Dataset Information

Pressure-Induced Structural Evolution and Bandgap Optimization of Lead-Free Halide Double Perovskite (NH4)2SeBr6.

ABSTRACT: Lead-free halide double perovskites (HDPs) are promising candidates for high-performance solar cells because of their environmentally-friendly property and chemical stability in air. The power conversion efficiency of HDPs-based solar cells needs to be further improved before their commercialization in the market. It requires a thoughtful understanding of the correlation between their specific structure and property. Here, the structural and optical properties of an important HDP-based (NH4)2SeBr6 are investigated under high pressure. A dramatic piezochromism is found with the increase in pressure. Optical absorption spectra reveal the pressure-induced red-shift in bandgap with two distinct anomalies at 6.57 and 11.18 GPa, and the energy tunability reaches 360 meV within 20.02 GPa. Combined with structural characterizations, Raman and infrared spectra, and theoretical calculations using density functional theory, results reveal that, the first anomaly is caused by the formation of a Br-Br bond among the [SeBr6]2- octahedra, and the latter is attributed to a cubic-to-tetragonal phase transition. These results provide a clear correlation between the chemical bonding and optical properties of (NH4)2SeBr6. It is believed that the proposed strategy paves the way to optimize the optoelectronic properties of HDPs and further stimulate the development of next-generation clear energy based on HDPs solar cells.

SUBMITTER: Wang L

PROVIDER: S-EPMC7080510 | biostudies-literature | 2020 Mar

REPOSITORIES: biostudies-literature

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Publications

Pressure-Induced Structural Evolution and Bandgap Optimization of Lead-Free Halide Double Perovskite (NH4)2SeBr6.

Wang Lingrui L Yao Panpan P Wang Fei F Li Shunfang S Chen Yaping Y Xia Tianyu T Guo Erjia E Wang Kai K Zou Bo B Guo Haizhong H

Advanced science (Weinheim, Baden-Wurttemberg, Germany) 20200127 6

Lead-free halide double perovskites (HDPs) are promising candidates for high-performance solar cells because of their environmentally-friendly property and chemical stability in air. The power conversion efficiency of HDPs-based solar cells needs to be further improved before their commercialization in the market. It requires a thoughtful understanding of the correlation between their specific structure and property. Here, the structural and optical properties of an important HDP-based (NH4 ...[more]

PMID: 32195097

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Project description:Recently, lead halide perovskites have gained considerable attention by dint of their predominant physiochemical features and potential use in various applications with an improved power conversion efficiency. Despite the incredible technological and research breakthroughs in this field, most of those compounds present an obstacle to future commercialization due to their instability and extreme poisonousness. Because of this, it is preferable to replace lead with alternative stable elements to produce eco-friendly perovskites with equivalent optoelectronic qualities similar to lead-based perovskites. However, Pb-free perovskite-based devices have relatively low power conversion efficiency. Pressure might be considered an effective way for modifying the physical characteristics of these materials to enhance their performance and reveal structure-property correlations. The present study has been done to investigate the structural, electronic, optical, elastic, mechanical, and thermodynamic properties of nontoxic perovskite CsMgI3 under hydrostatic pressure by using density functional theory (DFT). At ambient pressure, the present findings are in excellent agreement with the available experimental data. Pressure causes the Mg-I and Cs-I bonds to shorten and become stronger. The absorption coefficient in the visible and ultraviolet (UV) zones grows up with the increase in pressure. Additionally, we have observed low reflectivity, a high-intensity conductivity peak, and a dielectric constant in the visible region of the electromagnetic spectrum. As pressure rises, the band gap keeps narrowing, facilitating an electron from the valence band to get excited easily at the conduction band. Furthermore, we analyze the mechanical, elastic, and thermodynamic properties under pressure, which suggests that this compound exhibit ductile behavior. The shrunk band gap and improved physical properties of CsMgI3 under hydrostatic pressure suggest that this material may be used in solar cells (for photovoltaic applications) and optoelectronic devices more frequently than at ambient pressure. In addition, this paper emphasizes the feasibility of hydrostatic pressure in the systematic modification of the optoelectronic and mechanical characteristics of lead-free halide perovskites.

Dataset Information

Pressure-Induced Structural Evolution and Bandgap Optimization of Lead-Free Halide Double Perovskite (NH4)2SeBr6.

Publications

Pressure-Induced Structural Evolution and Bandgap Optimization of Lead-Free Halide Double Perovskite (NH<sub>4</sub>)<sub>2</sub>SeBr<sub>6</sub>.

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