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Anisotropic dielectric behavior of layered perovskite-like Cs3Bi2I9 crystals in the terahertz region.
- Source :
- Physical Chemistry Chemical Physics (PCCP); 11/14/2020, Vol. 22 Issue 42, p24555-24560, 6p
- Publication Year :
- 2020
-
Abstract
- The ternary metal halide perovskites have gradually attracted attention for application in the optoelectronic field, owing to their tunable crystal structure and appropriate bandgap. Lead free Cs<subscript>3</subscript>Bi<subscript>2</subscript>I<subscript>9</subscript> perovskite, with a 0D layered structure containing molecular [Bi<subscript>2</subscript>I<subscript>9</subscript>]<superscript>3−</superscript> dimers, exhibits prominent optical and electrical anisotropies. Here, the anisotropic properties of the Cs<subscript>3</subscript>Bi<subscript>2</subscript>I<subscript>9</subscript> crystals were evaluated using terahertz time-domain spectroscopy (THz-TDS); meanwhile, the effect of phonon vibration on the THz transmission was confirmed using density functional perturbation theory (DFPT). Accordingly, the refractive index and extinction coefficient are estimated using THz-TDS, thanks to the high transmission in the range of 0.2–0.9 THz. The anisotropic refractive index was observed for the Cs<subscript>3</subscript>Bi<subscript>2</subscript>I<subscript>9</subscript> crystals, and was found to be 3.2–3.7 for the (100) plane (CBI<subscript>(100)</subscript>) in contrast to 2.8–3.2 for the (001) plane (CBI<subscript>(001)</subscript>). Furthermore, the Lorentz model was employed to extract the dielectric constant of Cs<subscript>3</subscript>Bi<subscript>2</subscript>I<subscript>9</subscript>, in which anisotropy is obviously indicated by the static dielectric constant and the high-frequency dielectric constant. These anisotropic behaviors are determined by the dipole moment, which is attributed to the anisotropic packing density of [Bi<subscript>2</subscript>I<subscript>9</subscript>]<superscript>3−</superscript> dimers. This study is significant and provides a deeper insight into the anisotropic photoelectric properties of Cs<subscript>3</subscript>Bi<subscript>2</subscript>I<subscript>9</subscript>, thus contributing to the development of metal halide perovskites in the field of optoelectronics. [ABSTRACT FROM AUTHOR]
Details
- Language :
- English
- ISSN :
- 14639076
- Volume :
- 22
- Issue :
- 42
- Database :
- Complementary Index
- Journal :
- Physical Chemistry Chemical Physics (PCCP)
- Publication Type :
- Academic Journal
- Accession number :
- 146827442
- Full Text :
- https://doi.org/10.1039/d0cp04485g