Change in ionization potential of magnesium tin oxide films before and after photochromism

Magnesium-tin oxide (MTO) became a cell storage material after strong UV irradiation, and the appearance of the photochromic phenomenon was the sign of initiation of such a function. This phenomenon is not an independent behavior occurring in magnesium-tin oxide films, but we found that the phenomenon occurred in the interface between the MTO layer and indium tin oxide layer prepared under the MTO layer. To clarify this phenomenon, analysis of the MTO layer is the key issue and investigation under the environmental condition is required. The photochromic color change does not reproduce by excess heating treatment. In this paper, we focused on the change in the ionization potential of the MTO film before/after the reversible color change and irreversible erase, and to achieve this experiment, we constructed a novel photoelectron yield spectrometer and measured the ionization potential of a magnesium tin oxide film.