Unraveling the Effect of Crystal Structure on Degradation of Methylammonium Lead Halide Perovskite

Abstract

Despite the remarkable efficiencies of perovskite solar cells, moisture instability has still been the major constraint in the technology deployment. Although, some research groups have discussed the possible mechanisms involved in the perovskite degradation, no broader understanding has been developed so far. Here, we demonstrate that the crystal orientation of perovskite film plays a major role in its degradation. We observed that the films fabricated via different routes led to different degradation behaviors and unraveled that diversity in the degradation rate arises due to the difference in crystallographic characteristics of the films. Using optical and electrical measurements, we show that the film prepared via a single-step (lead chloride precursor based) route undergoes a much faster degradation rate as compared with films prepared using single step (acetate precursor based) and two-step (or sequential deposition) routes. Although the resulting film is methylammonium lead iodide (MAPbI 3 ) regardless of processing via different routes, their respective crystal orientation is different. In this manuscript, we correlate crystal orientation of MAPbI 3 with their degradation pattern. Our studies also suggest a possible way to make stable perovskite film.

Molecular‐Level Insight into Correlation between Surface Defects and Stability of Methylammonium Lead Halide Perovskite Under Controlled Humidity

“…This relatively counter‐intuitive result has also been noted in a few cases in the literature. [ 15,24b,29 ] This phenomenon stems from the creation of additional radiative recombination pathways, as discussed below. The PL maximum red‐shifts from 780 to 784 nm for MAPbI 3 and from 771 to 785 nm for MAPbI 3 with PbI 2 excess.…”

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

“…All the films exhibit the tetragonal crystal systems with diffraction at 2theta values of around 14.47, 24.87, 28.74, 32.18, and 41.04° corresponding to plane orientations of (110), (211), (220), (114), and (224). 41 In the diffraction pattern of the perovskite from pure PbI 2 , we can see the strong reflection at around 12.85° and 38.98° and can be assigned to unreacted PbI 2 . 9 The addition of Pb(Ac) 2 in the pristine PbI 2 solution helps in improved conversion of the underlying layer into the perovskite and substantially reduces the intensity of the PbI 2 signature diffraction peak.…”

Morphology and Crystallinity Amelioration of MAPbI3 Perovskite in Virtue of PbI2 Thermal Absorption Drifted Performance Enhancement in Planer n–i–p Solar Cells

“…All the perovskite samples possess tetragonal crystal structure with diffraction peaks at 14.02, 19.90, 24.42, 28.34, 31.80, and 40.58 corresponding to (110), (112), (211), (220), (114), and (224) plane orientations. [ 21 ] We observed that the diffraction counts increase with the annealing temperature of the lead iodide film (Figure S3a,e, Supporting Information). The intensified values of the diffraction peaks show improvement in the crystallinity of the perovskite film.…”

“…[ 17,18 ] Alternatively, the two‐step deposition method provides the advantage of control over the perovskite film morphology due to the slow crystallization process. [ 19,20 ] In addition, this route also features other advantages such as 1) robust fabrication process due to implication of inorganic layer, 2) comparatively more robust to moisture during fabrication and in outdoor, [ 21 ] 3) flexibility to adapt the fabrication method for each layer, and 4) flexibility to optimize each layer separately. [ 22,23 ] The quality of the perovskite fabricated from the sequential deposition method greatly depends on the underneath lead iodide layer and the method of conversion into perovskite.…”