ISSN 1017-2548(Print)
ISSN 2234-8530(Online)
Volume 37, Number 7
JKCSEZ 37(7)
February 20, 1993 

Monolayers of pure surfactant squaraine, DSSQ(4-distearyl amino phenyl-4'-dimethylaminophenylsquaraine), were deposited on SnO2 electrodes by the Langmuir-Blodgett film technique. The DSSQ film exhibits λmax at ∼530 nm. The absorption is significantly red-shifted from the solution of DSSQ (633 nm in chloroform), suggesting that the squaraine chromophores form aggregates in the LB film. The photogeneration of the squaraine aggregates is studied by measuring the photocurrents in photoelectrochemical cells consisting of the squaraine of the aggregates is found to parallel its absorption spectrum and quantum efficiency as high as 0.3% has been observed. While the photocurrent was attenuated exponentially when stearic acid layers (up to 8 layers) are inserted between the squaraine layer and the electrode, it is nearly extinguished when the squaraine layer is over-coated with 2 layers of stearic acid. A model for the observation is proposed and the roles of the electrolytes and oxygen on the photogeneration process will be discussed.