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Temperature‐Dependent Charge‐Carrier Dynamics in CH 3 NH 3 PbI 3 Perovskite Thin Films
Author(s) -
Milot Rebecca L.,
Eperon Giles E.,
Snaith Henry J.,
Johnston Michael B.,
Herz Laura M.
Publication year - 2015
Publication title -
advanced functional materials
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 6.069
H-Index - 322
eISSN - 1616-3028
pISSN - 1616-301X
DOI - 10.1002/adfm.201502340
Subject(s) - materials science , charge carrier , perovskite (structure) , atmospheric temperature range , phase (matter) , diffusion , photoluminescence , photoconductivity , tetragonal crystal system , impurity , analytical chemistry (journal) , condensed matter physics , optoelectronics , crystallography , chemistry , physics , organic chemistry , chromatography , meteorology , thermodynamics
The photoluminescence, transmittance, charge‐carrier recombination dynamics, mobility, and diffusion length of CH 3 NH 3 PbI 3 are investigated in the temperature range from 8 to 370 K. Profound changes in the optoelectronic properties of this prototypical photovoltaic material are observed across the two structural phase transitions occurring at 160 and 310 K. Drude‐like terahertz photoconductivity spectra at all temperatures above 80 K suggest that charge localization effects are absent in this range. The monomolecular charge‐carrier recombination rate generally increases with rising temperature, indicating a mechanism dominated by ionized impurity mediated recombination. Deduced activation energies E a associated with ionization are found to increase markedly from the room‐temperature tetragonal ( E a ≈ 20 meV) to the higher‐temperature cubic ( E a ≈ 200 meV) phase adopted above 310 K. Conversely, the bimolecular rate constant decreases with rising temperature as charge‐carrier mobility declines, while the Auger rate constant is highly phase specific, suggesting a strong dependence on electronic band structure. The charge‐carrier diffusion length gradually decreases with rising temperature from about 3 μm at −93 °C to 1.2 μm at 67 °C but remains well above the optical absorption depth in the visible spectrum. These results demonstrate that there are no fundamental obstacles to the operation of cells based on CH 3 NH 3 PbI 3 under typical field conditions.