Nanoscale organized assembly of nanoparticulate TiO2-stearate monolayers through the Langmuir-Blodgett method

Nanoparticulate titanium dioxide-stearate (TiO2-St) monolayer was directly obtained using TiO2 hydrosol as the subphase. The atomic force microscopy images of monolayer, show that the higher coverage were obtained through deposition on the hydrophilic Si(100) surface rather than the hydrophobic Si(100) surface. From the surface photovoltage spectra of TiO2-St monolayer, it can be followed that the photovoltage response of the n-type silicones increased by a factor of 25, and 5 times after a monolayer of TiO2-St Langmuir-Blodgett (LB) films was transferred onto hydrophobic and hydrophilic Si surface, respectively. On the contrary, the photovoltage response value is reduced by similar to 40 and 5 times by the deposition of the LB monolayer in the case of the hydrophobic and hydrophilic p-type Si surface, respectively. It is considered that the enhancement of the photovoltage response may be due to the ordered electrostatic potential orientation of the Si(100)/TiO2-St/ITO heterostructures. (C) 1997 American Vacuum Society. [S0734-211X(97)00705-4].