Influence of Inorganic Layer Thickness on Methylammonium Dynamics in Hybrid Perovskite Derivatives
Abstract
The layered Ruddlesden–Popper derivatives of CH₃NH₃PbI₃ have recently emerged as high-performing materials for photovoltaics with improved stability. The inclusion of organic molecules within the inorganic framework provides additional dynamic degrees of freedom that influence the optoelectronic properties. The rotational dynamics of CH₃NH₃⁺ influence dielectric behavior and electronic excited-state dynamics in CH₃NH₃PbI₃; however, the influence of cation dynamics on properties in the layered derivatives has not yet been determined. We employ quasi-elastic neutron scattering to study the rotational dynamics of methylammonium (CH₃NH₃⁺, MA) and deuterated n-butylammonium (CD₃(CD₂)₃NH⁺₃, d-nBA) in (d-nBA)₂(MA)ₙ₋₁PbₙI₃ₙ₊₁ (n = 2, 3). (d-nBA)₂(MA)₂Pb₃I₁₀ exhibits shorter residence times of the CH₃NH₃⁺ and CD₃(CD₂)₃NH⁺₃ reorientational motions, which are attributed to the larger volumes that the cations occupy in the inorganic framework and to the dimensionality of the inorganic layer by way of dielectric screening between the organic cations. Discontinuities in the mean-squared displacement of overall hydrogen motion determined by fixed-window elastic neutron scattering are consistent with phase transitions observed by differential scanning calorimetry and time-resolved microwave conductivity signals. Determining how the dimensionality of the inorganic layer influences the organic cation rotational dynamics provides fundamental chemical insight into how the electronic dynamics vary between n-members.
Additional Information
The work was supported by the grant SC0016083 funded by the U.S. Department of Energy, Office of Science. J.R.N. and A.A.K. acknowledge partial support from Research Corporation for Science Advancement through a Cottrell Scholar Award. A portion of this research used resources from the Center for Neutron Research, National Institute of Standards and Technology, U.S. Department of Commerce, for neutron research used in this work. The authors wish to thank the Analytical Resources Core (RRID: SCR_021758) at Colorado State University for instrument access, training, and assistance with sample analysis. Access to HFBS was provided by the Center for high-resolution Neutron Scattering, a partnership between the National Institute of Standards and Technology and the National Science Foundation under agreement no. DMR-1508249. The identification of any commercial product or trade name does not imply endorsement or recommendation by NIST. We honor the Colorado State University land acknowledgment, https://landacknowledgment.colostate.edu.Additional details
- Eprint ID
- 117124
- Resolver ID
- CaltechAUTHORS:20220923-941669700.7
- SC-0016083
- Department of Energy (DOE)
- Cottrell Scholar of Research Corporation
- National Institute of Standards and Technology (NIST)
- DMR-150824
- NSF
- Created
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2022-10-04Created from EPrint's datestamp field
- Updated
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2022-10-04Created from EPrint's last_modified field