Understanding morphology, microstructure, and stability of photovoltaic materials using solid-state NMR spectroscopy
Parth Raval a, Rhiannon Kennard b, Eugenia Vasileiadou c, Clayton Dahlman b, Margot Dhennin a, Tomasz Pawlak d, Mohammad Ali Akhavan Kazemi e, Olivier Lafon a, Laurent Delevoye a, Frédéric Sauvage e, Ioannis Spanopoulos c f, Pascal Roussel a, Hervé Vezin g, Micheal Chabinyc b, Thuc-Quyen Nguyen h, Mercouri Kanatzidis c, G N Manjunatha Reddy a
a Univ. Lille, CNRS, Centrale Lille Institut, Univ. Artois, UMR 8181-UCCS-Unité de Catalyse et Chimie du Solide, F-59000 Lille, France
b Materials Department, University of California, Santa Barbara, United States
c Department of Chemistry, Northwestern University, Evanston, USA, Sheridan Road, 2145, Evanston, United States
d Polish Academy of Sciences, Centre of Molecular and Macromolecular Studies, Sienkiewicza 112, 90-363 Lodz, Poland
e 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
f Department of Chemistry, Unviersity of South Florida, Tampa, Florida, USA
g Univ. Lille, CNRS,UMR-8516- LASIRE-Laboratoire de Spectroscopie pour les interactions ,la Interactions, la Réactivité et l’Environnement
h Center for Polymers and Organic Solids and Department of Chemistry and Biochemistry University of California, Santa Barbara
International Conference on Hybrid and Organic Photovoltaics
Proceedings of International Conference on Hybrid and Organic Photovoltaics (HOPV22)
València, Spain, 2022 May 19th - 25th
Organizers: Pablo Docampo, Eva Unger and Elizabeth Gibson
Oral, Parth Raval, presentation 162
DOI: https://doi.org/10.29363/nanoge.hopv.2022.162
Publication date: 20th April 2022

Solution-processed semiconductors are of great current interest for low-cost and efficient photovoltaics. Specifically, hybrid perovskites and organic semiconductors are widely used for the fabrication of emerging optoelectronic devices. Here, we present the use of solid-state NMR (ssNMR) spectroscopy to gain atomic-level insights into the microstructure, thin-film morphology, stability, and degradation pathways of the hole transporting materials (HTMs) and hybrid perovskites. Specifically, we will discuss how ssNMR techniques resolve local structures and dynamics of organic/inorganic cations in methylammonium and formamidinium lead halide perovskites (MAPbI3, FAPbX3 (X= I, Br)), FA-rich formulations, and in spiro-OMeTAD based HTMs.1–5 Multinuclear 1H, 13C, 11B, 19F, and 133Cs solid-state NMR studies allow the morphological and structural changes in perovskite and HTM thin films to be probed as a function of exposure to moisture. Our studies indicate that the stability of hybrid perovskites can be adjusted from a few days to several months, depending on the exposure conditions. In addition, the combined use of XRD, ssNMR, and EPR techniques sheds light on chemical doping mechanisms and degradation pathways of HTMs.5,6 The key learnings from this work have wider relevance to further investigations towards achieving more stable and efficient photovoltaics.


(1)      Raval, P. et al. Understanding Long-Term Moisture Stability of Crystalline and Defect Passivated Methylammonium Based Lead Iodide Perovskites. In Preparation.

(2)      Kazemi, M. A. A.; et al. Molecular-Level Insight into Correlation between Surface Defects and Stability of Methylammonium Lead Halide Perovskite Under Controlled Humidity. Small Methods 2021, 5, 2000834.

(3)      Kazemi, M. A. A.; et al. Moisture-Induced Non Equilibrium Phase Segregation in Triple Cation Mixed Halide Perovskite Monitored by in Situ Characterization Techniques and Solid-State NMR. Energy Environ. Mater. 2021. https://doi.org/10.1002/eem2.12335.

(4)      Spanopoulos, I. et al. Tunable Broad Light Emission from 3D “Hollow” Bromide Perovskites through Defect Engineering. J. Am. Chem. Soc. 2021, 143, 7069–7080.

(5)      Raval, P. et al. Understanding the P-Doping of Spiro-OMeTAD by Tris(Pentafluorophenyl)Borane. Submitted.

(6)      Dixon, A. L. et al. Structural Insights into Lewis Acid- and F4TCNQ-Doped Conjugated Polymers by Solid-State Magnetic Resonance Spectroscopy. Mater. Horizons 2022, 9, 981–990.

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