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Dzhagan V, Mazur N, Kapush O, Selyshchev O, Karnaukhov A, Yeshchenko OA, Danylenko MI, Yukhymchuk V, Zahn DRT. Core and Shell Contributions to the Phonon Spectra of CdTe/CdS Quantum Dots. NANOMATERIALS (BASEL, SWITZERLAND) 2023; 13:921. [PMID: 36903799 PMCID: PMC10004847 DOI: 10.3390/nano13050921] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 02/13/2023] [Revised: 02/20/2023] [Accepted: 03/01/2023] [Indexed: 06/18/2023]
Abstract
The parameters of the shell and interface in semiconductor core/shell nanocrystals (NCs) are determinant for their optical properties and charge transfer but are challenging to be studied. Raman spectroscopy was shown earlier to be a suitable informative probe of the core/shell structure. Here, we report the results of a spectroscopic study of CdTe NCs synthesized by a facile route in water, using thioglycolic acid (TGA) as a stabilizer. Both core-level X-ray photoelectron (XPS) and vibrational (Raman and infrared) spectra show that using thiol during the synthesis results in the formation of a CdS shell around the CdTe core NCs. Even though the spectral positions of the optical absorption and photoluminescence bands of such NCs are determined by the CdTe core, the far-infrared absorption and resonant Raman scattering spectra are dominated by the vibrations related with the shell. The physical mechanism of the observed effect is discussed and opposed to the results reported before for thiol-free CdTe Ns as well as CdSe/CdS and CdSe/ZnS core/shell NC systems, where the core phonons were clearly detected under similar experimental conditions.
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Affiliation(s)
- Volodymyr Dzhagan
- V. Lashkaryov Institute of Semiconductors Physics, National Academy of Sciences of Ukraine, 03028 Kyiv, Ukraine
- Physics Department, Taras Shevchenko National University of Kyiv, 01601 Kyiv, Ukraine
| | - Nazar Mazur
- V. Lashkaryov Institute of Semiconductors Physics, National Academy of Sciences of Ukraine, 03028 Kyiv, Ukraine
| | - Olga Kapush
- V. Lashkaryov Institute of Semiconductors Physics, National Academy of Sciences of Ukraine, 03028 Kyiv, Ukraine
| | - Oleksandr Selyshchev
- Semiconductor Physics, Chemnitz University of Technology, D-09107 Chemnitz, Germany
- Center for Materials, Architectures, and Integration of Nanomembranes (MAIN), Chemnitz University of Technology, D-09107 Chemnitz, Germany
| | - Anatolii Karnaukhov
- V. Lashkaryov Institute of Semiconductors Physics, National Academy of Sciences of Ukraine, 03028 Kyiv, Ukraine
| | - Oleg A. Yeshchenko
- Physics Department, Taras Shevchenko National University of Kyiv, 01601 Kyiv, Ukraine
| | - Mykola I. Danylenko
- Frantsevich Institute for Problems of Materials Science, National Academy of Sciences of Ukraine, 03142 Kyiv, Ukraine
| | - Volodymyr Yukhymchuk
- V. Lashkaryov Institute of Semiconductors Physics, National Academy of Sciences of Ukraine, 03028 Kyiv, Ukraine
| | - Dietrich R. T. Zahn
- Semiconductor Physics, Chemnitz University of Technology, D-09107 Chemnitz, Germany
- Center for Materials, Architectures, and Integration of Nanomembranes (MAIN), Chemnitz University of Technology, D-09107 Chemnitz, Germany
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Havryliuk Y, Dzhagan V, Karnaukhov A, Selyshchev O, Hann J, Zahn DRT. Raman Spectroscopy and Thermoelectric Characterization of Composite Thin Films of Cu 2ZnSnS 4 Nanocrystals Embedded in a Conductive Polymer PEDOT:PSS. NANOMATERIALS (BASEL, SWITZERLAND) 2022; 13:nano13010041. [PMID: 36615951 PMCID: PMC9824269 DOI: 10.3390/nano13010041] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/01/2022] [Revised: 12/16/2022] [Accepted: 12/20/2022] [Indexed: 06/12/2023]
Abstract
Cu2ZnSnS4 (CZTS) is an intensively studied potential solar cell absorber and a promising thermoelectric (TE) material. In the form of colloidal nanocrystals (NCs), it is very convenient to form thin films on various substrates. Here, we investigate composites of CZTS NCs with PEDOT:PSS, a widely used photovoltaics polymer. We focus on the investigation of the structural stability of both NCs and polymers in composite thin films with different NC-to-polymer ratios. We studied both pristine films and those subjected to flash lamp annealing (FLA) or laser irradiation with various power densities. Raman spectroscopy was used as the main characterization technique because the vibrational modes of CZTS NCs and the polymer can be acquired in one spectrum and thus allow the properties of both parts of the composite to be monitored simultaneously. We found that CZTS NCs and PEDOT:PSS mutually influence each other in the composite. The thermoelectric properties of PEDOT:PSS/CZTS composite films were found to be higher compared to the films consisting of bare materials, and they can be further improved by adding DMSO. However, the presence of NCs in the polymer deteriorates its structural stability when subjected to FLA or laser treatment.
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Affiliation(s)
- Yevhenii Havryliuk
- Semiconductor Physics, Chemnitz University of Technology, 09107 Chemnitz, Germany
- Center for Materials, Architectures, and Integration of Nanomembranes (MAIN), 09126 Chemnitz, Germany
- V.E. Lashkaryov Institute of Semiconductor Physics NAS of Ukraine, 03028 Kyiv, Ukraine
| | - Volodymyr Dzhagan
- V.E. Lashkaryov Institute of Semiconductor Physics NAS of Ukraine, 03028 Kyiv, Ukraine
- Physics Department, Taras Shevchenko National University of Kyiv, 60 Volodymyrs'ka str., 01601 Kyiv, Ukraine
| | - Anatolii Karnaukhov
- V.E. Lashkaryov Institute of Semiconductor Physics NAS of Ukraine, 03028 Kyiv, Ukraine
| | - Oleksandr Selyshchev
- Semiconductor Physics, Chemnitz University of Technology, 09107 Chemnitz, Germany
- Center for Materials, Architectures, and Integration of Nanomembranes (MAIN), 09126 Chemnitz, Germany
| | - Julia Hann
- Center for Materials, Architectures, and Integration of Nanomembranes (MAIN), 09126 Chemnitz, Germany
| | - Dietrich R T Zahn
- Semiconductor Physics, Chemnitz University of Technology, 09107 Chemnitz, Germany
- Center for Materials, Architectures, and Integration of Nanomembranes (MAIN), 09126 Chemnitz, Germany
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