Figure 4.

(a–c) Planar and side views of the slabs optimized at 0 K. Cs⁺ and primary (methylammonium) and secondary (dietyhlammonium) amine passivated structures are given from top to bottom. Panels a and b show the lattice vectors in reciprocal space that are replicated periodically, while panel c shows the lattice vector in the finite direction. On the right of each structure is their corresponding pair radial distribution functions for the Pb–Pb and Cs–Cs (or N–N) atomic distances, calculated by ab initio MD simulations at the DFT or PBE level of theory with the NPT ensemble (T = 300 K, P = 1 atm). (d, e) Side and planar view of the binding of primary (top) and secondary amines (bottom). In the case of secondary amines, the anchoring groups are closer to each other than in primary amines, indicating a larger steric hindrance.