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Pecoraro A, Muñoz-García AB, Sannino GV, Veneri PD, Pavone M. Exotic hexagonal NaCl atom-thin layer on methylammonium lead iodide perovskite: new hints for perovskite solar cells from first-principles calculations. Phys Chem Chem Phys 2024; 26:1602-1607. [PMID: 38165025 DOI: 10.1039/d3cp02712k] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2024]
Abstract
Alkali halides are simple inorganic compounds extensively used as surface modifiers in optoelectronic devices. In perovskite solar cells (PSCs), they act as interlayers between the light absorber material and the charge selective layers improving their contact quality. They introduce surface dipoles that enable the fine tuning of the relative band alignment and passivate surface defects, a well-known drawback of hybrid organic-inorganic perovskites, that is responsible for most of the issues hampering the long-term performances. Reducing the thickness of such salt-based insulating layer might be beneficial in terms of charge transfer between the perovskite and the electron/hole transport layers. In this context, here we apply density functional theory (DFT) to characterize the structure and the electronic features of atom-thin layers of NaCl adsorbed on the methylammonium lead iodide (MAPI) perovskite. We analyze two different models of MAPI surface terminations and find unexpected structural reconstructions arising at the interface. Unexpectedly, we find an exotic honeycomb-like structuring of the salt, also recently observed in experiments on a diamond substrate. We also investigate how the salt affects the perovskite electronic properties that are key to control the charge dynamics at the interface. Moreover, we also assess the salt ability to improve the defect tolerance of the perovskite surface. With these results, we derive new hints regarding the potential benefits of using an atom-thin layer of alkali halides in PSCs.
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Affiliation(s)
- Adriana Pecoraro
- Department of Physics "E. Pancini", University of Naples Federico II, Napoli, Italy.
- INSTM-GISEL, National Interuniversity Consortium of Materials Science and Technology (INSTM), Florence, Italy.
| | - Ana B Muñoz-García
- Department of Physics "E. Pancini", University of Naples Federico II, Napoli, Italy.
- INSTM-GISEL, National Interuniversity Consortium of Materials Science and Technology (INSTM), Florence, Italy.
| | - Gennaro V Sannino
- Department of Chemical Sciences, University of Naples Federico II, Napoli, Italy
- Italian National Agency for New Technologies, Energy and Sustainable Economic Development (ENEA), Portici (NA), Italy
| | - Paola Delli Veneri
- Italian National Agency for New Technologies, Energy and Sustainable Economic Development (ENEA), Portici (NA), Italy
| | - Michele Pavone
- INSTM-GISEL, National Interuniversity Consortium of Materials Science and Technology (INSTM), Florence, Italy.
- Department of Chemical Sciences, University of Naples Federico II, Napoli, Italy
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2
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Wang Y, Crespi VH, Cohen ML, Nourhani A. Nonstoichiometric Salt Intercalation as a Means to Stabilize Alkali Doping of 2D Materials. PHYSICAL REVIEW LETTERS 2022; 129:266401. [PMID: 36608189 DOI: 10.1103/physrevlett.129.266401] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/01/2021] [Revised: 08/11/2022] [Accepted: 09/30/2022] [Indexed: 06/17/2023]
Abstract
Although doping with alkali atoms is a powerful technique for introducing charge carriers into physical systems, the resulting charge-transfer systems are generally not air stable. Here we describe computationally a strategy towards increasing the stability of alkali-doped materials that employs stoichiometrically unbalanced salt crystals with excess cations (which could be deposited during, e.g., in situ gating) to achieve doping levels similar to those attained by pure alkali metal doping. The crystalline interior of the salt crystal acts as a template to stabilize the excess dopant atoms against oxidation and deintercalation, which otherwise would be highly favorable. We characterize this doping method for graphene, NbSe_{2}, and Bi_{2}Se_{3} and its effect on direct-to-indirect band gap transitions, 2D superconductivity, and thermoelectric performance. Salt intercalation should be generally applicable to systems which can accommodate this "ionic crystal" doping (and particularly favorable when geometrical packing constraints favor nonstoichiometry).
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Affiliation(s)
- Yuanxi Wang
- 2-Dimensional Crystal Consortium, Materials Research Institute, The Pennsylvania State University, University Park, Pennsylvania 16802, USA
- Department of Physics, University of North Texas, Denton, Texas 76201, USA
| | - Vincent H Crespi
- 2-Dimensional Crystal Consortium, Materials Research Institute, The Pennsylvania State University, University Park, Pennsylvania 16802, USA
- Department of Physics, The Pennsylvania State University, University Park, Pennsylvania 16802, USA
| | - Marvin L Cohen
- Department of Physics, University of California at Berkeley, Berkeley, California 94720, USA
- Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
| | - Amir Nourhani
- Department of Mechanical Engineering, University of Akron, Akron, Ohio 44325, USA
- Biomimicry Research and Innovation Center, University of Akron, Akron, Ohio 44325, USA
- Departments of Biology, Mathematics, and Chemical, Biomolecular, and Corrosion Engineering, University of Akron, Akron, Ohio 44325, USA
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Zhao Y, Zhang Q, Li Y, Chen L, Yi R, Peng B, Nie D, Zhang L, Shi G, Zhang S, Zhang L. Graphitic-like Hexagonal Phase of Alkali Halides in Quasi-Two-Dimensional Confined Space under Ambient Conditions. ACS NANO 2022; 16:2046-2053. [PMID: 35137582 DOI: 10.1021/acsnano.1c07424] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
The discovery of specific matter phases with abnormal physical properties in low-dimensional systems and/or on particular substrates, such as the hexagonal phase of ice and two-dimensional (2D) CaCl with an abnormal valence state, continuously reveals more fundamental mechanisms of the nature. Alkali halides, represented by NaCl, are one of the most common compounds and usually thought to be well-understood. In the past decades, many theoretical studies suggested the existence of one particular phase, that is, the graphitic-like hexagonal phase of alkali halides at high pressure or in low-dimension states, with the expectation of improved properties of this matter phase but lacking experimental evidence due to severe technical challenges. Here, by optimized cryo-electron microscopy, we report the direct atomic-resolution observation and in situ characterization of the prevalent and stable graphitic-like alkali halide hexagonal phases, which were spontaneously formed by unsaturated NaCl and LiCl solution, respectively, in the quasi-2D confined space between reduced graphene oxide layers under ambient conditions. Combined with a control experiment, density functional theory calculations, and previous theoretical studies, we believe that a delicate balance among the cation-π interaction of the solute and substrate, electrostatic interactions of anions and cations, solute-solvent interactions, and thermodynamics under confinement synergistically results in the formation of such hexagonal crystalline phases. These findings highlight the effects of the substrate and the confined space on the formation of specific matter phases and provide a universal scheme for the preparation of special graphitic-like hexagonal phases of alkali halides.
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Affiliation(s)
- Yimin Zhao
- MOE Key Laboratory for Nonequilibrium Synthesis and Modulation of Condensed Matter, School of Physics, Xi'an Jiaotong University, Xi'an 710049, China
| | - Quan Zhang
- MOE Key Laboratory for Nonequilibrium Synthesis and Modulation of Condensed Matter, School of Physics, Xi'an Jiaotong University, Xi'an 710049, China
| | - Yunzhang Li
- Shanghai Applied Radiation Institute, Shanghai University, Shanghai 200444, China
| | - Liang Chen
- School of Physical Science and Technology, Ningbo University, Ningbo 315211, China
- Department of Optical Engineering, Zhejiang Prov Key Lab Carbon Cycling Forest Ecosy, Zhejiang Prov Key Lab of Chemical Utilization of Forestry Biomass, Zhejiang A&F University, Lin'an 311300, China
| | - Ruobing Yi
- MOE Key Laboratory for Nonequilibrium Synthesis and Modulation of Condensed Matter, School of Physics, Xi'an Jiaotong University, Xi'an 710049, China
- Department of Optical Engineering, Zhejiang Prov Key Lab Carbon Cycling Forest Ecosy, Zhejiang Prov Key Lab of Chemical Utilization of Forestry Biomass, Zhejiang A&F University, Lin'an 311300, China
| | - Bingquan Peng
- MOE Key Laboratory for Nonequilibrium Synthesis and Modulation of Condensed Matter, School of Physics, Xi'an Jiaotong University, Xi'an 710049, China
| | - Dexi Nie
- MOE Key Laboratory for Nonequilibrium Synthesis and Modulation of Condensed Matter, School of Physics, Xi'an Jiaotong University, Xi'an 710049, China
| | - Lihao Zhang
- MOE Key Laboratory for Nonequilibrium Synthesis and Modulation of Condensed Matter, School of Physics, Xi'an Jiaotong University, Xi'an 710049, China
| | - Guosheng Shi
- Shanghai Applied Radiation Institute, Shanghai University, Shanghai 200444, China
| | - Shengli Zhang
- MOE Key Laboratory for Nonequilibrium Synthesis and Modulation of Condensed Matter, School of Physics, Xi'an Jiaotong University, Xi'an 710049, China
| | - Lei Zhang
- MOE Key Laboratory for Nonequilibrium Synthesis and Modulation of Condensed Matter, School of Physics, Xi'an Jiaotong University, Xi'an 710049, China
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Wang L, Chen J, Cox SJ, Liu L, Sosso GC, Li N, Gao P, Michaelides A, Wang E, Bai X. Microscopic Kinetics Pathway of Salt Crystallization in Graphene Nanocapillaries. PHYSICAL REVIEW LETTERS 2021; 126:136001. [PMID: 33861106 DOI: 10.1103/physrevlett.126.136001] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/29/2020] [Revised: 02/08/2021] [Accepted: 02/26/2021] [Indexed: 06/12/2023]
Abstract
The fundamental understanding of crystallization, in terms of microscopic kinetic and thermodynamic details, remains a key challenge in the physical sciences. Here, by using in situ graphene liquid cell transmission electron microscopy, we reveal the atomistic mechanism of NaCl crystallization from solutions confined within graphene cells. We find that rock salt NaCl forms with a peculiar hexagonal morphology. We also see the emergence of a transitory graphitelike phase, which may act as an intermediate in a two-step pathway. With the aid of density functional theory calculations, we propose that these observations result from a delicate balance between the substrate-solute interaction and thermodynamics under confinement. Our results highlight the impact of confinement on both the kinetics and thermodynamics of crystallization, offering new insights into heterogeneous crystallization theory and a potential avenue for materials design.
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Affiliation(s)
- Lifen Wang
- Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
- Songshan Lake Laboratory for Materials Science, Dongguan 523000, China
| | - Ji Chen
- School of Physics and the Collaborative Innovation Center of Quantum Matters, Peking University, Beijing 100871, China
| | - Stephen J Cox
- Yusuf Hamied Department of Chemistry, University of Cambridge, Lensfield Road, Cambridge CB2 1EW, United Kingdom
| | - Lei Liu
- School of Materials Science and Engineering, Peking University, Beijing 100871, China
| | - Gabriele C Sosso
- Department of Chemistry and Centre for Scientific Computing, University of Warwick, Coventry CV4 7AL, United Kingdom
| | - Ning Li
- International Center for Quantum Materials, School of Physics, Peking University, Beijing 100871, China
- Electron Microscopy Laboratory, School of Physics, Peking University, Beijing 100871, China
| | - Peng Gao
- International Center for Quantum Materials, School of Physics, Peking University, Beijing 100871, China
- Electron Microscopy Laboratory, School of Physics, Peking University, Beijing 100871, China
| | - Angelos Michaelides
- Yusuf Hamied Department of Chemistry, University of Cambridge, Lensfield Road, Cambridge CB2 1EW, United Kingdom
- Department of Physics and Astronomy, and Thomas Young Centre, University College London, London WC1E 6BT, United Kingdom
- London Centre for Nanotechnology, University College London, London WC1H 0AH, United Kingdom
| | - Enge Wang
- Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
- Songshan Lake Laboratory for Materials Science, Dongguan 523000, China
- International Center for Quantum Materials, School of Physics, Peking University, Beijing 100871, China
- School of Physics, Liaoning University, Shenyang 110036, China
- Interdisciplinary Institute of Light-Element Quantum Materials and Research Center for Light-Element Advanced Materials, Peking University, Beijing 100871, China
| | - Xuedong Bai
- Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
- Songshan Lake Laboratory for Materials Science, Dongguan 523000, China
- School of Physical Sciences, University of Chinese Academy of Sciences, Beijing 100190, China
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5
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Tikhomirova KA, Tantardini C, Sukhanova EV, Popov ZI, Evlashin SA, Tarkhov MA, Zhdanov VL, Dudin AA, Oganov AR, Kvashnin DG, Kvashnin AG. Exotic Two-Dimensional Structure: The First Case of Hexagonal NaCl. J Phys Chem Lett 2020; 11:3821-3827. [PMID: 32330050 DOI: 10.1021/acs.jpclett.0c00874] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
NaCl is one of the simplest compounds and was thought to be well-understood, and yet, unexpected complexities related to it were uncovered at high pressure and in low-dimensional states. Here, exotic hexagonal NaCl thin films on the (110) diamond surface were crystallized in the experiment following a theoretical prediction based on ab initio evolutionary algorithm USPEX. State-of-the-art calculations and experiments showed the existence of a hexagonal NaCl thin film, which is due to the strong chemical interaction of the NaCl film with the diamond substrate.
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Affiliation(s)
- Kseniya A Tikhomirova
- Skolkovo Institute of Science and Technology, 30, bld. 1 Bolshoy Boulevard, Moscow 121205, Russia
| | - Christian Tantardini
- Skolkovo Institute of Science and Technology, 30, bld. 1 Bolshoy Boulevard, Moscow 121205, Russia
| | - Ekaterina V Sukhanova
- Emanuel Institute of Biochemical Physics RAS, 4 Kosigina Street, Moscow 119334, Russia
- Moscow Institute of Physics and Technology, 9 Institutsky Pereulok, Dolgoprudny 141700, Russia
| | - Zakhar I Popov
- Emanuel Institute of Biochemical Physics RAS, 4 Kosigina Street, Moscow 119334, Russia
| | - Stanislav A Evlashin
- Skolkovo Institute of Science and Technology, 30, bld. 1 Bolshoy Boulevard, Moscow 121205, Russia
| | - Mikhail A Tarkhov
- Institute of Nanotechnologies of Microelectronics of the Russian Academy of Sciences, 32 A Leninsky Prospekt, Moscow 119991, Russia
| | | | - Alexander A Dudin
- Institute of Nanotechnologies of Microelectronics of the Russian Academy of Sciences, 32 A Leninsky Prospekt, Moscow 119991, Russia
| | - Artem R Oganov
- Skolkovo Institute of Science and Technology, 30, bld. 1 Bolshoy Boulevard, Moscow 121205, Russia
- Moscow Institute of Physics and Technology, 9 Institutsky Pereulok, Dolgoprudny 141700, Russia
- International Center for Materials Discovery, Northwestern Polytechnical University, Xi'an 710072, China
| | - Dmitry G Kvashnin
- Emanuel Institute of Biochemical Physics RAS, 4 Kosigina Street, Moscow 119334, Russia
- Moscow Institute of Physics and Technology, 9 Institutsky Pereulok, Dolgoprudny 141700, Russia
| | - Alexander G Kvashnin
- Skolkovo Institute of Science and Technology, 30, bld. 1 Bolshoy Boulevard, Moscow 121205, Russia
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6
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Kvashnin AG, Kvashnin DG, Oganov AR. Novel Unexpected Reconstructions of (100) and (111) Surfaces of NaCl: Theoretical Prediction. Sci Rep 2019; 9:14267. [PMID: 31582761 PMCID: PMC6776646 DOI: 10.1038/s41598-019-50548-8] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2019] [Accepted: 09/12/2019] [Indexed: 11/09/2022] Open
Abstract
We have predicted stable reconstructions of the (100) and (111) surfaces of NaCl using the global optimization algorithm USPEX. Several new reconstructions, together with the previously reported ones, are found. For the cleaved bare (100) surface, pure Na and pure Cl are the only stable surface phases. Our study of the (111) surface shows that a newly predicted Na3Cl-(1 × 1) reconstruction is thermodynamically stable in a wide range of chlorine chemical potentials. It has a sawtooth-like profile where each facet reproduces the (100) surface of rock-salt NaCl, hinting on the preferred growth of the (100) surface. We used Bader charge analysis to explain the preferable formation of this sawtooth-like Na3Cl-(1 × 1) reconstruction of the (111) surface of NaCl. We find that at a very high chemical potential of Na, the polar (and normally absent) (111) surface becomes part of the equilibrium crystal morphology. At both very high and very low chemical potentials of Cl, we predict a large decrease of surface energy and fracture toughness (the Rehbinder effect).
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Affiliation(s)
- Alexander G Kvashnin
- Skolkovo Institute of Science and Technology, Skolkovo Innovation Center, 3 Nobel Street, Moscow, 121205, Russia.,Moscow Institute of Physics and Technology, 9 Institutsky Pereulok, Dolgoprudny, 141700, Russia
| | - Dmitry G Kvashnin
- Emanuel Institute of Biochemical Physics RAS, 4 Kosigina Street, Moscow, 119334, Russia. .,National University of Science and Technology MISIS, 4 Leninskiy Prospekt, Moscow, 119049, Russia.
| | - Artem R Oganov
- Skolkovo Institute of Science and Technology, Skolkovo Innovation Center, 3 Nobel Street, Moscow, 121205, Russia.,Moscow Institute of Physics and Technology, 9 Institutsky Pereulok, Dolgoprudny, 141700, Russia.,International Center for Materials Discovery, Northwestern Polytechnical University, Xi'an, 710072, China
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7
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Kvashnin DG, Kvashnina OP, Avramov PV, Sorokin PB, Kvashnin AG. Novel hybrid C/BN two-dimensional heterostructures. NANOTECHNOLOGY 2017; 28:085205. [PMID: 28114121 DOI: 10.1088/1361-6528/aa55e9] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
Here we present an investigation of new quasi-two-dimensional heterostructures based on the alternation of bounded carbon and boron nitride layers (C/BN). We carried out a theoretical study of the atomic structure, stability and electronic properties of the proposed heterostructures. Such ultrathin quasi-two-dimensional C/BN films can be synthesized by means of chemically induced phase transition by connection of the layers of multilayered h-BN/graphene van der Waals heterostructures, which is indicated by the negative phase transition pressure in the calculated phase diagrams (P, T) of the films. It was shown that the band gap value of the C/BN films spans the infrared and visible spectrum. We hope that the proposed films and fabrication method can be considered as a possible route to obtain nanostructures with a controllable band gap in wide energy range. This makes these materials potentially suitable for a variety of applications, including photovoltaics, photoelectronics and more.
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Affiliation(s)
- Dmitry G Kvashnin
- Emanuel Institute of Biochemical Physics, Russian Academy of Science, 4 Kosigin Street, Moscow, 119334, Russian Federation. National University of Science and Technology MISiS, 4 Leninskiy Prospekt, Moscow, 119049, Russian Federation
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Kvashnin AG, Pashkin EY, Yakobson BI, Sorokin PB. Ionic Graphitization of Ultrathin Films of Ionic Compounds. J Phys Chem Lett 2016; 7:2659-2663. [PMID: 27333810 DOI: 10.1021/acs.jpclett.6b01214] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
On the basis of ab initio density functional calculations, we performed a comprehensive investigation of the general graphitization tendency in rocksalt-type structures. In this paper, we determine the critical slab thickness for a range of ionic cubic crystal systems, below which a spontaneous conversion from a cubic to a layered graphitic-like structure occurs. This conversion is driven by surface energy reduction. Using only fundamental parameters of the compounds such as the Allen electronegativity and ionic radius of the metal atom, we also develop an analytical relation to estimate the critical number of layers.
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Affiliation(s)
- A G Kvashnin
- Skolkovo Institute of Science and Technology (Skoltech), Skolkovo Innovation Center 143026, 3 Nobel Street, Moscow, Russian Federation
- Moscow Institute of Physics and Technology , 9 Institutsky lane, Dolgoprudny, 141700, Russian Federation
| | - E Y Pashkin
- Moscow Institute of Physics and Technology , 9 Institutsky lane, Dolgoprudny, 141700, Russian Federation
- Technological Institute for Superhard and Novel Carbon Materials , 7a Centralnaya Street, Troitsk, Moscow, 142190, Russian Federation
| | - B I Yakobson
- Department of Materials Science and NanoEngineering and the Smalley Institute for Nanoscale Science and Technology, Rice University , Houston, Texas 77005, United States
| | - P B Sorokin
- Technological Institute for Superhard and Novel Carbon Materials , 7a Centralnaya Street, Troitsk, Moscow, 142190, Russian Federation
- National University of Science and Technology MISiS , 4 Leninskiy Prospekt, Moscow, 119049, Russian Federation
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