The crucial role of density functional nonlocality and on-axis CH 3 NH 3 rotation induced I 2 formation in hybrid organic-inorganic CH 3 NH 3 PbI 3 cubic perovskite

• Published in: Scientific reports Vol. 8; no. 1; p. 13161
• Main Authors: Klinkla, Rakchat, Sakulsupich, Vichawan, Pakornchote, Teerachote, Pinsook, Udomsilp, Bovornratanaraks, Thiti
• Format: Journal Article
• Language: English
• Published: England 03.09.2018
• ISSN: 2045-2322

Effects of electronic nonlocality in density functional theory study of structural and energetic properties of a pseudocubic CH NH PbI are investigated by considering coherent rotation around C-N axis of a CH NH cation. A number of truly non-local and semi-local exchange correlation density functionals are examined by comparing calculated structural parameters with experimental results. The vdW-DF-cx which takes into account the non-local van der Waals correlation and consistent exchange shows the best overall performance for density functional theory study of this system. Remarkable distinctions between results from vdW-DF-cx and those from PBEsol exchange correlation functionals are observed and indicate the need of including the non-local interaction in the study of this system, especially its dynamical properties. The obtained rotational barriers are 18.56 meV/formula and 27.71 meV/formula which correspond to rotational frequencies of 3.71 THz and 2.60 THz for vdW-DF-cx and PBEsol calculations, respectively. Interestingly, the maximally localised Wannier function analysis shows the hydrogen bonding assisted covalent character of two iodide anions at a moderate rotational angle which can lead to I formation and then material degradation.