Research ArticleMATERIALS SCIENCE

Revealing the detailed path of sequential deposition for metal halide perovskite formation

See allHide authors and affiliations

Science Advances  02 Feb 2018:
Vol. 4, no. 2, e1701402
DOI: 10.1126/sciadv.1701402

You are currently viewing the abstract.

View Full Text

Abstract

Sequential deposition has been extensively used for the fabrication of perovskite solar cells. Nevertheless, fundamental aspects of the kinetics of methylammonium lead iodide perovskite formation remain obscure. We scrutinize the individual stages of the reaction and investigate the crystallization of the lead iodide film, which occurs before the intercalation of methylammonium iodide commences. Our study identifies the presence of mixed crystalline aggregates composed of perovskite and lead iodide during intercalation and structural reorganization. Furthermore, Ostwald ripening occurs in the film for reaction times beyond the point of conversion to perovskite. Using cross-sectional confocal laser scanning microscopy for the first time, we reveal that lead iodide in the over-layer and at the bottom of the mesoporous layer converts first. We identify unreacted lead iodide trapped in the mesoporous layer for samples of complete conversion. We acquire kinetic data by varying different parameters and find that the Avrami models best represent them. The model facilitates the rapid estimation of the reaction time for complete conversion for a variety of reaction conditions, thereby ascertaining a major factor previously determined by extensive experimentation. This comprehensive picture of the sequential deposition is essential for control over the perovskite film quality, which determines solar cell efficiency. Our results provide key insights to realize high-quality perovskite films for optoelectronic applications.

This is an open-access article distributed under the terms of the Creative Commons Attribution-NonCommercial license, which permits use, distribution, and reproduction in any medium, so long as the resultant use is not for commercial advantage and provided the original work is properly cited.

View Full Text