Hidden polymorphism of FAPbI3 discovered by Raman spectroscopy
| Autor: | René Gunder, Bernd Szyszka, Sri Hari Bharath Vinoth Kumar, Markus R. Wagner, Axel Hoffmann, Pamela Rosado, Ruslan Muydinov, Josefa Ibaceta-Jaña |
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| Rok vydání: | 2021 |
| Předmět: |
chemistry.chemical_classification
Materials science Annealing (metallurgy) Iodide Analytical chemistry General Physics and Astronomy 02 engineering and technology 010402 general chemistry 021001 nanoscience & nanotechnology 01 natural sciences 0104 chemical sciences symbols.namesake Formamidinium chemistry Polymorphism (materials science) Attenuation coefficient Phase (matter) ddc:540 symbols Photovoltaics and Wind Energy Thermal stability Physical and Theoretical Chemistry 0210 nano-technology Raman spectroscopy |
| Zdroj: | Physical Chemistry Chemical Physics. 23:9476-9482 |
| ISSN: | 1463-9084 1463-9076 |
| DOI: | 10.1039/d1cp00102g |
| Popis: | Formamidinium lead iodide FAPbI3 can be used in its cubic, black form as a light absorber material in single junction solar cells. It has a band gap 1.5 eV close to the maximum of the Shockley Queisser limit, and reveals a high absorption coefficient. Its high thermal stability up to 320 C has also a downside, which is the instability of the photo active form at room temperature RT . Thus, the black amp; 945; phase transforms at RT with time into a yellow non photo active amp; 948; phase. The black phase can be recovered by annealing of the yellow state. In this work, a polymorphism of the amp; 945; phase at room temperature was found as synthesized amp; 945;i , degraded amp; 945; amp; 948; and thermally recovered amp; 945;rec . They differ in the Raman spectra and PL signal, but not in the XRD patterns. Using temperature dependent Raman spectroscopy, we identified a structural change in the amp; 945;i polymorph at ca. 110 C. Above 110 C, the FAPbI3 structure has undoubtedly cubic Pm[3 with combining macron]m symmetry high temperature phase amp; 945;HT . Below that temperature, the amp; 945;i phase was suggested to have a distorted perovskite structure with Im[3 with combining macron] symmetry. Thermally recovered FAPbI3 amp; 945;rec also demonstrated the structural transition to amp; 945;HT at the same temperature ca. 110 C during its heating. The understanding of hybrid perovskites may bring additional assets in the development of new and stable structures |
| Databáze: | OpenAIRE |
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