Orientation-Controlled (h0l) PbI₂ Crystallites Using a Novel Pb–Precursor for Facile and Quick Sequential MAPbI₃ Perovskite Deposition

Abstract

Organic−inorganic hybrid lead halide perovskites have shown significant progress in the last few years having achieved efficiencies over 25% at the lab scale. The sequential deposition technique has provided a robust approach in the perovskite film fabrication. However, obtaining a reproducible and quality perovskite film has always been challenging because of the highly crystalline and ordered (001) oriented underlying PbI 2 film. Here, we report a simple solution approach to fabricate a PbI 2 residue-free, superior grade perovskite film by using a compositional engineered PbI 2 −precursor solution. We demonstrate that the Pb−precursor film crystallized into a R-centered Hexagonal metric lattice with (h0l), (hk0), and (00l) orientations provides a more efficient and quicker conversion into perovskites compared to conventional (001) oriented 2H-PbI 2 . A porous and multi-oriented PbI 2 film is prepared by rationally incorporating a volumetric fraction of Pb(Ac) 2 •3H 2 O in the typical PbI 2 /dimethylformamide precursor solution, which significantly improves the surface features of PbI 2 as well as the structural properties. As a result, a compact, smooth, and large grain perovskite can be obtained by accomplishing a full conversion with comparatively much less reaction time. Furthermore, a comprehensive mechanism of structural modification of PbI 2 and the role of its orientation in ameliorating the reaction kinetics has been demonstrated.

PbI2 Nanocrystal Growth by Atomic Layer Deposition from Pb(tmhd)2 and HI

“…To get additional information about preferential orientation, we looked at the two-dimensional (2D) GIWAXS images in Figure B,C. For the 162-cycle deposition, the smaller peaks fade, and the PbI 2 nanocrystals show less diffraction signal for 001 when compared to the 81-cycle deposition, which may help result in greater ease-of-reaction in forming perovskite with exposure to MAI. , …”

“…For the 162-cycle deposition, the smaller peaks fade, and the PbI 2 nanocrystals show less diffraction signal for 001 when compared to the 81-cycle deposition, which may help result in greater ease-of-reaction in forming perovskite with exposure to MAI. 45,46 Chemical Composition. XPS was used to analyze the chemical composition at the surface of the deposited PbI 2 nanocrystals.…”

PbI2 nanocrystal growth by atomic layer deposition of Pb(tmhd)2 and HI

“…Further, to get additional information about preferential orientation, we looked at the 2D GIWAXS images in Figure 1b. For the 162-cycle deposition, the smaller peaks fade and the PbI2 nanocrystals show less diffraction signal for 001 when compared to the 81-cycle deposition, which may help result in greater ease-of-reaction with MAI [35], [36].…”

Effects of Lead Iodide Crystallization on Photovoltaic Performance of Perovskite Solar Cells by the Vapor-Solid Reaction Method

“…Hybrid metal halide perovskite has become one of the most promising photovoltaic materials due to its excellent optical absorption coefficient, high carrier mobility, and adjustable band gap. − At present, the power conversion efficiency (PCE) of perovskite solar cells (PSCs) recorded by the National Renewable Energy Laboratory (NREL) has reached 25.7% . However, most studies on PSCs are based on the fabrication of small-area devices with one-step or sequential two-step solution-processed methods. − In order to obtain high-quality perovskite films, efforts have been made to surface modification strategies, such as solvent engineering, anti-solvent-assisted crystallization, and vapor-assisted nucleation. − These methods require the use of toxic organic solvents such as chlorobenzene (CB), dimethylformamide (DMF), and dimethyl sulfoxide (DMSO), , which raise the risks of environment and health in mass production. Therefore, it is worth exploring the method of developing simple, non-toxic solvent, and easy-to-prepare efficient large-area PSCs.…”