Elucidating the Methylammonium (MA) Conformation in MAPbBr3 Perovskite with Application in Solar Cells

TL;DR

This study investigates the crystal structure and methylammonium conformation in MAPbBr3 perovskite, revealing structural details across phase transitions and demonstrating its potential in optoelectronic applications like solar cells.

Contribution

It provides a detailed structural analysis of MAPbBr3, combining neutron and synchrotron XRD data to understand phase transitions and MA conformation, which was previously not well characterized.

Findings

Structural features of MAPbBr3 across phase transitions elucidated.

Neutron and synchrotron XRD reveal subtle symmetry changes.

Photocurrent measurements demonstrate optoelectronic potential.

Abstract

Hybrid organic-inorganic perovskites, MAPbX3 (X= halogen), containing methylammonium (MA: CH3-NH3+) in the large voids conformed by the PbX6 octahedral network, are the active absorption materials in the new generation of solar cells. CH3NH3PbBr3 is a promising alternative with a large band-gap that gives rise to a high open circuit voltage. A deep knowledge of the crystal structure and, in particular, the MA conformation inside the perovskite cage across the phase transitions undergone below room temperature, seems essential to establish structure-property correlations that may drive to further improvements. The presence of protons requires the use of neutrons, combined with synchrotron XRD data that help to depict subtle symmetry changes undergone upon cooling. We present a consistent picture of the structural features of this fascinating material, in complement with photocurrent measurements from a photodetector device, demonstrating the potential of MAPbBr3 in optoelectronics.