Abstract
Interplay between structural and photophysical properties of metal halide perovskites is critical to their utility in optoelectronics, but there is limited understanding of lattice response upon photoexcitation. Here, 2D perovskites butylammonium lead iodide, (BA)2PbI4, and phenethylammonium lead iodide, (PEA)2PbI4, are investigated using ultrafast transient X-ray diffraction as a function of optical excitation fluence to discern structural dynamics. Both powder X-ray diffraction and time-resolved photoluminescence linewidths narrow over 1 ns following optical excitation for the fluence range studied, concurrent with slight redshifting of the optical bandgaps. These observations are attributed to transient relaxation and ordering of distorted lead iodide octahedra stimulated mainly by electron–hole pair creation. The c axis expands up to 0.37% over hundreds of picoseconds; reflections sampling the a and b axes undergo one tenth of this expansion with the same timescale. Post-photoexcitation appearance of the (110) reflection in (BA)2PbI4 would suggest a transient phase transition, however, through new single-crystal XRD, reflections are found that violate glide plane conditions in the reported Pbca structure. The static structure space group is reassigned as P212121. With this, a nonequilibrium phase transition is ruled out. These findings offer increased understanding of remarkable lattice response in 2D perovskites upon excitation.
| Original language | English (US) |
|---|---|
| Article number | 2202709 |
| Journal | Advanced Materials |
| Volume | 34 |
| Issue number | 44 |
| DOIs | |
| State | Published - Nov 3 2022 |
Funding
Work performed at the Center for Nanoscale Materials and Advanced Photon Source, both U.S. Department of Energy Office of Science User Facilities, was supported by the U.S. DOE, Office of Basic Energy Sciences, under Contract No. DE-AC02-06CH11357. At Northwestern University, this work is supported by the Department of Energy, Office of Science, Basic Energy Sciences, under Grant No. SC0012541 (M.G.K., synthesis, structure, and characterization of physical properties) and by the National Science Foundation Macromolecular, Supramolecular, and Nanochemistry Award No.1808590 for elevated fluence optical investigation. This work made use of the IMSERC facility at Northwestern University, which has received support from the Soft and Hybrid Nanotechnology Experimental (SHyNE) Resource (NSF ECCS-2025633), and Northwestern University. Purchase of the Ag-microsource diffractometer used to obtain results included in this publication was supported by the Major Research Instrumentation Program from the National Science Foundation under the Award No. CHE-1920248. This material is based upon work supported by the National Science Foundation Graduate Research Fellowship Program under Grant No. DGE-1842165 (S.P. and A.B.). A.M.L. acknowledges support from by the Department of Energy, Office of Science, Basic Energy Sciences, Materials Sciences and Engineering Division, under Contract DE-AC02-76SF00515. This work was performed with financial support from the European Union's Horizon 2020 program through an Innovation Action under grant Agreement No. 861985 (PEROCUBE). J.E. acknowledges financial support from the Institute Universitaire de France. This work was granted access to the HPC resources of [TGCC/CINES/IDRIS] under the allocations 2020-A0100911434 and 2020-A0090907682 made by GENCI. Work performed at the Center for Nanoscale Materials and Advanced Photon Source, both U.S. Department of Energy Office of Science User Facilities, was supported by the U.S. DOE, Office of Basic Energy Sciences, under Contract No. DE‐AC02‐06CH11357. At Northwestern University, this work is supported by the Department of Energy, Office of Science, Basic Energy Sciences, under Grant No. SC0012541 (M.G.K., synthesis, structure, and characterization of physical properties) and by the National Science Foundation Macromolecular, Supramolecular, and Nanochemistry Award No.1808590 for elevated fluence optical investigation. This work made use of the IMSERC facility at Northwestern University, which has received support from the Soft and Hybrid Nanotechnology Experimental (SHyNE) Resource (NSF ECCS‐2025633), and Northwestern University. Purchase of the Ag‐microsource diffractometer used to obtain results included in this publication was supported by the Major Research Instrumentation Program from the National Science Foundation under the Award No. CHE‐1920248. This material is based upon work supported by the National Science Foundation Graduate Research Fellowship Program under Grant No. DGE‐1842165 (S.P. and A.B.). A.M.L. acknowledges support from by the Department of Energy, Office of Science, Basic Energy Sciences, Materials Sciences and Engineering Division, under Contract DE‐AC02‐76SF00515. This work was performed with financial support from the European Union's Horizon 2020 program through an Innovation Action under grant Agreement No. 861985 (PEROCUBE). J.E. acknowledges financial support from the Institute Universitaire de France. This work was granted access to the HPC resources of [TGCC/CINES/IDRIS] under the allocations 2020‐A0100911434 and 2020‐A0090907682 made by GENCI.
Keywords
- lead halide perovskites
- optical excitation
- transient structures
ASJC Scopus subject areas
- General Materials Science
- Mechanics of Materials
- Mechanical Engineering