1
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Pathak R, Dutta P, Dolui K, Vasdev A, Ghosh A, Roy RS, Gautam UK, Maji TK, Sheet G, Biswas K. Mild chemistry synthesis of ultrathin Bi 2O 2S nanosheets exhibiting 2D-ferroelectricity at room temperature. Chem Sci 2024; 15:7170-7177. [PMID: 38756816 PMCID: PMC11095514 DOI: 10.1039/d4sc00067f] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2024] [Accepted: 04/07/2024] [Indexed: 05/18/2024] Open
Abstract
Modern technology demands miniaturization of electronic components to build small, light, and portable devices. Hence, discovery and synthesis of new non-toxic, low cost, ultra-thin ferroelectric materials having potential applications in various electronic and optoelectronic devices are of paramount importance. However, achieving room-temperature ferroelectricity in two dimensional (2D) ultra-thin systems remains a major challenge as conventional three-dimensional ferroelectric materials lose their ferroelectricity when the thickness is brought down below a critical value owing to the depolarization field. Herein, we report room-temperature ferroelectricity in ultra-thin single-crystalline 2D nanosheets of Bi2O2S synthesized by a simple, rapid, and scalable solution-based soft chemistry method. The ferroelectric ground state of Bi2O2S nanosheets is confirmed by temperature-dependent dielectric measurements as well as piezoelectric force microscopy and spectroscopy. High resolution transmission electron microscopy analysis and density functional theory-based calculations suggest that the ferroelectricity in Bi2O2S nanosheets arises due to the local distortion of Bi2O2 layers, which destroys the local inversion symmetry of Bi2O2S.
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Affiliation(s)
- Riddhimoy Pathak
- New Chemistry Unit, International Centre for Materials Science, School of Advanced Materials, Jawaharlal Nehru Centre for Advanced Scientific Research (JNCASR) Jakkur P.O. Bangalore 560064 India
| | - Prabir Dutta
- New Chemistry Unit, International Centre for Materials Science, School of Advanced Materials, Jawaharlal Nehru Centre for Advanced Scientific Research (JNCASR) Jakkur P.O. Bangalore 560064 India
| | - Kapildeb Dolui
- Department of Materials Science & Metallurgy, University of Cambridge 27 Charles Babbage Road Cambridge CB3 0FS UK
| | - Aastha Vasdev
- Department of Physical Sciences, Indian Institute of Science Education and Research Mohali Sector 81, S. A. S. Nagar, Manauli, P.O. Box 140306 India
| | - Adrija Ghosh
- New Chemistry Unit, International Centre for Materials Science, School of Advanced Materials, Jawaharlal Nehru Centre for Advanced Scientific Research (JNCASR) Jakkur P.O. Bangalore 560064 India
| | - Raj Sekhar Roy
- Department of Chemical Sciences, Indian Institute of Science Education and Research Mohali Sector 81, S. A. S. Nagar, Manauli, P.O. Box 140306 India
| | - Ujjal K Gautam
- Department of Chemical Sciences, Indian Institute of Science Education and Research Mohali Sector 81, S. A. S. Nagar, Manauli, P.O. Box 140306 India
| | - Tapas Kumar Maji
- New Chemistry Unit, International Centre for Materials Science, School of Advanced Materials, Jawaharlal Nehru Centre for Advanced Scientific Research (JNCASR) Jakkur P.O. Bangalore 560064 India
- Chemistry and Physics of Materials Unit, Jawaharlal Nehru Centre for Advanced Scientific Research (JNCASR) Jakkur P.O. Bangalore 560064 India
| | - Goutam Sheet
- Department of Physical Sciences, Indian Institute of Science Education and Research Mohali Sector 81, S. A. S. Nagar, Manauli, P.O. Box 140306 India
| | - Kanishka Biswas
- New Chemistry Unit, International Centre for Materials Science, School of Advanced Materials, Jawaharlal Nehru Centre for Advanced Scientific Research (JNCASR) Jakkur P.O. Bangalore 560064 India
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2
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Han SW, Yun WS, Seong S, Tahir Z, Kim YS, Ko M, Ryu S, Bae JS, Ahn CW, Kang J. Hidden Direct Bandgap of Bi 2O 2Se by Se Vacancy and Enhanced Direct Bandgap of Bismuth Oxide Overlayer. J Phys Chem Lett 2024; 15:1590-1595. [PMID: 38306160 DOI: 10.1021/acs.jpclett.3c03223] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2024]
Abstract
The Bi2O2Se surfaces are well-known to possess 50% Se vacancies, yet they have shown no in-gap states within the indirect bandgap (∼0.8 eV). We have found that the hidden in-gap states arising from the Se vacancies in a 2 × 1 pattern induce a reduced direct bandgap (∼0.5 eV). Such a reduced direct bandgap is responsible for the high electron mobility of Bi2O2Se. Moreover, the Bi oxide overlayers of the Bi thin films, formed through air exposure and annealing, unexpectedly exhibit a large direct bandgap (∼2.1 eV). The simplified fabrication of Bi oxide overlayers provides promise for improving Bi2O2Se electronic devices and enhancing photocatalytic activity.
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Affiliation(s)
- Sang Wook Han
- Basic Science Research Institute and Energy Harvest Storage Research Center, University of Ulsan, Ulsan 44610, Republic of Korea
| | - Won Seok Yun
- Convergence Research Institute, DGIST, Daegu 42988, Republic of Korea
| | - Seungho Seong
- Department of Physics, The Catholic University of Korea, Bucheon 14662, Republic of Korea
| | - Zeeshan Tahir
- Department of Semiconductor Physics and Energy Harvest-Storage Research Center, University of Ulsan, Ulsan 44610, Republic of Korea
| | - Yong Soo Kim
- Department of Semiconductor Physics and Energy Harvest-Storage Research Center, University of Ulsan, Ulsan 44610, Republic of Korea
| | - Minji Ko
- Department of Chemistry, Pohang University of Science and Technology (POSTECH), Pohang, Gyeongbuk 37673, Republic of Korea
| | - Sunmin Ryu
- Department of Chemistry, Pohang University of Science and Technology (POSTECH), Pohang, Gyeongbuk 37673, Republic of Korea
| | - Jong-Seong Bae
- Busan Center, Korea Basic Science Institute, Busan 46742, Republic of Korea
| | - Chang Won Ahn
- Basic Science Research Institute and Energy Harvest Storage Research Center, University of Ulsan, Ulsan 44610, Republic of Korea
| | - Jeongsoo Kang
- Department of Physics, The Catholic University of Korea, Bucheon 14662, Republic of Korea
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3
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Butreddy P, Wijesingha M, Laws S, Pathiraja G, Mo Y, Rathnayake H. Insight into the Isoreticularity of Li-MOFs for the Design of Low-Density Solid and Quasi-Solid Electrolytes. CHEMISTRY OF MATERIALS : A PUBLICATION OF THE AMERICAN CHEMICAL SOCIETY 2023; 35:9857-9878. [PMID: 38107191 PMCID: PMC10720344 DOI: 10.1021/acs.chemmater.3c01021] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 05/02/2023] [Revised: 11/10/2023] [Accepted: 11/13/2023] [Indexed: 12/19/2023]
Abstract
Isoreticularity in metal organic frameworks (MOFs) allows the design of the framework structure and tailoring the pore aperture at the molecular level. The optimal pore volume, long-range order of framework expansion, and crystallite size (grain size) could enable improving Li-ion conduction, thereby providing a unique opportunity to design high-performance solid and quasi-solid electrolytes. However, definitive understanding of the pore aperture, framework expansion, and crystallite size on the Li-ion conduction and its mechanism in MOFs remains at the exploratory stage. Among the different MOF subfamilies, Li-MOFs created by the isoreticular framework expansion using dicarboxylates of benzene, naphthalene, and biphenyl building blocks emerge as low-density porous solids with exceptional thermal stability to study the solid-state Li+ transport mechanisms. Herein, we report the subtle effect of the isoreticularity in Li-MOFs on the performance of solid and quasi-solid-state Li+ conduction, providing new insight into Li+ transport mechanisms in MOFs for the first time. Our experimental and computational results show that the reticular design on an isostructural extended framework structure with the optimal pore aperture and crystallite size can influence the Li+ conductivity, exhibiting comparable ionic conductivities to solid polymer electrolytes at room temperature. Aligning with the computational studies, our experimental absorption spectral traces of solid electrolytes prepared by encapsulating lithium salt (LiClO4) and the plasticizer (ethylene carbonate) with Li-MOFs confirm the participation of the free and bound states of Li+ in a pore filling-driven ion conduction mechanism. We postulate that porous channels of Li-MOFs aid free Li+ to move through the pores via a vehicle-type mechanism, in which the pore-filled plasticizer acts as a carrier for mobile Li+ while the framework's functional sites transport the bound state of Li+ via an ion hopping mechanism from one crystallite site to another. Our computational studies performed on the Li+ conduction pathway validated the postulated pore filling mechanism and confirmed the involvement of bridging complexes, formed by binding Li+ onto the framework's functional sites as well as to the pore-filled ethylene carbonates. The Li+ diffusion energy barrier profiles along with the respective conformational changes during the diffusion of Li+ in solid electrolytes prepared from Li-BDC MOF and Li-NDC MOF strongly support the cooperative movement of Li+ ions via ion hopping along the framework's edges and vehicle-type transfer, involving the pore-filled plasticizer. Our findings suggest that cooperative function of the optimal pore volume, framework expansion, and crystallite size play a unique role in Li-ion conduction, thereby providing design guidelines for the low-density solid and quasi-solid electrolytes.
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Affiliation(s)
- Pravalika Butreddy
- Department of Nanoscience,
Joint School of Nanoscience & Nanoengineering, University of North Carolina at Greensboro, 1907 East Gate City Blvd, Greensboro, North Carolina 27401, United States
| | - Manoj Wijesingha
- Department of Nanoscience,
Joint School of Nanoscience & Nanoengineering, University of North Carolina at Greensboro, 1907 East Gate City Blvd, Greensboro, North Carolina 27401, United States
| | - Selina Laws
- Department of Nanoscience,
Joint School of Nanoscience & Nanoengineering, University of North Carolina at Greensboro, 1907 East Gate City Blvd, Greensboro, North Carolina 27401, United States
| | - Gayani Pathiraja
- Department of Nanoscience,
Joint School of Nanoscience & Nanoengineering, University of North Carolina at Greensboro, 1907 East Gate City Blvd, Greensboro, North Carolina 27401, United States
| | - Yirong Mo
- Department of Nanoscience,
Joint School of Nanoscience & Nanoengineering, University of North Carolina at Greensboro, 1907 East Gate City Blvd, Greensboro, North Carolina 27401, United States
| | - Hemali Rathnayake
- Department of Nanoscience,
Joint School of Nanoscience & Nanoengineering, University of North Carolina at Greensboro, 1907 East Gate City Blvd, Greensboro, North Carolina 27401, United States
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4
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Verma D, Chen TC, Liu B, Lai CS. Bi 2O 2Se-based CBRAM integrated artificial synapse. Heliyon 2023; 9:e22512. [PMID: 38107308 PMCID: PMC10724560 DOI: 10.1016/j.heliyon.2023.e22512] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2023] [Revised: 10/30/2023] [Accepted: 11/14/2023] [Indexed: 12/19/2023] Open
Abstract
Integrating two-dimensional (2D) semiconducting materials into memristor structures has paved the way for emerging 2D materials to be employed in a vast field of memory applications. Bismuth oxyselenide (Bi2O2Se), a 2D material with high electron mobility, has attracted significant research interest owing to its great potential in various fields of advanced applications. Here, we explore the out-of-plane intrinsic switching behavior of few-layered Bi2O2Se via a cross point device for application in conductive bridge random access memory (CBRAM) and artificial synapses for neuromorphic computing. Via state-of-the-art methods, CVD-grown Bi2O2Se nanoplate is applied as a switching material (SM) in an Al/Cu/Bi2O2Se/Pd CBRAM structure. The device exhibits ∼90 consecutive DC cycles with a tight distribution of the SET/RESET voltages under a compliance current (CC) of 1 mA, a retention of over 10 ks, and multilevel switching characteristics showing four distinct states at Vread values of 0.1, 0.2, 0.25, and 0.3 V. Moreover, an artificial synapse is realized with potentiation and depression by modulating the conductance. The switching mechanism is explained via Cu migration through Bi2O2Se based on HRTEM analysis. The present structure shows potential for future integrated memory applications.
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Affiliation(s)
- Dharmendra Verma
- Department of Electronic Engineering, Chang Gung University, Taoyuan 33302, Taiwan
| | - Tsung-Cheng Chen
- Department of Electronic Engineering, Chang Gung University, Taoyuan 33302, Taiwan
| | - Bo Liu
- Faculty of Information Technology, College of Microelectronics, Beijing University of Technology, Beijing 100124, People’s Republic of China
| | - Chao-Sung Lai
- Department of Electronic Engineering, Chang Gung University, Taoyuan 33302, Taiwan
- Department of Nephrology, Chang Gung Memorial Hospital, Linkou 33302, Taiwan
- Department of Materials Engineering, Ming-Chi University of Technology, New Taipei City 24301, Taiwan
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5
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Kim UJ, Nam SH, Seo J, Yang M, Fu Q, Liu Z, Son H, Lee M, Hahm MG. Visualizing Line Defects in non-van der Waals Bi 2O 2Se Using Raman Spectroscopy. ACS NANO 2022; 16:3637-3646. [PMID: 35166540 DOI: 10.1021/acsnano.1c06598] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
Atomic-layered materials, such as high-quality bismuth oxychalcogenides, which are composed of oppositely charged alternate layers grown using chemical vapor deposition, have attracted considerable attention. Their physical properties are well-suited for high-speed, low-power-consumption optoelectronic devices, and the rapid determination of their crystallographic characteristics is crucial for scalability and integration. In this study, we introduce how the crystallographic structure and quality of such materials can be projected through Raman spectroscopy analysis. Frequency modes at ∼55, ∼78, ∼360, and ∼434 cm-1 were detected, bearing out theoretical calculations from the literature. The low-frequency modes positioned at 55 and 78 cm-1 were activated by structural defects, such as grain boundaries and O-rich edges in the Bi2O2Se crystals, accompanied by sensitivity to the excitation energy. Furthermore, the line defects at ∼55 cm-1 exhibited a strong 2-fold polarization dependence, similar to graphene/graphite edges. Our results can help illuminate the mechanism for activating the Raman-active mode from the infrared active mode by defects, as well as the electronic structures of these two-dimensional layered materials. We also suggest that the nanoscale width line defects in Bi2O2Se can be visualized using Raman spectroscopy.
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Affiliation(s)
- Un Jeong Kim
- Advanced Sensor Laboratory, Samsung Advanced Institute of Technology, Suwon, Gyeonggi-do 16419, Republic of Korea
| | - Seung Hyun Nam
- Department of Materials Science and Engineering, Inha University, 100 Inha-ro, Michuhol-gu, Incheon, 22212, Republic of Korea
| | - Juyeon Seo
- Department of Materials Science and Engineering, Inha University, 100 Inha-ro, Michuhol-gu, Incheon, 22212, Republic of Korea
| | - Mino Yang
- Korea Basic Science Institute Seoul, Seoul, 02841, Republic of Korea
| | - Qundong Fu
- School of Materials Science & Engineering, Nanyang Technological University, 50 Nanyang Avenue, 639798, Singapore
| | - Zheng Liu
- School of Materials Science & Engineering, Nanyang Technological University, 50 Nanyang Avenue, 639798, Singapore
| | - Hyungbin Son
- School of Integrative Engineering, Chung-Ang University, Seoul, 06974, Republic of Korea
| | - Moonsang Lee
- Department of Materials Science and Engineering, Inha University, 100 Inha-ro, Michuhol-gu, Incheon, 22212, Republic of Korea
| | - Myung Gwan Hahm
- Department of Materials Science and Engineering, Inha University, 100 Inha-ro, Michuhol-gu, Incheon, 22212, Republic of Korea
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6
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Sharma T, Sharma R, Kanhere DG. A DFT study of Se n Te n clusters. NANOSCALE ADVANCES 2022; 4:1464-1482. [PMID: 36133684 PMCID: PMC9418643 DOI: 10.1039/d1na00321f] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/03/2021] [Accepted: 01/14/2022] [Indexed: 06/16/2023]
Abstract
First principles calculations have been performed to study the characteristic properties of Se n Te n (n = 5-10) clusters. The present study reveals that the properties of these small clusters are consistent with the properties of Se-Te glassy systems. Several hundred equilibrium structures obtained from a genetic algorithm based USPEX code are relaxed to their minimum energy using the VASP code. Most of the lowest energy buckled ring-like structures are formed from Se-Te heteropolar bonds. Detailed structural analysis and distance energy plots unveil that many equilibrium structures are close in energy to their global minimum. The computed Raman and IR spectra show the dominance of Se-Te heteropolar bonds, consistent with earlier simulation and experimental findings in Se1-x Te x glass materials. Low frequency vibrational modes observed in small clusters are characteristic features of amorphous materials. Non-bonding orbitals (lone pair) are observed in the HOMO, whereas the LUMO is formed from purely antibonding orbitals. The dielectric functions corroborate the bonding mechanism and slightly polar nature of Se n Te n clusters. The energy loss and absorption coefficient indicate the presence of π-plasmons in the UV-visible region. Furthermore, it is ascertained that the use of a hybrid functional (B3LYP) does not affect the properties of small clusters appreciably, except causing a blue shift in the optical spectra. Hence, we find that the small clusters have bearing on the formation of glassy Se-Te systems.
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Affiliation(s)
- Tamanna Sharma
- Department of Physics, Himachal Pradesh University Shimla 171 005 India
| | - Raman Sharma
- Department of Physics, Himachal Pradesh University Shimla 171 005 India
| | - D G Kanhere
- Centre for Modeling and Simulation, Savitribai Phule Pune University Pune 411 007 India
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7
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Liu S, He D, Tan C, Fu S, Han X, Huang M, Miao Q, Zhang X, Wang Y, Peng H, Zhao H. Charge Transfer Properties of Heterostructures Formed by Bi 2 O 2 Se and Transition Metal Dichalcogenide Monolayers. SMALL (WEINHEIM AN DER BERGSTRASSE, GERMANY) 2022; 18:e2106078. [PMID: 34862734 DOI: 10.1002/smll.202106078] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/22/2021] [Indexed: 06/13/2023]
Abstract
Atomically thin bismuth oxyselenide (Bi2 O2 Se) exhibits attractive properties for electronic and optoelectronic applications, such as high charge-carrier mobility and good air stability. Recently, the development of Bi2 O2 Se-based heterostructures have attracted enormous interests with promising prospects for diverse device applications. Although the electrical properties of Bi2 O2 Se-based heterostructures have been widely studied, the interlayer charge transfer in these heterostructures remains elusive, despite its importance in harnessing their emergent functionalities. Here, a comprehensive experimental investigation on the interlayer charge transfer properties of two heterostructures formed by Bi2 O2 Se and representative transition metal dichalcogenides (namely, WS2 /Bi2 O2 Se and MoS2 /Bi2 O2 Se) is reported. Kelvin probe force microscopy is used to measure the work functions of the samples, which are further employed to establish type-II band alignment of both heterostructures. Photoluminescence quenching is observed in each heterostructure, suggesting high charge transfer efficiency. Time-resolved and layer-selective pump-probe measurements further prove the ultrafast interlayer charge transfer processes and formation of long-lived interlayer excitons. These results establish the feasibility of integrating 2D Bi2 O2 Se with other 2D semiconductors to fabricate heterostructures with novel charge transfer properties and provide insight for understanding the performance of optoelectronic devices based on such 2D heterostructures.
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Affiliation(s)
- Shuangyan Liu
- Key Laboratory of Luminescence and Optical Information, Ministry of Education, Institute of Optoelectronic Technology, Beijing Jiaotong University, Beijing, 100044, P. R. China
| | - Dawei He
- Key Laboratory of Luminescence and Optical Information, Ministry of Education, Institute of Optoelectronic Technology, Beijing Jiaotong University, Beijing, 100044, P. R. China
| | - Congwei Tan
- Center for Nanochemistry, Beijing Science and Engineering Center for Nanocarbons, Beijing National Laboratory for Molecular Sciences (BNLMS), College of Chemistry and Molecular Engineering, Peking University, Beijing, 100871, P. R. China
| | - Shaohua Fu
- Key Laboratory of Luminescence and Optical Information, Ministry of Education, Institute of Optoelectronic Technology, Beijing Jiaotong University, Beijing, 100044, P. R. China
| | - Xiuxiu Han
- Key Laboratory of Luminescence and Optical Information, Ministry of Education, Institute of Optoelectronic Technology, Beijing Jiaotong University, Beijing, 100044, P. R. China
| | - Mohan Huang
- Key Laboratory of Luminescence and Optical Information, Ministry of Education, Institute of Optoelectronic Technology, Beijing Jiaotong University, Beijing, 100044, P. R. China
| | - Qing Miao
- Key Laboratory of Luminescence and Optical Information, Ministry of Education, Institute of Optoelectronic Technology, Beijing Jiaotong University, Beijing, 100044, P. R. China
| | - Xiaoxian Zhang
- Key Laboratory of Luminescence and Optical Information, Ministry of Education, Institute of Optoelectronic Technology, Beijing Jiaotong University, Beijing, 100044, P. R. China
| | - Yongsheng Wang
- Key Laboratory of Luminescence and Optical Information, Ministry of Education, Institute of Optoelectronic Technology, Beijing Jiaotong University, Beijing, 100044, P. R. China
| | - Hailin Peng
- Center for Nanochemistry, Beijing Science and Engineering Center for Nanocarbons, Beijing National Laboratory for Molecular Sciences (BNLMS), College of Chemistry and Molecular Engineering, Peking University, Beijing, 100871, P. R. China
| | - Hui Zhao
- Department of Physics and Astronomy, The University of Kansas, Lawrence, KS, 66045, USA
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8
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Wang X, Zhao X, Wang X, Li H, He X, Zhang L. Discovery of New Phases of Bismuth Oxyselenide Semiconductor Bi
2
OSe
2
by Global Structure Search Approach. ADVANCED THEORY AND SIMULATIONS 2021. [DOI: 10.1002/adts.202000316] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Affiliation(s)
- Xueting Wang
- State Key Laboratory of Superhard Materials and College of Physics Jilin University Changchun 130012 China
| | - Xingang Zhao
- Key Laboratory of Automobile Materials of MOE and College of Materials Science and Engineering Jilin University Changchun 130012 China
| | - Xinjiang Wang
- State Key Laboratory of Superhard Materials and College of Physics Jilin University Changchun 130012 China
| | - Hongdong Li
- State Key Laboratory of Superhard Materials and College of Physics Jilin University Changchun 130012 China
| | - Xin He
- Key Laboratory of Automobile Materials of MOE and College of Materials Science and Engineering Jilin University Changchun 130012 China
| | - Lijun Zhang
- Key Laboratory of Automobile Materials of MOE and College of Materials Science and Engineering Jilin University Changchun 130012 China
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9
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Bu K, Luo H, Guo S, Li M, Wang D, Dong H, Ding Y, Yang W, Lü X. Pressure-Regulated Dynamic Stereochemical Role of Lone-Pair Electrons in Layered Bi 2O 2S. J Phys Chem Lett 2020; 11:9702-9707. [PMID: 33136390 DOI: 10.1021/acs.jpclett.0c02893] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Lone-pair electrons (LPEs) ns2 in subvalent 14 and 15 groups lead to highly anharmonic lattice and strong distortion polarization, which are responsible for the groups' outstanding thermoelectric and optoelectronic properties. However, their dynamic stereochemical role in structural and physical properties is still unclear. Here, by introducing pressure to tune the behavior of LPEs, we systematically investigate the lone-pair stereochemical role in a Bi2O2S. The gradually suppressed LPEs during compression show a nonlinear repulsive electrostatic force, resulting in two anisotropic structural transitions. An orthorhombic-to-tetragonal phase transition happens at 6.4 GPa, caused by the dynamic cation centering. This structural transformation effectively modulates the optoelectronic properties. Further compression beyond 13.2 GPa induces a 2D-to-3D structural transition due to the disappearance of the Bi-6s2 LPEs. Therefore, the pressure-induced LPE reconfiguration dominates these anomalous variations of lattice, electronic, and optical properties. Our findings provide new insights into the materials optimization by regulating the characters of LPEs.
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Affiliation(s)
- Kejun Bu
- Center for High Pressure Science and Technology Advanced Research (HPSTAR), 1690 Cailun Road, Shanghai 201203, P. R. China
| | - Hui Luo
- Center for High Pressure Science and Technology Advanced Research (HPSTAR), 1690 Cailun Road, Shanghai 201203, P. R. China
| | - Songhao Guo
- Center for High Pressure Science and Technology Advanced Research (HPSTAR), 1690 Cailun Road, Shanghai 201203, P. R. China
| | - Mei Li
- Center for High Pressure Science and Technology Advanced Research (HPSTAR), 1690 Cailun Road, Shanghai 201203, P. R. China
| | - Dong Wang
- Center for High Pressure Science and Technology Advanced Research (HPSTAR), 1690 Cailun Road, Shanghai 201203, P. R. China
| | - Hongliang Dong
- Center for High Pressure Science and Technology Advanced Research (HPSTAR), 1690 Cailun Road, Shanghai 201203, P. R. China
| | - Yang Ding
- Center for High Pressure Science and Technology Advanced Research (HPSTAR), 1690 Cailun Road, Shanghai 201203, P. R. China
| | - Wenge Yang
- Center for High Pressure Science and Technology Advanced Research (HPSTAR), 1690 Cailun Road, Shanghai 201203, P. R. China
| | - Xujie Lü
- Center for High Pressure Science and Technology Advanced Research (HPSTAR), 1690 Cailun Road, Shanghai 201203, P. R. China
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10
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Xu L, Luo YC, Lv YY, Zhang YY, Wu YZ, Yao SH, Zhou J, Chen YB, Chen YF. Electrical scattering mechanism evolution in un-doped and halogen-doped Bi 2O 2Se single crystals. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2020; 32:365705. [PMID: 32380483 DOI: 10.1088/1361-648x/ab913f] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/19/2020] [Accepted: 05/07/2020] [Indexed: 06/11/2023]
Abstract
Recently the layered oxide semiconductor Bi2O2Se was hotly explored for its ultrahigh mobility and ultrafast photo-response whose physical origins need to be further explored or elucidated. Here, we have grown halogen (Cl, Br, I) doped and un-doped Bi2O2Se single crystals by a melt-solidification method. Comparative electrical transport characterizations and detailed data-analysis substantiate that the electron-electron scattering is the major source of resistivity in un-doped Bi2O2Se crystals; however, in halogen-doped Bi2O2Se crystals, electron-electron scattering is only effective at low temperature (<60 K) and subsequently electron-phonon-interaction scattering is dominated to resistivity. Hall measurement and analysis show that electron concentration of halogen-doped Bi2O2Se (∼1020cm-3) is one-order higher than un-doped one (∼1019cm-3), but the carrier mobility of halogen-doped Bi2O2Se at 2 K (∼102cm2V-1s-1) is reduced by more than two orders than un-doped ones (∼104cm2V-1s-1). Three kinds of relaxation time (due to the impurity scattering, electron-electron scattering and electron-phonon scattering), calculated by linear-response theory and electron-/phonon-dispersion, are in agreement with experimental results quantitatively. The scattering mechanism evolution from sole electron-electron scattering (un-doped Bi2O2Se) to electron-phonon scattering (doped Bi2O2Se) at high temperature (>60 K) is attributed to the net effect of decreased screened Coulomb-interaction and increased Fermi energy in halogen-doped Bi2O2Se. This work may provide clues of physical origins of superior electrical/photoelectrical properties of Bi2O2Se.
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Affiliation(s)
- Lu Xu
- National Laboratory of Solid State Microstructures, Nanjing University, Nanjing 210093, People's Republic of China
- Department of Materials Science and Engineering, Nanjing University, Nanjing 210093, People's Republic of China
| | - Ye-Cheng Luo
- National Laboratory of Solid State Microstructures, Nanjing University, Nanjing 210093, People's Republic of China
- Department of Physics, Nanjing University, Nanjing 210093, People's Republic of China
| | - Yang-Yang Lv
- National Laboratory of Solid State Microstructures, Nanjing University, Nanjing 210093, People's Republic of China
- Department of Physics, Nanjing University, Nanjing 210093, People's Republic of China
| | - Yan-Yan Zhang
- National Laboratory of Solid State Microstructures, Nanjing University, Nanjing 210093, People's Republic of China
- Department of Materials Science and Engineering, Nanjing University, Nanjing 210093, People's Republic of China
| | - Yi-Zhang Wu
- National Laboratory of Solid State Microstructures, Nanjing University, Nanjing 210093, People's Republic of China
- Department of Physics, Nanjing University, Nanjing 210093, People's Republic of China
| | - Shu-Hua Yao
- National Laboratory of Solid State Microstructures, Nanjing University, Nanjing 210093, People's Republic of China
- Department of Materials Science and Engineering, Nanjing University, Nanjing 210093, People's Republic of China
| | - Jian Zhou
- National Laboratory of Solid State Microstructures, Nanjing University, Nanjing 210093, People's Republic of China
- Department of Materials Science and Engineering, Nanjing University, Nanjing 210093, People's Republic of China
| | - Y B Chen
- National Laboratory of Solid State Microstructures, Nanjing University, Nanjing 210093, People's Republic of China
- Department of Physics, Nanjing University, Nanjing 210093, People's Republic of China
- Collaborative Innovation Center of Advanced Microstructure, Nanjing University, Nanjing 210093, People's Republic of China
| | - Yan-Feng Chen
- National Laboratory of Solid State Microstructures, Nanjing University, Nanjing 210093, People's Republic of China
- Department of Materials Science and Engineering, Nanjing University, Nanjing 210093, People's Republic of China
- Collaborative Innovation Center of Advanced Microstructure, Nanjing University, Nanjing 210093, People's Republic of China
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Ghosh T, Samanta M, Vasdev A, Dolui K, Ghatak J, Das T, Sheet G, Biswas K. Ultrathin Free-Standing Nanosheets of Bi 2O 2Se: Room Temperature Ferroelectricity in Self-Assembled Charged Layered Heterostructure. NANO LETTERS 2019; 19:5703-5709. [PMID: 31347854 DOI: 10.1021/acs.nanolett.9b02312] [Citation(s) in RCA: 59] [Impact Index Per Article: 11.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/17/2023]
Abstract
Ultrathin ferroelectric semiconductors with high charge carrier mobility are much coveted systems for the advancement of various electronic and optoelectronic devices. However, in traditional oxide ferroelectric insulators, the ferroelectric transition temperature decreases drastically with decreasing material thickness and ceases to exist below certain critical thickness owing to depolarizing fields. Herein, we show the emergence of an ordered ferroelectric ground state in ultrathin (∼2 nm) single crystalline nanosheets of Bi2O2Se at room temperature. Free-standing ferroelectric nanosheets, in which oppositely charged alternating layers are self-assembled together by electrostatic interactions, are synthesized by a simple, rapid, and scalable wet chemical procedure at room temperature. The existence of ferroelectricity in Bi2O2Se nanosheets is confirmed by dielectric measurements and piezoresponse force spectroscopy. The spontaneous orthorhombic distortion in the ultrathin nanosheets breaks the local inversion symmetry, thereby resulting in ferroelectricity. The local structural distortion and the formation of spontaneous dipole moment were directly probed by atomic resolution scanning transmission electron microscopy and density functional theory calculations.
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Affiliation(s)
- Tanmoy Ghosh
- New Chemistry Unit , Jawaharlal Nehru Centre for Advanced Scientific Research (JNCASR) , Jakkur, Bangalore 560064 , India
| | - Manisha Samanta
- New Chemistry Unit , Jawaharlal Nehru Centre for Advanced Scientific Research (JNCASR) , Jakkur, Bangalore 560064 , India
| | - Aastha Vasdev
- Department of Physical Sciences , Indian Institute of Science Education and Research Mohali , Sector 81, S. A. S. Nagar, Manauli 140306 , India
| | - Kapildeb Dolui
- Department of Physics and Astronomy , University of Delaware , Newark , Delaware 19716-2570 , United States
| | - Jay Ghatak
- International Centre for Materials Science , Jawaharlal Nehru Centre for Advanced Scientific Research (JNCASR) , Jakkur, Bangalore 560064 , India
| | - Tanmoy Das
- Department of Physics , Indian Institute of Science , Bangalore 560012 , India
| | - Goutam Sheet
- Department of Physical Sciences , Indian Institute of Science Education and Research Mohali , Sector 81, S. A. S. Nagar, Manauli 140306 , India
| | - Kanishka Biswas
- New Chemistry Unit , Jawaharlal Nehru Centre for Advanced Scientific Research (JNCASR) , Jakkur, Bangalore 560064 , India
- International Centre for Materials Science , Jawaharlal Nehru Centre for Advanced Scientific Research (JNCASR) , Jakkur, Bangalore 560064 , India
- School of Advanced Materials , Jawaharlal Nehru Centre for Advanced Scientific Research (JNCASR) , Jakkur, Bangalore 560064 , India
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