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Media type:
E-Article
Title:
Identification of lead vacancy defects in lead halide perovskites
Contributor:
Keeble, David J.;
Wiktor, Julia;
Pathak, Sandeep K.;
Phillips, Laurie J.;
Dickmann, Marcel;
Durose, Ken;
Snaith, Henry J.;
Egger, Werner
imprint:
Springer Science and Business Media LLC, 2021
Published in:Nature Communications
Language:
English
DOI:
10.1038/s41467-021-25937-1
ISSN:
2041-1723
Origination:
Footnote:
Description:
<jats:title>Abstract</jats:title><jats:p>Perovskite photovoltaics advance rapidly, but questions remain regarding point defects: while experiments have detected the presence of electrically active defects no experimentally confirmed microscopic identifications have been reported. Here we identify lead monovacancy (V<jats:sub>Pb</jats:sub>) defects in MAPbI<jats:sub>3</jats:sub> (MA = CH<jats:sub>3</jats:sub>NH<jats:sub>3</jats:sub><jats:sup>+</jats:sup>) using positron annihilation lifetime spectroscopy with the aid of density functional theory. Experiments on thin film and single crystal samples all exhibited dominant positron trapping to lead vacancy defects, and a minimum defect density of ~3 × 10<jats:sup>15</jats:sup> cm<jats:sup>−3</jats:sup> was determined. There was also evidence of trapping at the vacancy complex <jats:inline-formula><jats:alternatives><jats:tex-math>$$({{{{{\rm{V}}}}}}_{{{{{\rm{Pb}}}}}}{{{{{\rm{V}}}}}}_{{{{{\rm{I}}}}}})^{-}$$</jats:tex-math><mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML">
<mml:msup>
<mml:mrow>
<mml:mrow>
<mml:mo>(</mml:mo>
<mml:mrow>
<mml:msub>
<mml:mrow>
<mml:mi>V</mml:mi>
</mml:mrow>
<mml:mrow>
<mml:mi>Pb</mml:mi>
</mml:mrow>
</mml:msub>
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<mml:mi>V</mml:mi>
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</mml:math></jats:alternatives></jats:inline-formula> in a minority of samples, but no trapping to MA-ion vacancies was observed. Our experimental results support the predictions of other first-principles studies that deep level, hole trapping, <jats:inline-formula><jats:alternatives><jats:tex-math>$${{{{{{\rm{V}}}}}}}_{{{{{{\rm{Pb}}}}}}}^{2-}$$</jats:tex-math><mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML">
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<mml:mi>V</mml:mi>
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<mml:mi>Pb</mml:mi>
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</mml:math></jats:alternatives></jats:inline-formula>, point defects are one of the most stable defects in MAPbI<jats:sub>3</jats:sub>. This direct detection and identification of a deep level native defect in a halide perovskite, at technologically relevant concentrations, will enable further investigation of defect driven mechanisms.</jats:p>