Transformation from crystalline precursor to perovskite in PbCl<sub>2</sub>-derived MAPbI<sub>3</sub>.
basic_science · Level V
Where this comes from
- Record sourced from PubMed, PMID 30150720.
- Also identified by DOI 10.1038/s41467-018-05937-4 and PMC identifier 6110813.
- Licence recorded as CC BY.
- The licence permits redistribution, so the abstract is shown in full and the full text is available from the publisher.
Abstract
Understanding the formation chemistry of metal halide perovskites is key to optimizing processing conditions and realizing enhanced optoelectronic properties. Here, we reveal the structure of the crystalline precursor in the formation of methylammonium lead iodide (MAPbI<sub>3</sub>) from the single-step deposition of lead chloride and three equivalents of methylammonium iodide (PbCl<sub>2</sub> + 3MAI) (MA = CH<sub>3</sub>NH<sub>3</sub>). The as-spun film consists of crystalline MA<sub>2</sub>PbI<sub>3</sub>Cl, which is composed of one-dimensional chains of lead halide octahedra, coexisting with disordered MACl. We show that the transformation of precursor into perovskite is not favored in the presence of MACl, and thus the gradual evaporation of MACl acts as a self-regulating mechanism to slow the conversion. We propose the stable precursor phase enables dense film coverage and the slow transformation may lead to improved crystal quality. This enhanced chemical understanding is paramount for the rational control of film deposition and the fabrication of superior optoelectronic devices.