1. A memory cell, comprising: a first ferroelectric layer between a first electrode and a second electrode; and a second ferroelectric layer between the second electrode and a third electrode, wherein at least two of the electrodes have different work functions which are different by at least 0.4 V, wherein: the first ferroelectric layer and the second ferroelectric layer are polarizable to provide at least three non-volatile states for the memory cell including a positive polarized state, a neutral polarized state and a negative polarized state; in the positive polarized state of the memory cell, the first and second ferroelectric layers are in a positive polarized state; in the neutral polarized state of the memory cell, the first ferroelectric layer is in the positive polarized state and the second ferroelectric layer is in the negative polarized state; and in the negative polarized state of the memory cell, the first and second ferroelectric layers are in the negative polarized state.