Synthesis, characterization and photoelectrochemical properties of poly(3,4-dioctyloxythiophene)-CdS hybrid electrodes

CdS-poly(3,4-dioctyloxythiophene) (CdS-PDOT) hybrid electrode has been prepared by electrosynthesis of PDOT on Au substrate followed by electrodeposition of Cd and its chemical transformation into CdS. The polymer and semiconductor obtained by this method form hemispherical structures dispersed on the substrate. The synthesized composites were characterized by UV-vis absorption spectra and energy dispersive X-ray spectra (EDS). The AFM images of the electrodes covered with different amounts of each component were correlated with photoactivity of the hybrid electrodes. Photoresponses of Au/PDOT-CdS electrodes under illumination in aqueous solution of Na2S were also compared with those of CdS without polymer. Enhancement of the photocurrent achieved for some polymer-to-semiconductor ratio is discussed in terms of the hybrid electrode morphology and hole-mediating properties of PDOT. The power conversion efficiency of the device based on CdS-PDOT hybrid electrode was determined from photocurrent-potential behavior of two electrode system, Au/CdS-PDOT/0.1 M Na2S/Pt with a variable resistance in series in the external circuit.