Attaching electro-active species at the surface of semiconductor (SC) electrodes permanently affects their photo-electrochemical (PEC) properties.  Depending on the charge of the electro-active species, the flat band potential may be shifted up (more negative) or down (more positive).  The shift value depends on attached ion charge density at the surface. Up to 300 mV shifting has been achieved here. Moreover, the electro-active ions function as charge transfer catalyst across the solid/liquid junction. This increases the charge (holes or electrons, depending on type of SC) transfer rate between the SC electrode and the redox couple. The SC electrode can thus be stabilized to photo-degradation. All such advantages can be gained by attaching the proper electro-active materials to the proper SC electrode.  The attachment can be performed either by chemical linkage or by embedding the electro-active material inside a polymer matrix.  The new technique has been successfully applied to monolithic and to polycrystalline SC electrode systems. Monolithic n-GaAs electrode showed up to eight fold enhancement in PEC conversion efficiency. Polycrystalline film electrodes, involving nano-particles of semiconductors (CuS, CuSe, CdSe, CdTe, and others), are globally known to be unstable with low conversion efficiency (~1.0% or less) under PEC conditions.  Modified film electrodes have been modified by the new method.  Conversion efficiency values of 4.4, 8.0, 15.0% and 18.0% have been observed from CdSe, CdTe, CuS and CuSe film electrodes, respectively. Such values have not been reported for pristine metal chalcogenide film electrodes before. This presentation will show a critical survey of our results observed throughout the last 15 years, as compared to other literature. The new model proposed for the efficiency and stability enhancement will also be rigorously presented.  Future prospects of this work will also be discussed.

Conference Title

THIRD INTERNATIONAL SYMPOSIUM ON DIELECTRIC MATERIALS AND APPLICATIONS - ISYDMA'2018, April 17-20, 2018

Conference Country

Palestine

Conference Date

April 17, 2018 - April 20, 2018

Conference Sponsor

University Sultan Mulai Suleiman

Additional Info

Conference Website