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Title: Pressure-induced dramatic changes in organic–inorganic halide perovskites


We summarise cutting-edge discoveries and provide insights into the important theme of halide perovskites using pressure as a tuning tool.

ORCiD logo [1];  [2]; ORCiD logo [3]; ORCiD logo [1]
  1. Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
  2. Center for High Pressure Science and Technology Advanced Research, Shanghai (China)
  3. Los Alamos National Lab. (LANL), Los Alamos, NM (United States); State Univ. of New York (SUNY), Buffalo, NY (United States). Dept. of Materials Design and Innovation
Publication Date:
Research Org.:
Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
Sponsoring Org.:
USDOE National Nuclear Security Administration (NNSA)
OSTI Identifier:
Report Number(s):
Journal ID: ISSN 2041-6520; CSHCBM; TRN: US1800375
Grant/Contract Number:
Resource Type:
Journal Article: Accepted Manuscript
Journal Name:
Chemical Science
Additional Journal Information:
Journal Volume: 8; Journal Issue: 10; Journal ID: ISSN 2041-6520
Royal Society of Chemistry
Country of Publication:
United States

Citation Formats

Lü, Xujie, Yang, Wenge, Jia, Quanxi, and Xu, Hongwu. Pressure-induced dramatic changes in organic–inorganic halide perovskites. United States: N. p., 2017. Web. doi:10.1039/C7SC01845B.
Lü, Xujie, Yang, Wenge, Jia, Quanxi, & Xu, Hongwu. Pressure-induced dramatic changes in organic–inorganic halide perovskites. United States. doi:10.1039/C7SC01845B.
Lü, Xujie, Yang, Wenge, Jia, Quanxi, and Xu, Hongwu. 2017. "Pressure-induced dramatic changes in organic–inorganic halide perovskites". United States. doi:10.1039/C7SC01845B.
title = {Pressure-induced dramatic changes in organic–inorganic halide perovskites},
author = {Lü, Xujie and Yang, Wenge and Jia, Quanxi and Xu, Hongwu},
abstractNote = {We summarise cutting-edge discoveries and provide insights into the important theme of halide perovskites using pressure as a tuning tool.},
doi = {10.1039/C7SC01845B},
journal = {Chemical Science},
number = 10,
volume = 8,
place = {United States},
year = 2017,
month = 8

Journal Article:
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  • Mixed halide hybrid perovskites, CH 3NH 3Pb(I 1-xBrx) 3' represent good candidates for lowcost, high efficiency photovoltaic, and light-emitting devices. Their band gaps can be tuned from 1.6 to 2.3 eV, by changing the halide anion identity. Unfortunately, mixed halide perovskites undergo phase separation under illumination. This leads to iodide- and bromide-rich domains along with corresponding changes to the material’s optical/electrical response. Here, using combined spectroscopic measurements and theoretical modeling, we quantitatively rationalize all microscopic processes that occur during phase separation. Our model suggests that the driving force behind phase separation is the bandgap reduction of iodiderich phases. It additionallymore » explains observed non-linear intensity dependencies, as well as self-limited growth of iodide-rich domains. Most importantly, our model reveals that mixed halide perovskites can be stabilized against phase separation by deliberately engineering carrier diffusion lengths and injected carrier densities.« less
  • No abstract prepared.
  • Solution-processable methylammonium lead trihalide perovskites exhibit remarkable high-absorption and low-loss properties for solar energy conversion. Calculation from density functional theory indicates the presence of non-equivalent halogen atoms in the unit cell because of the specific orientation of the organic cation. Considering the 〈100〉 orientation as an example, I{sub 1}, one of the halogen atoms, differs from the other iodine atoms (I{sub 2} and I{sub 3}) in terms of its interaction with the organic cation. The valance-band-maximum (VBM) and conduction-band-minimum (CBM) states are derived mainly from 5p orbital of I{sub 1} atom and 6p orbital of Pb atom, respectively. The spatiallymore » separated charge densities of the electrons and holes justify the low recombination rate of the pure iodide perovskite. Chlorine substitution further strengthens the unique position of the I{sub 1} atom, leading to more localized charge density around the I{sub 1} atom and less charge density around the other atoms at the VBM state. The less overlap of charge densities between the VBM and CBM states explains the relatively lower carrier recombination rate of the iodine-chlorine mixed perovskite. Chlorine substitution significantly reduces the effective mass at a direction perpendicular to the Pb-Cl bond and organic axis, enhancing the carrier transport property of the mixed perovskite in this direction.« less
  • Carrier dynamics in methylammonium lead halide (CH3NH3PbI3-xClx) perovskite thin films, of differing crystal morphology, are examined as functions of temperature and excitation wavelength. At room temperature, long-lived (> nanosecond) transient absorption signals indicate negligible carrier trapping. However, in measurements of ultrafast photoluminescence excited at 400 nm, a heretofore unexplained, large amplitude (50%-60%), 45 ps decay process is observed. This feature persists for temperatures down to the orthorhombic phase transition. Varying pump photon energy reveals that the fast, band-edge photoluminescence (PL) decay only appears for excitation >= 2.38 eV (520 nm), with larger amplitudes for higher pump energies. Lower photon-energy excitationmore » yields slow dynamics consistent with negligible carrier trapping. Further, sub-bandgap two-photon pumping yields identical PL dynamics as direct absorption, signifying sensitivity to the total deposited energy and insensitivity to interfacial effects. Together with first principles electronic structure and ab initio molecular dynamics calculations, the results suggest the fast PL decay stems from excitation of high energy phonon modes associated with the organic sub-lattice that temporarily enhance wavefunction overlap within the inorganic component owing to atomic displacement, thereby transiently changing the PL radiative rate during thermalization. Hence, the fast PL decay relates a characteristic organic-to-inorganic sub-lattice equilibration timescale at optoelectronic-relevant excitation energies.« less