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Pols M, van Duin ACT, Calero S, Tao S. Mixing I and Br in Inorganic Perovskites: Atomistic Insights from Reactive Molecular Dynamics Simulations. THE JOURNAL OF PHYSICAL CHEMISTRY. C, NANOMATERIALS AND INTERFACES 2024; 128:4111-4118. [PMID: 38476824 PMCID: PMC10926166 DOI: 10.1021/acs.jpcc.4c00563] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 01/26/2024] [Revised: 02/06/2024] [Accepted: 02/08/2024] [Indexed: 03/14/2024]
Abstract
All-inorganic halide perovskites have received a great deal of attention as attractive alternatives to overcome the stability issues of hybrid halide perovskites that are commonly associated with organic cations. To find a compromise between the optoelectronic properties of CsPbI3 and CsPbBr3, perovskites with CsPb(BrxI1-x)3 mixed compositions are commonly used. An additional benefit is that without sacrificing the optoelectronic properties for applications such as solar cells or light-emitting diodes, small amounts of Br in CsPbI3 can prevent the inorganic perovskite from degrading to a photo-inactive non-perovskite yellow phase. Despite indications that strain in the perovskite lattice plays a role in the stabilization of the material, a full understanding of such strain is lacking. Here, we develop a reactive force field (ReaxFF) for perovskites starting from our previous work for CsPbI3, and we extend this force field to CsPbBr3 and mixed CsPb(BrxI1-x)3 compounds. This force field is used in large-scale molecular dynamics simulations to study perovskite phase transitions and the internal ion dynamics associated with the phase transitions. We find that an increase of the Br content lowers the temperature at which the perovskite reaches a cubic structure. Specifically, by substituting Br for I, the smaller ionic radius of Br induces a strain in the lattice that changes the internal dynamics of the octahedra. Importantly, this effect propagates through the perovskite lattice ranging up to distances of 2 nm, explaining why small concentrations of Br in CsPb(BrxI1-x)3 (x ≤ 1/4) have a significant impact on the phase stability of mixed halide perovskites.
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Affiliation(s)
- Mike Pols
- Materials
Simulation & Modelling, Department of Applied Physics and Science
Education, Eindhoven University of Technology, 5600 MB Eindhoven, The Netherlands
- Center
for Computational Energy Research, Department of Applied Physics and
Science Education, Eindhoven University
of Technology, 5600 MB Eindhoven, The Netherlands
| | - Adri C. T. van Duin
- Department
of Mechanical Engineering, Pennsylvania
State University, University
Park, Pennsylvania 16802, United States
| | - Sofía Calero
- Materials
Simulation & Modelling, Department of Applied Physics and Science
Education, Eindhoven University of Technology, 5600 MB Eindhoven, The Netherlands
| | - Shuxia Tao
- Materials
Simulation & Modelling, Department of Applied Physics and Science
Education, Eindhoven University of Technology, 5600 MB Eindhoven, The Netherlands
- Center
for Computational Energy Research, Department of Applied Physics and
Science Education, Eindhoven University
of Technology, 5600 MB Eindhoven, The Netherlands
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Wang N, Wu Y. First-Principles Investigation into the Interaction of H 2O with α-CsPbI 3 and the Intrinsic Defects within It. MATERIALS (BASEL, SWITZERLAND) 2024; 17:1091. [PMID: 38473563 DOI: 10.3390/ma17051091] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/20/2023] [Revised: 02/03/2024] [Accepted: 02/05/2024] [Indexed: 03/14/2024]
Abstract
CsPbI3 possesses three photoactive black phases (α, β, and γ) with perovskite structures and a non-photoactive yellow phase (δ) without a perovskite structure. Among these, α-CsPbI3 exhibits the best performance. However, it only exists at high temperatures and it tends to transform into the δ phase at room temperature, especially in humid environments. Therefore, the phase stability of CsPbI3, especially in humid environments, is the main obstacle to its further development. In this study, we studied the interaction of H2O with α-CsPbI3 and the intrinsic defects within it. It was found that the adsorption energy in the bulk is higher than that on the surface (-1.26 eV in the bulk in comparison with -0.60 eV on the surface); thus, H2O is expected to have a tendency to diffuse into the bulk once it adsorbs on the surface. Moreover, the intrinsic vacancy of VPb0 in the bulk phase can greatly promote H2O insertion due to the rearrangement of two I atoms in the two PbI6 octahedrons nearest to VPb0 and the resultant breaking of the Pb-I bond, which could promote the phase transition of α-CsPbI3 in a humid environment. Moreover, H2O adsorption onto VI+1 contributes to a further distortion in the vicinity of VI+1, which is expected to enhance the effect of VI+1 on the phase transition of α-CsPbI3. Clarifying the interaction of H2O with α-CsPbI3 and the intrinsic defects within it may provide guidance for further improvements in the stability of α-CsPbI3, especially in humid environments.
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Affiliation(s)
- Na Wang
- Department of Physical Chemistry, University of Science and Technology Beijing, Beijing 100083, China
- School of Metallurgical and Ecological Engineering, University of Science and Technology, Beijing 100083, China
| | - Yaqiong Wu
- Department of Physical Chemistry, University of Science and Technology Beijing, Beijing 100083, China
- School of Metallurgical and Ecological Engineering, University of Science and Technology, Beijing 100083, China
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Liang Y, Li F, Cui X, Lv T, Stampfl C, Ringer SP, Yang X, Huang J, Zheng R. Toward stabilization of formamidinium lead iodide perovskites by defect control and composition engineering. Nat Commun 2024; 15:1707. [PMID: 38402258 PMCID: PMC10894298 DOI: 10.1038/s41467-024-46044-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2023] [Accepted: 02/08/2024] [Indexed: 02/26/2024] Open
Abstract
Phase instability poses a serious challenge to the commercialization of formamidinium lead iodide (FAPbI3)-based solar cells and optoelectronic devices. Here, we combine density functional theory and machine learning molecular dynamics simulations, to investigate the mechanism driving the undesired α-δ phase transition of FAPbI3. Prevalent iodine vacancies and interstitials can significantly expedite the structural transition kinetics by inducing robust covalency during transition states. Extrinsically, the detrimental roles of atmospheric moisture and oxygen in degrading the FAPbI3 perovskite phase are also rationalized. Significantly, we discover the compositional design principles by categorizing that A-site engineering primarily governs thermodynamics, whereas B-site doping can effectively manipulate the kinetics of the phase transition in FAPbI3, highlighting lanthanide ions as promising B-site substitutes. A-B mixed doping emerges as an efficient strategy to synergistically stabilize α-FAPbI3, as experimentally demonstrated by substantially higher initial optoelectronic characteristics and significantly enhanced phase stability in Cs-Eu doped FAPbI3 as compared to its Cs-doped counterpart. This study provides scientific guidance for the design and optimization of long-term stable FAPbI3-based solar cells and other optoelectronic devices through defect control and synergetic composition engineering.
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Affiliation(s)
- Yuhang Liang
- School of Chemical and Biomolecular Engineering, The University of Sydney, Sydney, NSW 2006, Australia.
- School of Physics, The University of Sydney, Sydney, NSW, 2006, Australia.
| | - Feng Li
- School of Physics, The University of Sydney, Sydney, NSW, 2006, Australia.
| | - Xiangyuan Cui
- School of Aerospace, Mechanical and Mechatronic Engineering, The University of Sydney, Sydney, NSW, 2006, Australia.
| | - Taoyuze Lv
- School of Physics, The University of Sydney, Sydney, NSW, 2006, Australia
| | - Catherine Stampfl
- School of Physics, The University of Sydney, Sydney, NSW, 2006, Australia
| | - Simon P Ringer
- School of Aerospace, Mechanical and Mechatronic Engineering, The University of Sydney, Sydney, NSW, 2006, Australia
| | - Xudong Yang
- State Key Laboratory of Metal Matrix Composites, Shanghai Jiao Tong University, Shanghai, 200240, China
- Center of Hydrogen Science, School of Materials Science and Engineering, Shanghai Jiao Tong University, Shanghai, 200240, China
- Zhangjiang Institute for Advanced Study, Shanghai Jiao Tong University, Shanghai, 201210, China
| | - Jun Huang
- School of Chemical and Biomolecular Engineering, The University of Sydney, Sydney, NSW 2006, Australia.
| | - Rongkun Zheng
- School of Physics, The University of Sydney, Sydney, NSW, 2006, Australia.
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