Electrical properties of polyacetylene with various cis‐trans compositions

Abstract

The electrical conductivity of crystalline polyacetylene films having various cis-trans compositions was measured. The resistivity and the energy gap of a 92,5% trans polymer were 1,Ol .l@R.cm and 0,56 eV, respectively, whereas the values of a 20,0% trans polymer were 2,35.10* R . cm and 0,93 eV, respectively. These differences are discussed in terms of the effective conjugation length estimated from visible spectra and ESR measurements, and the spacing between molecular planes obtained by x-ray diffraction measurements.

Synthesis and Properties of Semiconducting and Metallic Derivatives of Polyacetylene, (Ch)x

“…8 This is consistent with the transport in undoped (CA)x being dominated by trace impurities or defects. Ochinnikov 1 7 has argued that the energy gap extrapolated to infinite chain polyenes is too large to be accounted for by simple band theory of the bond-alternated chain, and he therefore concluded that Coulomb correlations play an important role.…”

“…8 pointed out that the room temperature conductivity of crystalline films gf poliaceiylene depended on the cistrans content, vsrying from 10 " ohm-cm for the trans material to 10 -9 ohx'lcm " for the cis-isomer. In view of the sensitivity of polyacetyleneot%impurities and/or defects as demonstrated by our doping studies, it appears likely that the intrinsic conductivity of pure polyacetylene is even lower.…”

Electrical transport in doped polyacetylene

“…In the dilutl limit, the transport is via carrier hopping; the mobility is small (-5x10-cm /V sac) and activ I it ~ ted (AE-0.3 eV). 20. and leads to a qualitative change in temperature dependence of the conductivity and to finite zero temparture values above y,= 0 .…”

Polymerization of Methylpentynes by Transition Metal Catalysts: Monomer Structure, Reactivity, and Polymer Properties

“…iv) The electrical conductivities of compressedpellet samples were [10][11][12][13][14][15][16][17][18] ohm-1 cm-1 or lower. When the semiconductivity (10-9 -10-5 ohm-1 em -I) of polyacetylene 12 is taken into account, the presence of alkyl group(s) as side chain twists the main chain to greatly reduce conductivity.…”