Single Electron Transistor Based on Endohedral Metallofullerenes Me@C60 (Me = Li, Na, K)

In this work, within the framework of the density functional theory, the transport properties of a single-electron transistor (SET) based on metallofullerenes Me@C60 (Me ( Li, Na, K) were investigated by simulation. The optimization of Li@C60, Na@C60, K@C60 molecules was carried out using the Perdew-Burke-Ernzerhof (PBE) exchange-correlation functional and the generalized gradient approximation (GGA), which allows the most accurate description of such structures. Electrostatic difference potential, molecular energy spectrum, and total energy of a SET based on Me@C60 were calculated. It was found that a SET based on K@C60 is more stable than other considered SETs based on C60, Li@C60, Na@C60. The dependences of the total energy of molecules Me@C60 (Me ( Li, Na, K) on their total charge are determined, as well as the dependences of the total energy on the gate voltage Me@C60-SET. Due to the instability of the state of small molecules with additional electrons of more than two, during the simulation, the values of – 2, – 1, 0, 1, 2 were chosen as the total electric charges for each molecule. It is shown that the energy of a negatively charged metallofullerene under consideration is lower than that of a neutral one, and vice versa, the energy of a positively charged metallofullerene is greater than that of a neutral one. It was found that at negative transistor gate voltages, positive charge states (+ 1, + 2) are more stable compared to negative charge states (– 1, – 2) due to a shift in the HOMO (highest occupied molecular orbital) and LUMO (lowest unoccupied molecular orbital) with a change in gate voltage. The stability diagrams of SETs based on С60, Me@C60 were analyzed, and it was also shown that the area of the Coulomb diamond SET on the stability diagram depends on the radius of the encapsulated atom. The results obtained can be useful in the calculation of new types of SETs based on metallofullerenes.