Charge states of lanthanide double-decker phthalocyanines complexes significantly influence their geometrical structures and magnetic properties. In this study, the charge states of single DyPc2 molecules on an ultrathin CuO film were detected by scanning tunneling microscopy and spectroscopy in magnetic fields. Four types of adsorptions of DyPc2 molecules on CuO were experimentally observed. Without applying voltages, two of them were positively charged with the other two at the neutral state. By controlling the sample bias, two types of neutral molecules can be switched to the positively and negatively charged states, respectively. This manipulation was not realized for the DyPc2 cations. A way to precisely detect the molecular charge states with and without current is beneficial for the development of molecular electronics.
Keywords: CuO; DyPc2; charge state; scanning tunneling microscopy; scanning tunneling spectroscopy.