Role of Alkali Cations in Stabilizing Mixed-Cation Perovskites to Thermal Stress and Moisture Conditions.

Autor: Maniyarasu S; Department of Physics and Astronomy, School of Natural Sciences, The University of Manchester, Oxford Road, Manchester M13 9PL, U.K.; Photon Science Institute, The University of Manchester, Oxford Road, Manchester M13 9PL, U.K., Ke JC; Department of Physics and Astronomy, School of Natural Sciences, The University of Manchester, Oxford Road, Manchester M13 9PL, U.K.; Photon Science Institute, The University of Manchester, Oxford Road, Manchester M13 9PL, U.K., Spencer BF; Department of Materials, School of Natural Sciences, The University of Manchester, Oxford Road, Manchester M13 9PL, U.K.; Henry Royce Institute, The University of Manchester, Oxford Road, Manchester M13 9PL, U.K., Walton AS; Photon Science Institute, The University of Manchester, Oxford Road, Manchester M13 9PL, U.K.; Department of Chemistry, School of Natural Sciences, The University of Manchester, Oxford Road, Manchester M13 9PL, U.K., Thomas AG; Photon Science Institute, The University of Manchester, Oxford Road, Manchester M13 9PL, U.K.; Department of Materials, School of Natural Sciences, The University of Manchester, Oxford Road, Manchester M13 9PL, U.K.; Henry Royce Institute, The University of Manchester, Oxford Road, Manchester M13 9PL, U.K., Flavell WR; Department of Physics and Astronomy, School of Natural Sciences, The University of Manchester, Oxford Road, Manchester M13 9PL, U.K.; Photon Science Institute, The University of Manchester, Oxford Road, Manchester M13 9PL, U.K.; Henry Royce Institute, The University of Manchester, Oxford Road, Manchester M13 9PL, U.K.
Jazyk: angličtina
Zdroj: ACS applied materials & interfaces [ACS Appl Mater Interfaces] 2021 Sep 15; Vol. 13 (36), pp. 43573-43586. Date of Electronic Publication: 2021 Aug 31.
DOI: 10.1021/acsami.1c10420
Abstrakt: Perovskite solar cells (PSCs) based on organic-inorganic hybrid perovskites containing a small fraction of substituted alkali-metal cations have shown remarkable performance and stability. However, the role of these cations is unclear. The thermal- and moisture-induced degradation of FA 1- x Cs x PbI 3 and (FA 1- x Cs x ) 1- y Rb y PbI 3 (where FA represents formamidinium, x , y = 0.1, 0.05) is investigated using in situ photoelectron spectroscopy (PES). Both compositions exhibit superior moisture stability compared with methylammonium lead iodide under 9 mbar of water vapor. Ga Kα hard X-ray PES is used to investigate the composition of the perovskites at depths up to 45 nm into the surface. This allows more accurate quantification of the alkali-metal distribution than is possible using conventional X-ray PES. The addition of RbI results in a fairly homogeneous distribution of both Cs + and Rb + in the surface layers (in contrast to surface Cs depletion seen in its absence), together with a marked reduction in surface iodide vacancies. Overall, RbI is found to play a critical role in increasing the thermal stability of FA 1- x Cs x PbI 3 by providing a source of I - that fills iodine vacancy sites in the perovskite lattice, while Rb + is not substantially incorporated into the perovskite. We suggest that the concomitant increase in ion migration barriers in the surface layers is key to improved PSC performance and long-lasting stability.
Databáze: MEDLINE
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