Abstract: The surface photovoltaic characteristic of copper tetrasulfonato- phthalocyanine (CuTsPc) in water vapor was studied by surface photovoltage spectroscopy (SPS). It was found that the adsorption of water vapor caused some marvelous changes of the photovoltaic response, that is, the SPS signal diminished rapidly and even reversed; the bands were widened and displayed a bathochromic shift. The dependence of surface photovoltage on the vapor pressure indicates that the reversed signal reaches to a maximum when the vapor pressure is 4.7×10² Pa. The time response velocity, reversibility, selectivity and reproducibili-ty were examined as well. All results obtained show that CuTsPc is of great significance in the manufacture of moisture sensitive devices. In addition, the mechanism of moisture sensitivity is discussed.

Key words: Moisture sensitive material, Copper tetrasulfonato-phthalocyanine, Surface pho-tovoltage spectroscopy