Fabrication of conducting polymer modified CdS photoanodes for photoelectrochemical cell

Abstract

The present work focuses on the modification of a spray deposited nanostructured CdS thin films by thin layers of polyaniline (PANI) and polypyrrole (PPY) systems using electro-polymerization method. The deposition of the conducting polymer on the CdS/FTO (Fluorine doped tin oxide) film surface has been validated by X-ray diffraction, UV–Vis spectrometry and Fourier transform infrared spectrometry. As deposited PANI and PPY films exhibit a bandgap of 2.0 eV and 1.7 eV, respectively. Optimization of deposition parameters viz. applied field, concentration of monomer and pH of the precursor has been performed to obtain a uniform and an adherent coating over CdS surface. The absorption band-edge of CdS is not shifted due to its surface modification via. PANI and PPY. However coating of PANI enhanced the visible light absorption capacity of CdS. This additionally ensures that there exists a thin polymer coating over CdS. The photocurrent of CdS/PANI and CdS/PPY is found to be enhanced by 3.2 and 2.6 times as compared to the bare CdS. An improvement in the PEC performance could be attributed to the favorable band energetics between the conjugated polymers and CdS that effectively reduces the recombination process and thus enhances the charge transfer process.