Semiconductor Electrodes XLII . Evidence for Fermi Level Pinning from Shifts in the Flatband Potential of p‐Type Silicon in Acetonitrile Solutions with Different Redox Couples

The flatband potential, , of p‐Si electrodes in acetonitrile solutions containing various redox couples was determined by measurement of the cell impedance. was found to depend strongly on the redox potential of the solution, indicating the occurrence of Fermi level pinning. The shift of did not depend upon the nature (cationic or anionic) of the redox couples; thus it cannot be attributed to specific adsorption. The shift in was also found with redox couples (such as oxazine and benzoquinone) which have energy levels located below the middle of the gap, implying that inversion does not occur in these cases.