Publications by authors named "Calvin H Cheng"

The electrical behavior of the cationic, polyacetylene-based, conjugated ionomer, poly[(2-cyclooctatetraenylethyl)trimethylammonium trifluoromethanesulfonate], sandwiched between gold electrodes is reported. The steady-state current of this mixed ionically/electronically conducting system is assigned to be unipolar diffusive hole transport for voltages below approximately 1.4 V, giving way to bipolar migratory transport above approximately 1.

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Dopant counterion diffusion has made the conjugated polymer pn homojunction a challenging target for decades. We report the electrochemical fabrication of a polyacetylene pn homojunction based on internally compensated forms where the dopant counterions are covalently bound to the polymer backbone. After drying under vacuum, the pn junction exhibits diode behavior with the ratio of the forward to reverse current at 2 V being 7.

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Unidirectional electronic current is reported for a device based on the interface between an anionically functionalized and a cationically functionalized polyacetylene. The unidirectional current in this mixed ionically/electronically conducting system is electronic but is regulated by asymmetry in the ionic processes.

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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.

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