Understanding Moisture Stability of Crystalline and Defect Passivated Methylammonium Lead Iodide Perovskites
Parth Raval a, Mohammad Ali Akhavan Kazemi b, Frédéric Sauvage b, Olivier Lafon a, Laurent Delevoye a, G N Manjunatha Reddy a
a Univ. Lille, CNRS, Centrale Lille Institut, Univ. Artois, UMR 8181−UCCS− Unité de Catalyse et Chimie du Solide,59000, Lille, France
b Laboratoire de Réactivité et Chimie des Solides (LRCS), UMR CNRS 7314 - Institut de Chimie de Picardie FR 3085, Université de Picardie Jules Verne, 33 rue Saint Leu, FR-80039 Amiens Cedex, France
Proceedings of Atomic-level characterization of hybrid perovskites (HPATOM)
Online, Spain, 2021 January 26th - 28th
Organizers: Dominik Kubicki and Amita Ummadisingu
Poster, Parth Raval, 028
Publication date: 14th January 2021
ePoster: 

Hybrid halide perovskites have drawn significant attention due to their outstanding photovoltaic capabilities. However, these materials exhibit poor environmental stability with respect to moisture, light and temperature, which limits the long-term performance in solar cells. Here, we present the multi-technique approach that combines solid-sate NMR spectroscopy, X-ray diffraction and electron microscopy to gain atomic-level insights into the moisture-induced degradation pathways in crystalline 3D methylammonium lead iodide (MAPbI3) perovskites. The influence of moisture (40% and 85% relative humidity) on the MAPbI3 is examined over a year using ex-situ ssNMR measurements. In particular, 1D 1H and 2D 1H-1H correlation experiments allow the changes in the local structures of organic cations to be measured and distinguished in fresh and moisture aged materials. These results are further corroborated with X-ray diffraction, in operando liquid cell transmission electron microscopy measurements and analyses. By comparison, defect passivated MAPbI3 by dilute concentrations of tertiary propylamine cation (TPA+, 2-4mol%) exhibits enhanced moisture stability. As a result, defect passivated perovskite devices with only 2 mol% of TPA+ achieve power conversion efficiencies over 18.5% and retain more than 85% of their initial performances for over 1500 h under ambient conditions (55±5% RH).1 This work highlights the importance of atomic-level understanding of chemical degradation pathways and the defect passivation routes to achieve stable and efficient hybrid perovskites for photovoltaic applications.2

References:

(1)      Krishna, A.; Akhavan Kazemi, M. A.; Sliwa, M.; Reddy, G. N. M.; Delevoye, L.; Lafon, O.; Felten, A.; Do, M. T.; Gottis, S.; Sauvage, F. Defect Passivation via the Incorporation of Tetrapropylammonium Cation Leading to Stability Enhancement in Lead Halide Perovskite. Adv. Funct. Mater. 2020.

(2)      Akhavan Kazemi, M. A.; Raval, P.; Cherednichekno, K.; Chotard, J.; Krishna, A.; Demortiere, A.; Reddy, G. N. M.; Sauvage, F. Molecular‐Level Insight into Correlation between Surface Defects and Stability of Methylammonium Lead Halide Perovskite Under Controlled Humidity. Small Methods 2020, 2000834.

We would like to acknowledge University of Lille and Region Haut-de-France for the financial support.

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