Electrochemical Characterization of Polyacetylene Ionomers and Polyelectrolyte-Mediated Electrochemistry toward Interfaces between Dissimilarly Doped Conjugated Polymers

Abstract

The electrochemical characterization of thin films of the ionically functionalized polyacetylene analogues poly(tetramethylammonium 2-cyclooctatetraenylethanesulfonate) (P(A)) and poly[(2-cyclooctatetraenylethyl)trimethylammonium trifluoromethanesulfonate] (P(C)) is reported along with an electrochemical approach to the fabrication of interfaces between dissimilarly doped conjugated polymers. Such interfaces are of interest because of the central role analogous interfaces based on silicon play in conventional microelectronics. The cationically functionalized P(C) can be both oxidatively (p-type) and reductively (n-type) doped to a conductive state, whereas the anionically functionalized P(A) can only be p-type doped. The voltammetry of P(C) displays relatively sharp waves with minimal history or relaxation effects. In contrast, the voltammetry of P(A) exhibits broader doping waves and a dependence on electrochemical history. The apparent formal potentials reported in 0.075 M Me4NBF4/CH3CN were -1.04 V versus SCE for the n-doping of P(C) and 0.40 and 0.30 V versus SCE for the p-doping of P(C) and P(A), respectively. These values depend on electrolyte concentration consistent with a Donnan potential due to the selective partitioning of ions between the electrolyte and polymer. Electrochemical quartz crystal microbalance data demonstrate that the p-type doping of P(A) and the n-type doping of P(C) proceed with the loss of ions from the polymer film and the formation of the internally compensated state. Voltammetry in tetrabutylammonium poly(styrenesulfonate)/CH3CN supporting electrolyte is also reported. It is demonstrated how a polyanion supporting electrolyte in concert with a conjugated ionomer can be used to control redox chemistry by governing the sign of ions available for charge compensation. In particular, we demonstrate the self-limiting oxidation of P(A) to inhibit deleterious overoxidation and prepare the precisely internally compensated state; the selective oxidation of P(A) over P(C), despite their similar apparent formal potentials; and the inhibition of the reoxidation of the n-doped form of P(C). The use of such polyelectrolyte-mediated electrochemistry in the fabrication of interfaces between dissimilarly doped conjugated polymers is discussed.

Gate electrode processes in an electrolyte-gated transistor: Non-Faradaically versus Faradaically coupled conductivity modulation of a polyacetylene ionomer

“…Here, conductivity, which is typically associated with transport via drift, is used somewhat loosely. 9 The data in Fig. 8 The relation of the conductivity to the doping level is often presented in terms of the sourcedrain current I SD in response to a small source drain voltage V SD versus E AM , which is determined by the doping level of the active material.…”

Homojunction Solar Cells

“…While the Si cells continued to develop, efforts began on p-n homojunction cells based on other singlecrystal semiconductor materials, such as GaAs. 9 The consensus is that they may not be possible [10][11][12] due to (1) the inability of built-in cell fields to dissociate excitons [13][14][15][16] and consequently due to (2) the need for a semiconductor heterojunction or metalsemiconductor interface for exciton dissociation and charge separation. 5 The wide gap (p)Ga y Al 1y As layer in this structure reduced photogeneration near the front surface and served as a selective ohmic contact.…”

Disubstituted Polyacetylenes Containing Photopolymerizable Vinyl Groups and Polar Ester Functionality: Polymer Synthesis, Aggregation-Enhanced Emission, and Fluorescent Pattern Formation

“…5 A large number of monosubstituted PAs bearing various pendant groups have been designed and synthesized. [4][5][6][7][8][9][10][11][12][13][14][15][16][17] When appropriate pendants are introduced, the polymers can be endowed with such functional properties as mesomorphism, 4,6 luminescence, 5,7-9 photoconductivity, 10 redox activity, 11,12 gas permeability, 13 chain helicity, 14-16 biocompatibility, and cytophilicity. 17 Despite these attractive functionalities, monosubstituted PAs still suffer from the instability problem: many of them degrade during storage, especially in the solution state.…”