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Type: 
Journal
Description: 
Halide perovskites containing a mixture of formamidinium (FA+), methylammonium (MA+) and cesium (Cs+) cations are the actual standard for obtaining record-efficiency perovskite solar cells. Although the compositional tuning that brings to optimal performance of the devices has been largely established, little is understood on the role of even small quantities of MA+ or Cs+ in stabilizing the black phase of FAPbI3 while boosting its photovoltaic yield. In this paper, we use Car-Parrinello molecular dynamics in large supercells containing different ratios of FA+ and either MA+ or Cs+, in order to study the structural and kinetic features of mixed perovskites at room temperature. Our analysis evidences that cation mixing relaxes the rotational disorder of FA+ molecules by preferentially aligning their axis towards cubic directions. The phenomenon stems from the introduction of additional local minima in the …
Publisher: 
American Chemical Society
Publication date: 
20 Jan 2020
Authors: 

Giuseppe Fisicaro, Antonino La Magna, Alessandra Alberti, Emanuele Smecca, Giovanni Mannino, Ioannis Deretzis

Biblio References: 
Origin: 
The Journal of Physical Chemistry Letters