Krajewska, CJ;
Kavanagh, SR;
Zhang, L;
Kubicki, DJ;
Dey, K;
Galkowski, K;
Grey, CP;
... Palgrave, RG; + view all
(2021)
Enhanced visible light absorption in layered Cs_{3}Bi_{2}Br_+{9} through mixed-valence Sn(II)/Sn(IV) doping.
Chemical Science
10.1039/d1sc03775g.
(In press).
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Abstract
Lead-free halides with perovskite-related structures, such as the vacancy-ordered perovskite Cs_{3}Bi_{2}Br_{9}, are of interest for photovoltaic and optoelectronic applications. We find that addition of SnBr2 to the solution-phase synthesis of Cs_{3}Bi_{2}Br_{9} leads to substitution of up to 7% of the Bi(III) ions by equal quantities of Sn(II) and Sn(IV). The nature of the substitutional defects was studied by X-ray diffraction, {133}^Cs and {119}^Sn solid state NMR, X-ray photoelectron spectroscopy and density functional theory calculations. The resulting mixed-valence compounds show intense visible and near infrared absorption due to intervalence charge transfer, as well as electronic transitions to and from localised Sn-based states within the band gap. Sn(II) and Sn(IV) defects preferentially occupy neighbouring B-cation sites, forming a double-substitution complex. Unusually for a Sn(II) compound, the material shows minimal changes in optical and structural properties after 12 months storage in air. Our calculations suggest the stabilisation of Sn(II) within the double substitution complex contributes to this unusual stability. These results expand upon research on inorganic mixed-valent halides to a new, layered structure, and offer insights into the tuning, doping mechanisms, and structure–property relationships of lead-free vacancy-ordered perovskite structures.
| Type: | Article |
|---|---|
| Title: | Enhanced visible light absorption in layered Cs_{3}Bi_{2}Br_+{9} through mixed-valence Sn(II)/Sn(IV) doping |
| Open access status: | An open access version is available from UCL Discovery |
| DOI: | 10.1039/d1sc03775g |
| Publisher version: | https://doi.org/10.1039/D1SC03775G |
| Language: | English |
| Additional information: | © Royal Society of Chemistry 2021. This article is Open Access (http://creativecommons.org/licenses/by/3.0/). |
| UCL classification: | UCL UCL > Provost and Vice Provost Offices > UCL BEAMS UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Maths and Physical Sciences UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Maths and Physical Sciences > Dept of Chemistry |
| URI: | https://discovery-pp.ucl.ac.uk/id/eprint/10137093 |
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