Investigation of phase transition and the effect of stress on piezoelectric coefficients in three 2D structures of In2Se3

In this paper, we investigate the total and Gibbs free energies of the three phases of In2Se3 2D structures under stress, using the first-principles calculations. In addition, the phase transition between different phases under stress is examined. We observe two transitions between FE-ZB′ (α) and FE-WZ′ phases in the diagram of Gibbs free energy vs stress. The elastic properties, polarization and α−In2Se3 band structure has been also calculated. Besides, changes in bond length and band angles under stress are examined. The results of examining the α−In2Se3 band structure indicate that the bandgap is in the infrared range. Furthermore, we obtain the piezoelectric coefficients in terms of stress, and observe that they can increase up to about twice by changing stress. Our results show that peaks are not observed in the piezoelectric coefficient diagram in terms of stress at points where transitions occur. It is expected that the results could be guides to achieving large piezoelectric coefficients.