Electronic, photocatalytic and piezoelectric properties of n=3 Dion-Jacobson-type perovskite monolayer A′[A2B3O10]

On the basis of first-principles calculations, we have studied the electronic, photocatalytic and piezoelectric properties of Dion-Jacobson-type (DJ) perovskite monolayer A'[A(2)B(3)O(10)] (A' = Li, Na, K, Rb, Cs; A = Ca, Sr, Ba; B = Nb, Ta). Our results show that A'[A(2)B(3)O(10)] monolayers have low formation energies similar to that of MoS2 and InSe nanosheets, which means they can be mechanically extracted from their layered bulk counterparts. A'[A 2B3O10] monolayers are all indirect band gap semiconductors (3.30-4.22 eV) whose valence band maximum (VBM) is determined by O atom and conduction band minimum (CBM) is determined by Nb/Ta atom. Importantly, the electron-hole pairs in A'[A(2)B(3)O(10)] monolayers are distributed in different spatial regions. The proper CBM and VBM positions in comparison with the redox potentials of water imply that they can be used as photocatalysts for overall water splitting. The out-of-plane piezoelectric coefficient e(zz) is found to be 4.76-5.08 C m(-2), which is much larger than that of the commonly used piezoelectric materials. We believe the DJ perovskite monolayers, with unique electronic, photocatalytic and piezoelectric properties, are very good candidate of electronic and water splitting devices.