Tracking the formation of methylammonium lead triiodide perovskite

Journal Article · Mon Aug 10 00:00:00 EDT 2015 · Applied Physics Letters

DOI:https://doi.org/10.1063/1.4928662· OSTI ID:22489082

Liu, Lijia; Wang, Rongbin; Shen, Pengfei; Duhm, Steffen ^[1]

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1. Jiangsu Key Laboratory for Carbon-Based Functional Materials and Devices, Institute of Functional Nano and Soft Materials (FUNSOM), Soochow University, 199 Ren'ai Road, Suzhou, Jiangsu 215123 (China)

The formation mechanism of perovskite methylammonium lead triiodide (CH{sub 3}NH{sub 3}PbI{sub 3}) was studied with in situ X-ray photoelectron spectroscopy (XPS) on successive depositions of thermally evaporated methylammonium iodide (CH{sub 3}NH{sub 3}I) on a lead iodide (PbI{sub 2}) film. This deposition method mimics the “two-step” synthesis method commonly used in device fabrication. We find that several competing processes occur during the formation of perovskite CH{sub 3}NH{sub 3}PbI{sub 3}. Our most important finding is that during vapour deposition of CH{sub 3}NH{sub 3}I onto PbI{sub 2}, at least two carbon species are present in the resulting material, while only one nitrogen species is present. This suggests that CH{sub 3}NH{sub 3}I can dissociate during the transition to a perovskite phase, and some of the resulting molecules can be incorporated into the perovskite. The effect of partial CH{sub 3}NH{sub 3} substitution with CH{sub 3} was evaluated, and electronic structure calculations show that CH{sub 3} defects would impact the photovoltaic performance in perovskite solar cells. The possibility that not all A sites in the APbI{sub 3} perovskite are occupied by CH{sub 3}NH{sub 3} is therefore an important consideration when evaluating the performance of organometallic trihalide solar cells synthesized using typical approaches.

• OSTI ID: 22489082
• Journal Information: Applied Physics Letters, Vol. 107, Issue 6; Other Information: (c) 2015 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA); ISSN 0003-6951
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC
ORGANIC
PHYSICAL AND ANALYTICAL CHEMISTRY
71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
CARBON
DEPOSITION
ELECTRONIC STRUCTURE
FABRICATION
FILMS
LEAD
LEAD IODIDES
MOLECULES
NITROGEN
ORGANOMETALLIC COMPOUNDS
PERFORMANCE
PEROVSKITE
PHOTOVOLTAIC EFFECT
SOLAR CELLS
SYNTHESIS
VAPORS
X-RAY PHOTOELECTRON SPECTROSCOPY