Work

From PbI2 to MAPbI3 through Layered Intermediates

Year: 2016

Type: article

Abstract: In the present work we describe the process of formation of methylammonium lead iodide perovskite (MAPbI 3 ) by reaction between [001] oriented PbI 2 thin films and MAI. The reaction leads to a rapid change in the optical properties with the formation of a brown phase having a large band in the visible range and a contribution in the near-UV range (375 nm). X-ray diffraction analyses indicate that the MAI + PbI 2 as-obtained material mainly consists of a highly oriented matrix of MAI that intermixes with the Pb–I precursor. A chemical exfoliation of the initial PbI 2 structure with the massive intercalation of the methylammonium iodide ions suitably describes the optical and structural findings. Short thermal treating (100 °C) of this as-obtained sample results in the formation of a second oriented intermediate phase, attributed to the presence of a low-dimensional perovskite structure. Such low-dimensional metastable phase is no longer visible by increasing the annealing time or the annealing temperature (150 °C), with the 3D MAPbI 3 tetragonal phase left in the XRD pattern.

Source: The Journal of Physical Chemistry C

DOI: 10.1021/acs.jpcc.6b03798