Modulation of strain, electric field and organic cation rotation on the band gap and electronic structures of organic-inorganic hybrid perovskite CH3NH3PbI3

Regulating structural stability and photoelectrical properties of FAPbI3via formamidine cation orientation

“…2), it can be seen that the minimum energy is located at 45° and the maximum energy is reached at 180°, which originates from the interaction between the anions and cations. 29 In order to reveal the atomic structural characteristics, we selected 45° and 180° angles along the three different in-plane directions and conducted the atomic structure diagram as shown in Fig. 3.…”

“…[26][27][28] Therefore, we will rigorously unify the description of the FAPbI 3 as the pseudo-cubic in the following description. Based on the cation orientations in the previous studies, [28][29][30] 31 The Perdew-Burke-Ernzerh formulation of generalized gradient approximation (PBE+GGA) was employed to account for the exchange-correlation function. 32 The van der Waals (vdW) correction of Grimme with zero-damping (DFT-D3) was used to consider the dispersion interactions.…”

“…26–28 Therefore, we will rigorously unify the description of the FAPbI 3 as the pseudo-cubic in the following description. Based on the cation orientations in the previous studies, 28–30 here, four representative orientations of FA + are introduced, namely [001], [010], [110] and [111] directions. The organic cation FA + is located in each plane and rotates one revolution relative to the normal of the crystal plane (with an interval of 45°) to obtain its configuration, and then relaxation calculations are performed.…”