Three-levels conductance switching in an organic memory cell

A solid-state memory based on a hindered phenol substituted bithiophene is reported, showing conductance switching behaviour between three discrete states among which it is possible to cycle repeatedly on the basis of three characteristic threshold voltages. The experimental measurements show that the addressing of the three states is independent of the programming time, that the retention time for each state is longer than 15 h and that the devices endure current-voltage cycles well in excess of 50. Considerations based on density functional theory calculations are made to provide hints on the mechanism behind this memory effect.