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Issue 3, 2018
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Iodine chemistry determines the defect tolerance of lead-halide perovskites

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Abstract

Metal-halide perovskites are outstanding materials for photovoltaics. Their long carrier lifetimes and diffusion lengths favor efficient charge collection, leading to efficiencies competing with established photovoltaics. These observations suggest an apparently low density of traps in the prototype methylammonium lead iodide (MAPbI3) contrary to the expected high defect density of a low-temperature, solution-processed material. Combining first-principles calculations and spectroscopic measurements we identify less abundant iodine defects as the source of photochemically active deep electron and hole traps in MAPbI3. The peculiar iodine redox chemistry leads, however, to kinetic deactivation of filled electron traps, leaving only short-living hole traps as potentially harmful defects. Under mild oxidizing conditions the amphoteric hole traps can be converted into kinetically inactive electron traps, providing a rationale for the defect tolerance of metal-halide perovskites. Bromine and chlorine doping of MAPbI3 also inactivate hole traps, possibly explaining the superior optoelectronic properties of mixed-halide perovskites.

Graphical abstract: Iodine chemistry determines the defect tolerance of lead-halide perovskites

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Publication details

The article was received on 13 Jan 2018, accepted on 06 Feb 2018 and first published on 09 Feb 2018


Article type: Paper
DOI: 10.1039/C8EE00124C
Citation: Energy Environ. Sci., 2018,11, 702-713
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    Iodine chemistry determines the defect tolerance of lead-halide perovskites

    D. Meggiolaro, S. G. Motti, E. Mosconi, A. J. Barker, J. Ball, C. Andrea Riccardo Perini, F. Deschler, A. Petrozza and F. De Angelis, Energy Environ. Sci., 2018, 11, 702
    DOI: 10.1039/C8EE00124C

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