Charles, Bethan, Weller, Mark T., Rieger, Sebastian, Hatcher, Lauren E.  ORCID: https://orcid.org/0000-0002-1549-9727, Henry, Paul F., Feldmann, Jochen, Wolverson, Daniel and Wilson, Chick C.
2020.
Phase behavior and substitution limit of mixed cesium-formamidinium lead triiodide perovskites.
Chemistry of Materials
32
(6)
, pp. 2282-2291.
10.1021/acs.chemmater.9b04032
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Abstract
The mixed cation lead iodide perovskite photovoltaics show improved stability following site substitution of cesium ions (Cs+) onto the formamidinium cation sites (FA+) of (CH(NH2)2PbI3 (FAPbI3) and increased resistance to formation of the undesirable ∂-phase. The structural phase behavior of Cs0.1FA0.9PbI3 has been investigated by neutron powder diffraction (NPD), complemented by single crystal and power X-ray diffraction and photoluminescence spectroscopy. The Cs-substitution limit has been determined to be less than 15%, and the cubic α-phase, Cs0.1FA0.9PbI3, is shown to be synthesizable in bulk and stable at 300 K. On cooling the cubic Cs0.1FA0.9PbI3, a slow, second-order cubic to tetragonal transition is observed close to 290 K, with variable temperature NPD indicating the presence of the tetragonal β-phase, adopting the space group P4/mbm between 290 and 180 K. An orthorhombic phase or twinned tetragonal phase is formed below 180 K, and the temperature for further transition to a disordered state is lowered to 125 K compared to that seen in phase pure α-FAPbI3 (140 K). These results demonstrate the importance of understanding the effect of cation site substitution on structure–property relationships in perovskite materials.
| Item Type: | Article |
|---|---|
| Date Type: | Publication |
| Status: | Published |
| Schools: | Schools > Chemistry |
| Publisher: | American Chemical Society |
| ISSN: | 0897-4756 |
| Funders: | EPSRC |
| Date of First Compliant Deposit: | 19 March 2020 |
| Date of Acceptance: | 27 February 2020 |
| Last Modified: | 02 Dec 2024 03:30 |
| URI: | https://orca.cardiff.ac.uk/id/eprint/130516 |
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