Attaching electro-active species semiconductor (SC) electrode surfaces permanently affects their photo-electrochemical (PEC) properties. Depending on the electro-active species charge type and density at the surface, the flat-band potentials are shifted up or down. Up to 300 mV shifting is achieved here. The electro-active species catalyzes charge transfer across the solid/liquid junction. This increases the charge (holes or electrons depending on the type of the SC) transfer rate at the junction. Thus, the SC electrode can be stabilized to photo-degradation. All such advantages are achieved by attaching proper electro-active materials to the SC electrode. The attachment can be performed either by chemical linkage or by embedding the catalyst inside a polymer matrix. This is successful in monolithic and polycrystalline SC electrode systems. Monolithic n-GaAs electrode showed eight-fold enhancement in photoelectrochemical efficiency. Polycrystalline film electrodes of semiconductors (CuS, CuSe, CdSe, CdTe, and others), are normally unstable with low PEC efficiency (~1.0% or less). With the new method, efficiency values of 4.4, 8.0, 15.0% and 18.0% are observed from CdSe, CdTe, CuS and CuSe film electrodes, respectively. The CuS and CuSe film efficiencies are beyond values expected by the US DOE for the year 2020, and 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.
Key Words: Semiconductors; Thin Film Electrodes; Conversion Efficiency; Stability; Charge Transfer Catalysis.