Polyelectrolyte-Mediated Electrochemical Fabrication of a Polyacetylene p-n Junction

The diffusion of dopant counterions has made the formation of conjugated polymer p-n junctions challenging, We demonstrate polyelectrolyte mediated electrochemistry (PMEC) its a three-electrode technique for separately introducing n- and p-type regions in an ion-functionalized polyacetylene structure to form it p-n junction. PMEC uses a polyelectrolyte-based supporting electrolyte and ion-functionalized conjugated polymers to control the ions available for exchange between a solid sample and supporting electrolyte, and in this way, select for oxidative vs reductive electrochemical processes. A bilayer consisting of solid layers of anionically and cationically functionalized poly-acetylenes was driven first to -1.5 V vs SCE and then to 0.6 V vs SCE using tetrabutylammonium polystyrene sulfonate/acetonitrile as it supporting electrolyte. The negative potential step n-doped the entire Structure, and the positive potential step selectively p-doped the anionically functionalized layer to form a p-n junction its followed by spectroelectrochemistry and supported by current-voltage characterization. The polyacetylene p-n junctions were observed to exhibit diode behavior with ideality factors in the range of 3-3.5. Rectification ratios of greater than 500 at 1 V were achieved, and the junctions exhibited a small photovoltaic effect.