Editing Polyacetylene (section)

==Doping==
When polyacetylene films are exposed to vapors of electron-accepting compounds ([[p-type semiconductor|p-type]] [[dopant]]s), the [[electrical conductivity]] of the material increases by orders of magnitude over the undoped material.<ref name=Chiang>{{cite journal |last=Chiang |first=C.K. |author2=Gau, S.C. |author3=Fincher, C.R. |author4=Park, Y.W. |author5=MacDiarmid, A.G. |author6=Heeger, A.J. |title=Polyacetylene, (CH)<sub>x</sub>: n-type and p-type doping and compensation |journal=Appl. Phys. Lett. |date=1978 |volume=33 |issue=1 |page=18 |doi=10.1063/1.90166 |bibcode=1978ApPhL..33...18C}}</ref><ref name=":0">{{cite journal |last1=MacDiarmid |first1=Alan Graham |last2=Mammone |first2=R. J. |last3=Kaner |first3=R. B. |last4=Porter |first4=Lord |last5=Pethig |first5=R. |last6=Heeger |first6=A. J. |last7=Rosseinsky |first7=D. R. |last8=Gillespie |first8=Ronald James |last9=Day |first9=Peter |date=1985-05-30 |title=The concept of 'doping' of conducting polymers: the role of reduction potentials |url=https://royalsocietypublishing.org/doi/10.1098/rsta.1985.0004 |journal=Philosophical Transactions of the Royal Society of London. Series A, Mathematical and Physical Sciences |volume=314 |issue=1528 |pages=3–15 |doi=10.1098/rsta.1985.0004 |bibcode=1985RSPTA.314....3M |s2cid=91941666|url-access=subscription }}</ref> [[p-type semiconductor|p-Type]] [[dopant]]s include Br<sub>2</sub>, I<sub>2</sub>, Cl<sub>2</sub>, and AsF<sub>5</sub>. These [[dopant]]s act by abstracting an [[electron]] from the polymer chain. The [[ionic conductivity (solid state)|conductivity]] of these polymers is believed to be a result of the creation of [[charge-transfer complex]]es between the polymer and [[halogen]].<ref name=Shirakawa/> [[Charge-transfer complex|Charge transfer]] occurs from the polymer to the acceptor compound; the polyacetylene chain acts as a [[cation]] and the acceptor as an [[anion]]. The "hole" on the polymer backbone is weakly associated with the anionic acceptor by [[Coulomb potential]].<ref name=Chiang/> Polyacetylene doped with ([[p-type semiconductor|p-type]]) [[dopants]] retain their high conductivity even after exposure to air for several days.<ref name=Saxman/>

Electron-donating ([[n-type semiconductor|n-type]]) [[dopant]]s can also be used to create conductive polyacetylene.<ref name=":0"/> n-Type [[dopant]]s for polyacetylene include lithium, sodium, and potassium.<ref name=Saxman/> As with [[p-type semiconductor|p-type]] dopants, [[charge-transfer complex]]es are created, where the polymer backbone is [[anionic]] and the donor is [[cationic]]. The increase in conductivity upon treatment with an [[n-type semiconductor|n-type]] [[dopant]] is not as significant as those achieved upon treatment with a [[p-type semiconductor|p-type]] dopant. Polyacetylene chains doped with [[n-type semiconductor|n-type]] [[dopants]] are extremely sensitive to air and moisture.<ref name=Saxman/>

Polyacetylene can also be doped electrochemically.<ref name=":0"/>

The conductivity of polyacetylene depends on structure and doping. Undoped ''trans''-polyacetylene films have a conductivity of 4.4×10<sup>−5</sup> Ω<sup>−1</sup>cm<sup>−1</sup>, while ''cis''-polyacetylene has a lower conductivity of 1.7×10<sup>−9</sup> Ω<sup>−1</sup>cm<sup>−1</sup>.<ref name=":0"/> Doping with bromine causes an increase in conductivity to 0.5 Ω<sup>−1</sup>cm<sup>−1</sup>, while a higher conductivity of 38 Ω<sup>−1</sup>cm<sup>−1</sup> is obtained through doping with iodine.<ref name="Shirakawa"/> Doping of either ''cis''- or ''trans''-polyacetylene leads to an increase in their conductivities by at least six orders of magnitude. Doped ''cis''-polyacetylene films usually have conductivities two or three times greater than doped ''trans''-polyacetylene even though the parent film has lower conductivity.<ref name="McDiarmiad synthetic metals"/>