transport in a one-dimensional chain and quasi-one-dimensional systems of many parallel chains. We assume that strong interactions impose a short-range periodicicity of the electron positions. The longrange order of such an electron crystal (or equivalently, a 4kF charge-density wave) is destroyed by impurities, which act as strong pinning centers. We show that a three-dimensional array of chains behaves differently at large and at small impurity concentrations N . At large N , impurities divide the chains into metallic rods. Additions or removal of electrons from such rods correspond to charge excitations whose density of states exhibits a quadratic Coulomb gap. At low temperatures the conductivity is due to the variable-range hopping of electrons between the rods. It obeys the Efros-Shklovskii (ES) law − ln σ ∼ (TES/T ) 1/2 . TES decreases as N decreases, which leads to an exponential growth of σ. When N is small, the metallic-rod (also known as "interrupted-strand") picture of the ground state survives only in the form of rare clusters of atypically short rods. They are the source of low-energy charge excitations. In the bulk of the crystal the charge excitations are gapped and the electron crystal is pinned collectively. A strongly anisotropic screening of the Coulomb potential produces an unconventional linear in energy Coulomb gap and a new law of the variable-range hopping conductivity − ln σ ∼ (T1/T ) 2/5 . The parameter T1 remains constant over a finite range of impurity concentrations. At smaller N the 2/5-law is replaced by the Mott law, − ln σ ∼ (TM /T ) 1/4 . In the Mott regime the conductivity gets suppressed as N goes down. Thus, the overall dependence of σ on N is nonmonotonic. In the case of a single chain, the metallic-rod picture applies at all N . The low-temperature conductivity obeys the ES law, with log-corrections, and decreases exponentially with N . Our theory provides a qualitative explanation for the transport properties of organic charge-density wave compounds of TCNQ family.

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Electrical resistivity and magnetoresistivity of protonic acid (h2SO4 and HCl)-doped polyaniline at low temperature

Ghosh

Barman

Meikap

et al. 2000

J. Appl. Polym. Sci.

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Electrical-transport properties of protonic acid (H 2 SO 4 and HCl)-doped polyaniline (PANI) in an aqueous ethanol medium were investigated in the temperature range 1.8 K Յ T Յ 300 K and in a magnetic field up to 8 T. The room-temperature resistivity of HCl-doped PANI is larger than that of H 2 SO 4 -doped PANI. The resistivity ratios r ϭ (1.8 K)/(300 K) of the samples are high. The samples in the insulating region show a crossover from a Mott to an Efros-Shklovskii variable range hopping conduction at T ϭ 9.8 K for H 2 SO 4 -doped PANI and 8.5 K for HCl-doped PANI. The magnetoresistivity of these samples is also explained by the variable range hopping theory. The different physical parameters were calculated from the experimental data.

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Hopping transport in doped conducting polymers in the insulating regime near the metal-insulator boundary: polypyrrole, polyaniline and polyalkylthiophenes

Cited by 174 publications

References 38 publications

Hopping transport and the Hall effect near the insulator–metal transition in electrochemically gated poly(3-hexylthiophene) transistors

Hopping transport and the Hall effect near the insulator–metal transition in electrochemically gated poly(3-hexylthiophene) transistors

Variable-range hopping in quasi-one-dimensional electron crystals

Electrical resistivity and magnetoresistivity of protonic acid (h2SO4 and HCl)-doped polyaniline at low temperature

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