Entropy stabilization effects and ion migration in 3D “hollow” halide perovskites
<p>A recently discovered new family of 3D halide perovskites with the general formula (A)<sub>1–<em>x</em></sub>(<em>en</em>)<sub><em>x</em></sub>(Pb)<sub>1–0.7<em>x</em></sub>(X)<sub>...
| Main Authors: | , , , , , , , |
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| Format: | Journal article |
| Language: | English |
| Published: |
American Chemical Society
2022
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| _version_ | 1797109544341471232 |
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| author | Jayanthi, K Spanopoulos, I Zibouche, N Voskanyan, AA Vasileiadou, ES Islam, MS Navrotsky, A Kanatzidis, MG |
| author_facet | Jayanthi, K Spanopoulos, I Zibouche, N Voskanyan, AA Vasileiadou, ES Islam, MS Navrotsky, A Kanatzidis, MG |
| author_sort | Jayanthi, K |
| collection | OXFORD |
| description | <p>A recently discovered new family of 3D halide perovskites with the general formula (A)<sub>1–<em>x</em></sub>(<em>en</em>)<sub><em>x</em></sub>(Pb)<sub>1–0.7<em>x</em></sub>(X)<sub>3–0.4<em>x</em></sub> (A = MA, FA; X = Br, I; MA = methylammonium, FA = formamidinium, <em>en</em> = ethylenediammonium) is referred to as “hollow” perovskites owing to extensive Pb and X vacancies created on incorporation of <em>en</em> cations in the 3D network. The “hollow” motif allows fine tuning of optical, electronic, and transport properties and bestowing good environmental stability proportional to <em>en</em> loading. To shed light on the origin of the apparent stability of these materials, we performed detailed thermochemical studies, using room temperature solution calorimetry combined with density functional theory simulations on three different families of “hollow” perovskites namely <em>en</em>/FAPbI<sub>3</sub>, <em>en</em>/MAPbI<sub>3</sub>, and <em>en</em>/FAPbBr<sub>3</sub>. We found that the bromide perovskites are more energetically stable compared to iodide perovskites in the FA-based hollow compounds, as shown by the measured enthalpies of formation and the calculated formation energies. The least stable FAPbI<sub>3</sub> gains stability on incorporation of the <em>en</em> cation, whereas FAPbBr<sub>3</sub> becomes less stable with <em>en</em> loading. This behavior is attributed to the difference in the 3D cage size in the bromide and iodide perovskites. Configurational entropy, which arises from randomly distributed cation and anion vacancies, plays a significant role in stabilizing these “hollow” perovskite structures despite small differences in their formation enthalpies. With the increased vacancy defect population, we have also examined halide ion migration in the FA-based “hollow” perovskites and found that the migration energy barriers become smaller with the increasing <em>en</em> content.</p> |
| first_indexed | 2024-03-07T07:41:43Z |
| format | Journal article |
| id | oxford-uuid:f450dfe2-3e53-4b99-84de-a617b45b1079 |
| institution | University of Oxford |
| language | English |
| last_indexed | 2024-03-07T07:41:43Z |
| publishDate | 2022 |
| publisher | American Chemical Society |
| record_format | dspace |
| spelling | oxford-uuid:f450dfe2-3e53-4b99-84de-a617b45b10792023-04-28T11:28:41ZEntropy stabilization effects and ion migration in 3D “hollow” halide perovskitesJournal articlehttp://purl.org/coar/resource_type/c_dcae04bcuuid:f450dfe2-3e53-4b99-84de-a617b45b1079EnglishSymplectic ElementsAmerican Chemical Society2022Jayanthi, KSpanopoulos, IZibouche, NVoskanyan, AAVasileiadou, ESIslam, MSNavrotsky, AKanatzidis, MG<p>A recently discovered new family of 3D halide perovskites with the general formula (A)<sub>1–<em>x</em></sub>(<em>en</em>)<sub><em>x</em></sub>(Pb)<sub>1–0.7<em>x</em></sub>(X)<sub>3–0.4<em>x</em></sub> (A = MA, FA; X = Br, I; MA = methylammonium, FA = formamidinium, <em>en</em> = ethylenediammonium) is referred to as “hollow” perovskites owing to extensive Pb and X vacancies created on incorporation of <em>en</em> cations in the 3D network. The “hollow” motif allows fine tuning of optical, electronic, and transport properties and bestowing good environmental stability proportional to <em>en</em> loading. To shed light on the origin of the apparent stability of these materials, we performed detailed thermochemical studies, using room temperature solution calorimetry combined with density functional theory simulations on three different families of “hollow” perovskites namely <em>en</em>/FAPbI<sub>3</sub>, <em>en</em>/MAPbI<sub>3</sub>, and <em>en</em>/FAPbBr<sub>3</sub>. We found that the bromide perovskites are more energetically stable compared to iodide perovskites in the FA-based hollow compounds, as shown by the measured enthalpies of formation and the calculated formation energies. The least stable FAPbI<sub>3</sub> gains stability on incorporation of the <em>en</em> cation, whereas FAPbBr<sub>3</sub> becomes less stable with <em>en</em> loading. This behavior is attributed to the difference in the 3D cage size in the bromide and iodide perovskites. Configurational entropy, which arises from randomly distributed cation and anion vacancies, plays a significant role in stabilizing these “hollow” perovskite structures despite small differences in their formation enthalpies. With the increased vacancy defect population, we have also examined halide ion migration in the FA-based “hollow” perovskites and found that the migration energy barriers become smaller with the increasing <em>en</em> content.</p> |
| spellingShingle | Jayanthi, K Spanopoulos, I Zibouche, N Voskanyan, AA Vasileiadou, ES Islam, MS Navrotsky, A Kanatzidis, MG Entropy stabilization effects and ion migration in 3D “hollow” halide perovskites |
| title | Entropy stabilization effects and ion migration in 3D “hollow” halide perovskites |
| title_full | Entropy stabilization effects and ion migration in 3D “hollow” halide perovskites |
| title_fullStr | Entropy stabilization effects and ion migration in 3D “hollow” halide perovskites |
| title_full_unstemmed | Entropy stabilization effects and ion migration in 3D “hollow” halide perovskites |
| title_short | Entropy stabilization effects and ion migration in 3D “hollow” halide perovskites |
| title_sort | entropy stabilization effects and ion migration in 3d hollow halide perovskites |
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