Abstract: n-Si(111) surface tailed -C2H5, -C2H4COOH, -C2H2COOH were prepared by the reactions among Si–H to ethyl-Grignard, methyl acrylate and ethyl propionate, and the carboxyls were formed under the existence of trifluoroacetic acid. The composite n-Si(111) electrodes were obtained by depositing Pt nanodots and the photovoltaic characteristics for these electrodes were studied in I-/I3- redox electrolyte. The j-U (photo current density-potential) behaviors of photo-voltage and photocurrent densities to the electrodes under solar illumination varied regularly with groups of -C2H2COOH>-C2H4COOH>-H>-C2H5. The photo-voltage and photocurrent density of the electrode tailed -C2H2COOH were -0.641 V and 5.25 mA/cm2, respectively, more negative than those of the non-conjugated modification.

Key words: n-Si(111) wafer, Photo-voltage, Photocurrent density, Semiconductor electrode