Issue 39, 2016

A close examination of the structure and dynamics of HC(NH2)2PbI3 by MD simulations and group theory

Abstract

The formamidinium lead iodide hybrid perovskite is studied using first principles molecular dynamics simulations and further analyzed using group theory. The simulations are performed on large supercells containing 768 atoms under isothermal and fully anisotropic isobaric conditions. Two trajectories, one at 300 K and another at 450 K, were extended for over 50 ps in order to perform a detailed assessment of the rotational dynamics of organic cations. The characteristic rotations of the cation are analyzed by defining two rotation axes. It is found that the formamidinium molecules rotate preferentially around the direction parallel to the line connecting the two nitrogen atoms. The rotational dynamics shows some characteristics already observed in methylammonium lead iodide, like the heterogeneous dynamics at room temperature that disappears at 450 K. The orientational probability of the molecules is explored in terms of an expansion in cubic harmonics up to the 12th order. It reveals a strong directionality at room temperature that relaxes when increasing the temperature. These findings are further rationalized using Landau and group theories suggesting a mixed displacive/order–disorder structural instability at lower temperatures.

Graphical abstract: A close examination of the structure and dynamics of HC(NH2)2PbI3 by MD simulations and group theory

Supplementary files

Article information

Article type
Paper
Submitted
30 abr. 2016
Accepted
22 jun. 2016
First published
22 jun. 2016

Phys. Chem. Chem. Phys., 2016,18, 27109-27118

A close examination of the structure and dynamics of HC(NH2)2PbI3 by MD simulations and group theory

M. A. Carignano, Y. Saeed, S. A. Aravindh, I. S. Roqan, J. Even and C. Katan, Phys. Chem. Chem. Phys., 2016, 18, 27109 DOI: 10.1039/C6CP02917E

To request permission to reproduce material from this article, please go to the Copyright Clearance Center request page.

If you are an author contributing to an RSC publication, you do not need to request permission provided correct acknowledgement is given.

If you are the author of this article, you do not need to request permission to reproduce figures and diagrams provided correct acknowledgement is given. If you want to reproduce the whole article in a third-party publication (excluding your thesis/dissertation for which permission is not required) please go to the Copyright Clearance Center request page.

Read more about how to correctly acknowledge RSC content.

Social activity

Spotlight

Advertisements