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Kjeldby SB, Nguyen PD, García-Fernández J, Haug K, Galeckas A, Jensen IJT, Thøgersen A, Vines L, Prytz Ø. Optical properties of ZnFe 2O 4 nanoparticles and Fe-decorated inversion domain boundaries in ZnO. NANOSCALE ADVANCES 2023; 5:2102-2110. [PMID: 36998644 PMCID: PMC10044669 DOI: 10.1039/d2na00849a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/25/2022] [Accepted: 02/24/2023] [Indexed: 06/19/2023]
Abstract
The maximum efficiency of solar cells utilizing a single layer for photovoltaic conversion is given by the single junction Shockley-Queisser limit. In tandem solar cells, a stack of materials with different band gaps contribute to the conversion, enabling tandem cells to exceed the single junction Shockley-Queisser limit. An intriguing variant of this approach is to embed semiconducting nanoparticles in a transparent conducting oxide (TCO) solar cell front contact. This alternative route would enhance the functionality of the TCO layer, allowing it to participate directly in photovoltaic conversion via photon absorption and charge carrier generation in the nanoparticles. Here, we demonstrate the functionalization of ZnO through incorporation of either ZnFe2O4 spinel nanoparticles (NPs) or inversion domain boundaries (IDBs) decorated by Fe. Diffuse reflectance spectroscopy and electron energy loss spectroscopy show that samples containing spinel particles and samples containing IDBs decorated by Fe both display enhanced absorption in the visible range at around 2.0 and 2.6 eV. This striking functional similarity was attributed to the local structural similarity around Fe-ions in spinel ZnFe2O4 and at Fe-decorated basal IDBs. Hence, functional properties of the ZnFe2O4 arise already for the two-dimensional basal IDBs, from which these planar defects behave like two-dimensional spinel-like inclusions in ZnO. Cathodoluminescence spectra reveal an increased luminescence around the band edge of spinel ZnFe2O4 when measuring on the spinel ZnFe2O4 NPs embedded in ZnO, whereas spectra from Fe-decorated IDBs could be deconvoluted into luminescence contributions from bulk ZnO and bulk ZnFe2O4.
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Affiliation(s)
- S B Kjeldby
- Centre for Materials Science and Nanotechnology, University of Oslo N-0318 Oslo Norway
| | - P D Nguyen
- Centre for Materials Science and Nanotechnology, University of Oslo N-0318 Oslo Norway
| | - J García-Fernández
- Centre for Materials Science and Nanotechnology, University of Oslo N-0318 Oslo Norway
| | - K Haug
- Centre for Materials Science and Nanotechnology, University of Oslo N-0318 Oslo Norway
| | - A Galeckas
- Centre for Materials Science and Nanotechnology, University of Oslo N-0318 Oslo Norway
| | - I J T Jensen
- Centre for Materials Science and Nanotechnology, University of Oslo N-0318 Oslo Norway
- SINTEF Industry, Sustainable Energy Technology N-0314 Oslo Norway
| | - A Thøgersen
- SINTEF Industry, Sustainable Energy Technology N-0314 Oslo Norway
| | - L Vines
- Centre for Materials Science and Nanotechnology, University of Oslo N-0318 Oslo Norway
| | - Ø Prytz
- Centre for Materials Science and Nanotechnology, University of Oslo N-0318 Oslo Norway
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Liu X, Garcia-Mendez R, Lupini AR, Cheng Y, Hood ZD, Han F, Sharafi A, Idrobo JC, Dudney NJ, Wang C, Ma C, Sakamoto J, Chi M. Local electronic structure variation resulting in Li 'filament' formation within solid electrolytes. NATURE MATERIALS 2021; 20:1485-1490. [PMID: 34059815 DOI: 10.1038/s41563-021-01019-x] [Citation(s) in RCA: 79] [Impact Index Per Article: 26.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/25/2018] [Accepted: 04/22/2021] [Indexed: 05/15/2023]
Abstract
Solid electrolytes hold great promise for enabling the use of Li metal anodes. The main problem is that during cycling, Li can infiltrate along grain boundaries and cause short circuits, resulting in potentially catastrophic battery failure. At present, this phenomenon is not well understood. Here, through electron microscopy measurements on a representative system, Li7La3Zr2O12, we discover that Li infiltration in solid oxide electrolytes is strongly associated with local electronic band structure. About half of the Li7La3Zr2O12 grain boundaries were found to have a reduced bandgap, around 1-3 eV, making them potential channels for leakage current. Instead of combining with electrons at the cathode, Li+ ions are hence prematurely reduced by electrons at grain boundaries, forming local Li filaments. The eventual interconnection of these filaments results in a short circuit. Our discovery reveals that the grain-boundary electronic conductivity must be a primary concern for optimization in future solid-state battery design.
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Affiliation(s)
- Xiaoming Liu
- Center for Nanophase Materials Sciences, Oak Ridge National Laboratory, Oak Ridge, TN, USA
| | - Regina Garcia-Mendez
- Department of Materials Science and Engineering, University of Michigan, Ann Arbor, MI, USA
| | - Andrew R Lupini
- Center for Nanophase Materials Sciences, Oak Ridge National Laboratory, Oak Ridge, TN, USA
| | - Yongqiang Cheng
- Neutron Scattering Division, Oak Ridge National Laboratory, Oak Ridge, TN, USA
| | - Zachary D Hood
- School of Chemistry and Biochemistry, Georgia Institute of Technology, Atlanta, GA, USA
| | - Fudong Han
- Department of Chemical and Bimolecular Engineering, University of Maryland, College Park, MD, USA
| | - Asma Sharafi
- Department of Materials Science and Engineering, University of Michigan, Ann Arbor, MI, USA
| | - Juan Carlos Idrobo
- Center for Nanophase Materials Sciences, Oak Ridge National Laboratory, Oak Ridge, TN, USA
| | - Nancy J Dudney
- Chemical Sciences Division, Oak Ridge National Laboratory, Oak Ridge, TN, USA
| | - Chunsheng Wang
- Department of Chemical and Bimolecular Engineering, University of Maryland, College Park, MD, USA
| | - Cheng Ma
- Hefei National Laboratory for Physical Sciences at the Microscale, Department of Materials Science and Engineering, CAS Key Laboratory of Materials for Energy Conversion, University of Science and Technology of China, Hefei, China.
| | - Jeff Sakamoto
- Department of Materials Science and Engineering, University of Michigan, Ann Arbor, MI, USA.
| | - Miaofang Chi
- Center for Nanophase Materials Sciences, Oak Ridge National Laboratory, Oak Ridge, TN, USA.
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Zhan W, Kosinskiy AY, Vines L, Johansen KM, Carvalho PA, Prytz Ø. ZnCr₂O₄ Inclusions in ZnO Matrix Investigated by Probe-Corrected STEM-EELS. MATERIALS (BASEL, SWITZERLAND) 2019; 12:ma12060888. [PMID: 30884841 PMCID: PMC6471317 DOI: 10.3390/ma12060888] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 03/04/2019] [Revised: 03/12/2019] [Accepted: 03/13/2019] [Indexed: 06/09/2023]
Abstract
The ZnCr₂O₄/ZnO materials system has a wide range of potential applications, for example, as a photocatalytic material for waste-water treatment and gas sensing. In this study, probe-corrected high-resolution scanning transmission electron microscopy and geometric phase analysis were utilized to study the dislocation structure and strain distribution at the interface between zinc oxide (ZnO) and embedded zinc chromium oxide (ZnCr₂O₄) particles. Ball-milled and dry-pressed ZnO and chromium oxide (α-Cr₂O₃) powder formed ZnCr₂O₄ inclusions in ZnO with size ~400 nm, where the interface properties depended on the interface orientation. In particular, sharp interfaces were observed for ZnO [2113]/ZnCr₂O₄ [110] orientations, while ZnO [1210]/ZnCr₂O₄ [112] orientations revealed an interface over several atomic layers, with a high density of dislocations. Further, monochromated electron energy-loss spectroscopy was employed to map the optical band gap of ZnCr₂O₄ nanoparticles in the ZnO matrix and their interface, where the average band gap of ZnCr₂O4 nanoparticles was measured to be 3.84 ± 0.03 eV, in contrast to 3.22 ± 0.01 eV for the ZnO matrix.
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Affiliation(s)
- Wei Zhan
- Department of Physics, Centre for Materials Science and Nanotechnology, University of Oslo, N-0316 Oslo, Norway.
| | - Andrey Yurievich Kosinskiy
- Department of Physics, Centre for Materials Science and Nanotechnology, University of Oslo, N-0316 Oslo, Norway.
| | - Lasse Vines
- Department of Physics, Centre for Materials Science and Nanotechnology, University of Oslo, N-0316 Oslo, Norway.
| | - Klaus Magnus Johansen
- Department of Physics, Centre for Materials Science and Nanotechnology, University of Oslo, N-0316 Oslo, Norway.
| | | | - Øystein Prytz
- Department of Physics, Centre for Materials Science and Nanotechnology, University of Oslo, N-0316 Oslo, Norway.
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Zhan W, Venkatachalapathy V, Aarholt T, Kuznetsov AY, Prytz Ø. Band gap maps beyond the delocalization limit: correlation between optical band gaps and plasmon energies at the nanoscale. Sci Rep 2018; 8:848. [PMID: 29339788 PMCID: PMC5770386 DOI: 10.1038/s41598-017-18949-9] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2017] [Accepted: 12/20/2017] [Indexed: 11/16/2022] Open
Abstract
Recent progresses in nanoscale semiconductor technology have heightened the need for measurements of band gaps with high spatial resolution. Band gap mapping can be performed through a combination of probe-corrected scanning transmission electron microscopy (STEM) and monochromated electron energy-loss spectroscopy (EELS), but are rare owing to the complexity of the experiments and the data analysis. Furthermore, although this method is far superior in terms of spatial resolution to any other techniques, it is still fundamentally resolution-limited due to inelastic delocalization of the EELS signal. In this work we have established a quantitative correlation between optical band gaps and plasmon energies using the Zn1−xCdxO/ZnO system as an example, thereby side-stepping the fundamental resolution limits of band gap measurements, and providing a simple and convenient approach to achieve band gap maps with unprecedented spatial resolution.
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Affiliation(s)
- Wei Zhan
- Department of Physics, Centre for Materials Science and Nanotechnology, University of Oslo, P.O. Box 1048 Blindern, N-0316, Oslo, Norway
| | - Vishnukanthan Venkatachalapathy
- Department of Physics, Centre for Materials Science and Nanotechnology, University of Oslo, P.O. Box 1048 Blindern, N-0316, Oslo, Norway
| | - Thomas Aarholt
- Department of Physics, Centre for Materials Science and Nanotechnology, University of Oslo, P.O. Box 1048 Blindern, N-0316, Oslo, Norway
| | - Andrej Yu Kuznetsov
- Department of Physics, Centre for Materials Science and Nanotechnology, University of Oslo, P.O. Box 1048 Blindern, N-0316, Oslo, Norway
| | - Øystein Prytz
- Department of Physics, Centre for Materials Science and Nanotechnology, University of Oslo, P.O. Box 1048 Blindern, N-0316, Oslo, Norway.
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Granerød CS, Zhan W, Prytz Ø. Automated approaches for band gap mapping in STEM-EELS. Ultramicroscopy 2018; 184:39-45. [DOI: 10.1016/j.ultramic.2017.08.006] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2017] [Revised: 07/06/2017] [Accepted: 08/15/2017] [Indexed: 11/24/2022]
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