PHOTOELECTRIC SIGNALS OF CHLOROPHYLL-A LANGMUIR-BLODGETT-FILMS

Photoelectric cells of ITO/insulator/chlorophyll a/insulator/InGa liqu id metal, containing 1, 2, 4 or 10 LB monolayers of chlorophyll a as p hotoactive layers and 9-10 stearyl amine films as insulator layers hav e been studied by measuring the transient photovoltage and transient p hotocurrent responses in the micro- to millisecond and second time dom ains, respectively, The signals were created either by a laser pulse o r by step-wise excitation. The cells exhibited light-induced charge tr ansport inside the chlorophyll layers in the direction from the InGa t o the ITO electrode. The charge movement is explained by an internal e lectric field due to the metal surface potentials, and was confirmed b y measurements for when an external voltage was applied. A model based on a single-step light-induced charge shift is discussed, and the qua ntum yield for the light-induced charge generation has been estimated to be close to unity.