We report on the electron trapping mechanism in a multi-level organic field effect transistor (OFET) memory using Lithium-ion-encapsulated fullerene (Li+@C60) as the floating gate. Based on the estimation of trapped electron number per each Li+@C60 molecule when a programming voltage was applied, the active domain of the floating gate was determined to be the surface of the Li+@C60 domain. An analysis of the cyclic voltammetry indicated that each Li+@C60 molecule can trap electrons at the trapping energy level of and eV. The number of trapped electron was confirmed by the ultraviolet-visible spectroscopy (UV-Vis). | Electron trapping mechanism in a multi-level organic fet memory using lithium-ionencapsulated fullerene as the floating gate