Organic molecular dynamics and charge-carrier lifetime in lead iodide perovskite MAPbI3

Akihiro Koda; Hirotaka Okabe; Masatoshi Hiraishi; Ryosuke Kadono; Katelyn A Dagnall; Joshua J Choi; Seung-Hun Lee

doi:10.1073/pnas.2115812119

Organic molecular dynamics and charge-carrier lifetime in lead iodide perovskite MAPbI₃

Proc Natl Acad Sci U S A. 2022 Jan 25;119(4):e2115812119. doi: 10.1073/pnas.2115812119.

Authors

Akihiro Koda^{1

2}, Hirotaka Okabe¹, Masatoshi Hiraishi¹, Ryosuke Kadono^{3

2}, Katelyn A Dagnall⁴, Joshua J Choi⁴, Seung-Hun Lee⁵

Affiliations

¹ Muon Science Laboratory and Condensed Matter Research Center, Institute of Materials Structure Science, High Energy Accelerator Research Organization (KEK), Tsukuba, Ibaraki 305-0801, Japan.
² Department of Materials Structure Science, The Graduate University for Advanced Studies, Tsukuba, Ibaraki 305-0801, Japan.
³ Muon Science Laboratory and Condensed Matter Research Center, Institute of Materials Structure Science, High Energy Accelerator Research Organization (KEK), Tsukuba, Ibaraki 305-0801, Japan; ryosuke.kadono@kek.jp shlee@virginia.edu.
⁴ Department of Chemical Engineering, University of Virginia, Charlottesville, VA 22904.
⁵ Department of Physics, University of Virginia, Charlottesville, VA 22904 ryosuke.kadono@kek.jp shlee@virginia.edu.

Abstract

The long charge carrier lifetime of the hybrid organic-inorganic perovskites (HOIPs) is the key for their remarkable performance as a solar cell material. The microscopic mechanism for the long lifetime is still in debate. Here, by using a muon spin relaxation technique that probes the fluctuation of local magnetic fields, we show that the muon depolarization rate (Δ) of a prototype HOIP methylammonium lead iodide (MAPbI₃) shows a sharp decrease with increasing temperature in two steps above 120 K and 190 K across the structural transition from orthorhombic to tetragonal structure at 162 K. Our analysis shows that the reduction of Δ is quantitatively in agreement with the expected behavior due to the rapid development of methyl ammonium (MA) jumping rotation around the C ₃ and C ₄ symmetry axes. Our results provide direct evidence for the intimate relation between the rotation of the electric dipoles of MA molecules and the charge carrier lifetime in HOIPs.

Keywords: carrier lifetime; cation dynamics; muon spin rotation; organic–inorganic hybrid perovskite.