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Hou Q, Buckeridge J, Walsh A, Xie Z, Lu Y, Keal TW, Guan J, Woodley SM, Catlow CRA, Sokol AA. The Interplay of Interstitial and Substitutional Copper in Zinc Oxide. Front Chem 2022; 9:780935. [PMID: 34970531 PMCID: PMC8712339 DOI: 10.3389/fchem.2021.780935] [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: 09/22/2021] [Accepted: 11/23/2021] [Indexed: 11/13/2022] Open
Abstract
Cu impurities are reported to have significant effects on the electrical and optical properties of bulk ZnO. In this work, we study the defect properties of Cu in ZnO using hybrid quantum mechanical/molecular mechanical (QM/MM)–embedded cluster calculations based on a multi-region approach that allows us to model defects at the true dilute limit, with polarization effects described in an accurate and consistent manner. We compute the electronic structure, energetics, and geometries of Cu impurities, including substitutional and interstitial configurations, and analyze their effects on the electronic structure. Under ambient conditions, CuZn is the dominant defect in the d9 state and remains electronically passive. We find that, however, as we approach typical vacuum conditions, the interstitial Cu defect becomes significant and can act as an electron trap.
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Affiliation(s)
- Qing Hou
- Institute of Photonic Chips, University of Shanghai for Science and Technology, Shanghai, China.,School of Materials and Chemistry, University of Shanghai for Science and Technology, Shanghai, China.,Department of Chemistry, Kathleen Lonsdale Materials Chemistry, University College London, London, United Kingdom
| | - John Buckeridge
- School of Engineering, London South Bank University, London, United Kingdom
| | - Aron Walsh
- Department of Materials, Imperial College London, London, United Kingdom
| | - Zijuan Xie
- Shenzhen Institute for Quantum Science and Technology and Department of Physics, Southern University of Science and Technology, Shenzhen, China
| | - You Lu
- Scientific Computing Department, UKRI STFC Daresbury Laboratory, Warrington, United Kingdom
| | - Thomas W Keal
- Scientific Computing Department, UKRI STFC Daresbury Laboratory, Warrington, United Kingdom
| | - Jingcheng Guan
- Department of Chemistry, Kathleen Lonsdale Materials Chemistry, University College London, London, United Kingdom
| | - Scott M Woodley
- Department of Chemistry, Kathleen Lonsdale Materials Chemistry, University College London, London, United Kingdom
| | - C Richard A Catlow
- Department of Chemistry, Kathleen Lonsdale Materials Chemistry, University College London, London, United Kingdom.,School of Chemistry, Cardiff University, Cardiff, United Kingdom
| | - Alexey A Sokol
- Department of Chemistry, Kathleen Lonsdale Materials Chemistry, University College London, London, United Kingdom
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Volnianska O. Computational studies of the electronic structure of copper-doped ZnO quantum dots. J Chem Phys 2021; 154:124710. [PMID: 33810646 DOI: 10.1063/5.0039522] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023] Open
Abstract
Copper-doped ZnO quantum dots (QDs) have attracted substantial interest. The electronic structure and optical and magnetic properties of Cu3+(d8)-, Cu2+(d9)-, and Cu+(d10)-doped ZnO QDs with sizes up to 1.5 nm are investigated using the GGA+U approximation, with the +U corrections applied to d (Zn), p(O), and d(Cu) orbitals. Taking +Us parameters, as optimized in previous bulk calculations, we obtain the correct band structure of ZnO QDs. Both the description of electronic structure and thermodynamic charge state transitions of Cu in ZnO QDs agree with the results of bulk calculations due to the strong localization of Cu defect energy levels. Atomic displacements around Cu are induced by strong Jahn-Teller distortion and affect Kohn-Sham energies and thermodynamic transition levels. The average bond length of Cu-O and the defect structure are crucial factors influencing the electronic properties of Cu in ZnO QDs. The analysis of the optical properties of Cu in ZnO QDs is reported. The GGA+U results, compared with the available experimental data, support Dingle's model [Phys. Rev. Lett. 23, 579 (1969)], in which the structured green luminescence observed in bulk and nanocrystals originates from the [(Cu+, hole) → Cu2+] transition. We also examine the magnetic interaction between the copper pair for two charge states: 0 and +2, and four positions relative to the center of QDs. Ferromagnetic interaction between ions is obtained for every investigated configuration. The magnitude of ferromagnetism increases for positive charge defects due to the strong hybridization of the d(Cu) and p(O) states.
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Affiliation(s)
- O Volnianska
- Institute of Physics PAS, al. Lotników 32/46, 02-668 Warsaw, Poland
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Wawrzyńczyk D, Cichy B, Stęk W, Nyk M. The role of l-cysteine and introduced surface defects in reactive oxygen species generation by ZnO nanoparticles. Dalton Trans 2018; 47:8320-8329. [PMID: 29893391 DOI: 10.1039/c8dt00725j] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Abstract
The synthesis and surface functionalization of ZnO nanoparticles were performed, with attention being paid to the possible bio-related applications in light-triggered reactive oxygen species generation.
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Affiliation(s)
- Dominika Wawrzyńczyk
- Advanced Materials Engineering and Modelling Group
- Faculty of Chemistry
- Wrocław University of Science and Technology
- 50-370 Wrocław
- Poland
| | - Bartłomiej Cichy
- Institute of Low Temperature and Structure Research
- 50-422 Wrocław
- Poland
| | - Wiesław Stęk
- Institute of Low Temperature and Structure Research
- 50-422 Wrocław
- Poland
| | - Marcin Nyk
- Advanced Materials Engineering and Modelling Group
- Faculty of Chemistry
- Wrocław University of Science and Technology
- 50-370 Wrocław
- Poland
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Ye H, Su Z, Tang F, Wang M, Chen G, Wang J, Xu S. Excitation Dependent Phosphorous Property and New Model of the Structured Green Luminescence in ZnO. Sci Rep 2017; 7:41460. [PMID: 28150699 PMCID: PMC5288693 DOI: 10.1038/srep41460] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2016] [Accepted: 12/13/2016] [Indexed: 11/24/2022] Open
Abstract
The copper induced green luminescence (GL) with two sets of fine structures in ZnO crystal has been found for several decades (i.e., R. Dingle, Phys. Rev. Lett. 23, 579 (1969)), but the physical origin of the doublet still remains as an open question up to now. In this paper, we provide new insight into the mechanism of the structured GL band in terms of new experimental findings and theoretical calculations. It is found, for the first time, that the GL signal exhibits persistent afterglow for tens of minutes after the switch-off of below-band-gap excitation light but it cannot occur under above-band-gap excitation. Such a phosphorous property may be interpreted as de-trapping and feeding of electrons from a shallow trapping level via the conduction band to the Cu-related luminescence centers where the Cu3+ ion is proposed to work as the final state of the GL emission. From first-principles calculation, such a Cu3+ ion in wurtzite ZnO prefers a high spin 3d8 state with two non-degenerated half-filled orbitals due to the Jahn-Teller effect, probably leading to the double structures in photoluminescence spectrum. Therefore, this model gives a comprehensively new understanding on the mechanism of the structured GL band in ZnO.
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Affiliation(s)
- Honggang Ye
- Department of Physics, Shenzhen Institute of Research and Innovation, The University of Hong Kong, Pokfulam Road, Hong Kong, China.,Department of Applied Physics, Xi'an Jiaotong University, Xi'an 710049, China
| | - Zhicheng Su
- Department of Physics, Shenzhen Institute of Research and Innovation, The University of Hong Kong, Pokfulam Road, Hong Kong, China
| | - Fei Tang
- Department of Physics, Shenzhen Institute of Research and Innovation, The University of Hong Kong, Pokfulam Road, Hong Kong, China
| | - Mingzheng Wang
- Department of Physics, Shenzhen Institute of Research and Innovation, The University of Hong Kong, Pokfulam Road, Hong Kong, China
| | - Guangde Chen
- Department of Applied Physics, Xi'an Jiaotong University, Xi'an 710049, China
| | - Jian Wang
- Department of Physics, Shenzhen Institute of Research and Innovation, The University of Hong Kong, Pokfulam Road, Hong Kong, China
| | - Shijie Xu
- Department of Physics, Shenzhen Institute of Research and Innovation, The University of Hong Kong, Pokfulam Road, Hong Kong, China
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Hu L, Huang J, He H, Zhu L, Liu S, Jin Y, Sun L, Ye Z. Dual-donor (Zn(i) and V(O)) mediated ferromagnetism in copper-doped ZnO micron-scale polycrystalline films: a thermally driven defect modulation process. NANOSCALE 2013; 5:3918-3930. [PMID: 23532361 DOI: 10.1039/c3nr00136a] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
The paper reports robust ferromagnetic Cu-doped ZnO micron-scale polycrystalline films via spin-coating using high-quality doped nanocrystals. A reliable magnetic response is observed in the 900 °C vacuum annealed film without any ferromagnetic contribution from other sources. Post-annealing treatment in terms of atmosphere and temperature can control the proportion of oxygen vacancies (V(O)) and zinc interstitials (Zn(i)) defects and further help to precisely regulate defect-related ferromagnetic behavior. Complex charge transfer processes derived from dual-donor (Zn(i) and V(O)) to Cu acceptor are revealed by photoluminescence (PL) and electron paramagnetic resonance (EPR) spectra. Based on the above, specific charge transfer (CT)-type Stoner splitting and indirect double-exchange mechanisms are proposed to understand the ferromagnetic origin. The improvable FM performance and annealing-specific modulation further indicate that a thermal driven process can delicately tailor the magnetic property of the transition metal ion-doped ZnO system.
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Affiliation(s)
- Liang Hu
- State Key Laboratory of Silicon Materials, Dept. of Materials, Zhejiang University, Hangzhou, 310027, People's Republic of China
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Gallino F, Di Valentin C, Pacchioni G. Band gap engineering of bulk ZrO2 by Ti doping. Phys Chem Chem Phys 2011; 13:17667-75. [DOI: 10.1039/c1cp21987a] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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