Sensitized Photocurrent through a Semiconductor Electrode by Consecutive Energy and Electron Transfer in Dye Monolayers

Electron injection from photoexcited cyanine dyes into the conduction band of a thin film semiconductor (indiumoxide) is investigated in an electrochemical cell. The sensitizing dyes are incorporated into tenside monolayers covering the electrode. Separation of the chromophores from the electrode by two tenside layers suppresses sensitized photocurrent. Insertion of an appropriate second dye at the semiconductor surface recovers the sensitizing yield of the distant dye. The distant dye absorbs light, transfers energy to the second dye at the semiconductor surface which transfers an electron into the electrode. The processes in this concerted energy‐electron‐transfer system are characterized by simultaneous measurement of photocurrent and fluorescence emission.