Abstract
Thermal desorption of oxygen from the surface of β-copperphthalocyanine has been investigated in the temperature range of room temperature to 200°C by X-Ray Photoelectron Spectroscopy. The Ols peak due to adsorbed oxygen began to decrease at about 90°C and decreased further as the temperature increased. This direct observation of the thermal desorption supports the photocurrent-quenching model, in which the thermal quenching is caused by thermal desorption of ionosorbed oxygen in the form of O- 2 which has created an electrostatic field necessary for exciton dissociation into free electrons and holes.