Microwave measurements of dielectric constants of Snl2 and Snl4

Desai, C. C.; L., J.; Vyas, Anil

doi:10.1007/bf01203491

Cited by 8 publications

(4 citation statements)

References 7 publications

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“…These values are found to be comparable with the value 11.30 measured using microwave frequencies of 8.95 GHz on powder sample. 6 The polarized zero frequency dielectric constants obtained parallel to the a, b, and c axes of the crystal are 8.83, 9.79, and 9.01, respectively. These results clearly indicate the anisotropy in the optical properties of SnI 2 .…”

Section: Results From Optical Propertiesmentioning

confidence: 95%

“…5 Desai, Rai, and Vyas measured the bulk dielectric constant of SnI 2 as a function of temperature to understand the electric field distribution. 6 Fujita et al 7,8 have recently studied the polarized absorption and reflection spectra of SnI 2 at a lower temperature and they have found a direct transition at 2.57 eV. The Sn 2ϩ ions occupy two inequivalent sites in the monoclinic lattice.…”

Section: Introductionmentioning

confidence: 99%

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Optical properties of monoclinic SnI2from relativistic first-principles theory

et al. 1997

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Within the local-density approximation, using the relativistic full-potential linear muffin-tin orbital method, the electronic structure is calculated for the anisotropic, layered material SnI 2. The direct interband transitions are calculated using the full electric-dipole matrix elements between the Kohn-Sham eigenvalues in the ground state of the system. The inclusion of spin-orbit coupling was found to change the optical properties of this material considerably. Polarized absorption and reflection spectra are calculated and compared with recent experimental results. The experimentally suggested cationic excitation for the lowest-energy transition is confirmed. From the site and angular momentum decomposed electronic structure studies and the detailed analysis of the optical spectra it is found that the lowest-energy transition is taking place between Sn 5s ͑atom type 2a͒ → Sn 5p ͑atom type 4i͒ states. The ground state calculation was repeated using the tight-binding linear muffin-tin orbital-atomic sphere approximation method, and the resulting band structure agrees very well with the one calculated with the full-potential method. In contrast to recent experimental expectations, our calculations show an indirect band gap, which is in agreement with earlier semiempirical tight-binding calculations as well as with absorption and reflection spectra. ͓S0163-1829͑97͒02532-0͔

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Section: Results From Optical Propertiesmentioning

confidence: 95%

Section: Introductionmentioning

confidence: 99%

Optical properties of monoclinic SnI2from relativistic first-principles theory

et al. 1997

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“…2D HOP are known to present a strong exciton binding energy 21 related to abrupt dielectric interfaces 22 and exhibit a quantum confinement of type I 23,24 with a dielectric confinement 22,25 attributed to the contrast between the low dielectric constant of the organic part 26 and the high dielectric constant of the inorganic part. 27 On the other hand, 3D HOP show an exciton screened by polar vibrational modes and disordered configurations of polar organic cations. [28][29][30][31] The acquired control over the shape of the active materials allows one to tune quantum and dielectric confinements.…”

Section: Introductionmentioning

confidence: 99%

Quantum confinement and dielectric profiles of colloidal nanoplatelets of halide inorganic and hybrid organic–inorganic perovskites

et al. 2016

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Quantum confinement as well as high frequency ε∞ and static εs dielectric profiles are described for nanoplatelets of halide inorganic perovskites CsPbX3 (X = I, Br, Cl) and hybrid organic-inorganic perovskites (HOP) in two-dimensional (2D) and three-dimensional (3D) structures. 3D HOP are currently being sought for their impressive photovoltaic ability. Prior to this sudden popularity, 2D HOP materials were driving intense activity in the field of optoelectronics. Such developments have been enriched by the recent ability to synthesize colloidal nanostructures of controlled sizes of 2D and 3D HOP. This raises the need to achieve a thorough description of the electronic structure and dielectric properties of these systems. In this work, we go beyond the abrupt dielectric interface model and reach the atomic scale description. We examine the influence of the nature of the halogen and of the cation on the band structure and dielectric constants. Similarly, we survey the effect of dimensionality and shape of the perovskite. In agreement with recent experimental results, we show an increase of the band gap and a decrease of ε∞ when the size of a nanoplatelet reduces. By inspecting 2D HOP, we find that it cannot be described as a simple superposition of independent inorganic and organic layers. Finally, the dramatic impact of ionic contributions on the dielectric constant εs is analysed.

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“…[13,14] This excitonic binding energy causes dielectric confinement at the interfaces, which leads toward a contrast of dielectric constant values among the organic and inorganic parts. [15,16] Moreover, this confinement tunes the phonon modes greatly affecting the architecture of the materials interface, [17][18][19] In addition, the surface functionalization of inorganic material influences the architecture and dielectric confinement across the interface. This factor controls directly the excitonic behavior and the charge transfer across the interface.…”

Section: Introductionmentioning

confidence: 99%

Understanding the Heterointerfaces in Perovskite Solar Cells via Hole Selective Layer Surface Functionalization

Nath,

Behera,

Kumar

et al. 2023

Advanced Materials

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Interfaces in perovskite solar cells (PSCs) play a pivotal role in determining device performance by influencing charge transport and recombination. Understanding the physical processes at these interfaces is essential for achieving high‐power conversion efficiency in PSCs. Particularly, the interfaces involving oxide‐based transport layers are susceptible to defects like dangling bonds, excess oxygen, or oxygen deficiency. To address this issue, the surface of NiOx is passivated using octadecylphosphonic acid (ODPA), resulting in improved charge transport across the perovskite hole transport layer (HTL) interface. This surface treatment has led to the development of hysteresis‐free devices with an impressive ≈13% increase in power conversion efficiency. Computational studies have explored the halide perovskite architecture of ODPA‐treated HTL/Perovskite, aiming to unlock superior photovoltaic performance. The ODPA surface functionalization has demonstrated enhanced device performance, characterized by superior charge exchange capacity. Moreover, higher band‐to‐band recombination in photoluminescence and electroluminescence indicates presence of lower mid‐gap energy states, thereby increasing the effective photogenerated carrier density. These findings are expected to promote the utilization of various phosphonic acid‐based self‐assembly monolayers for surface passivation of oxide‐based transport layers in perovskite solar cells. Ultimately, this research contributes to the realization of efficient halide PSCs by harnessing the favorable architecture of NiOx interfaces.

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Microwave measurements of dielectric constants of Snl2 and Snl4

Cited by 8 publications

References 7 publications

Optical properties of monoclinic SnI2from relativistic first-principles theory

Optical properties of monoclinic SnI2from relativistic first-principles theory

Quantum confinement and dielectric profiles of colloidal nanoplatelets of halide inorganic and hybrid organic–inorganic perovskites

Understanding the Heterointerfaces in Perovskite Solar Cells via Hole Selective Layer Surface Functionalization

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