Distinction between alloyed Perovskite and elpasolite nanocrystals

In the previous decade, a lot of research has been done in the area of halide perovskite materials which has led them to be used in all different typed of photonic applications. The low dimension crystals of this structure have also shown a lot of promise in quantum photonic devices. We synthesize p...

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Main Authors: Mishra, Pritish, Zhang, Mengyuan, Chen, Andy Paul, Sum, Tze Chien, Duchamp, Martial, Lam, Yeng Ming, Hippalgaonkar, Kedar
Other Authors: Interdisciplinary Graduate School (IGS)
Format: Conference or Workshop Item
Language:English
Published: 2023
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Online Access:https://hdl.handle.net/10356/169883
https://www.imc20.kr/
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spelling sg-ntu-dr.10356-1698832023-08-20T15:35:52Z Distinction between alloyed Perovskite and elpasolite nanocrystals Mishra, Pritish Zhang, Mengyuan Chen, Andy Paul Sum, Tze Chien Duchamp, Martial Lam, Yeng Ming Hippalgaonkar, Kedar Interdisciplinary Graduate School (IGS) School of Materials Science and Engineering School of Physical and Mathematical Sciences 20th International Microscopy Congress (IMC20) Institute of Materials Research and Engineering, A*STAR Energy Research Institute @ NTU (ERI@N) Engineering::Materials Halide Perovskites Nanocrystals In the previous decade, a lot of research has been done in the area of halide perovskite materials which has led them to be used in all different typed of photonic applications. The low dimension crystals of this structure have also shown a lot of promise in quantum photonic devices. We synthesize perovskite Quantum Dots of composition Cs2PbSnI6 for photonic applications in Near Infra-red emission range. The atomic arrangement of B site cations in this composition dictates if the crystal structure thus formed would be a double perovskite (elpasolite) or not. All the elpasolites reported in literature have different oxidation states of the two cations at the B site (+1, +3) for example in Cs2AgBiBr6, where Ag is +1 and Bi is +3. But in our case, both the B site cations, Pb and Sn, are in +2 state. This increases the chances of having a disordered crystal structure where the B site cations do not follow any order. To verify the crystal structure a few different characterization methods can be used, such as X-Ray Diffraction (XRD) or Selected Area Electron Diffraction (SAED) in Transmission Electron Microscope (TEM). But the active perovskite phase, the black phase, is only metastable at room temperature, any action of air, moisture, electron beam and solvent can lead to phase transition to inactive (yellow) phase. Also, the low signal to noise ratio in XRD and EDX leads to inconclusive results in nanocrystals. Furthermore, the crystals formed were seen to be cubic in TEM and were always found to land on one of the facets. Since the crystal structure is also cubic, this led to presence of only (100) and (110) reflections and their multiples in both XRD and SAED patterns. The use of solvent also triggered coagulation of nanoparticles and formation of nanowires. Further the use of solvent also led to carbon contamination under electron beam. Due to a combined issue of all the degradation mechanisms, all the measurements were done in air-free conditions and the high-resolution TEM images and STEM-EDX was done in cryogenic conditions to slow down carbon contamination. The crystal structures of all possible arrangement of B site cations for both black and yellow phases were simulated using DFT. These structures were then used for Le-Bail refinement and refined with Rietveld refinement. These refined crystal structures were then used for matching with SAED ring pattern of ensemble of quantum dots. The resulting methodology for distinction between ordered and disordered structures can be extended to many more material systems. The possibility of 2-2 elpasolites mentioned in this work would help in the structure and properties of wide range of materials under the umbrella of Perovskites. 2023-08-14T07:22:41Z 2023-08-14T07:22:41Z 2023 Conference Paper Mishra, P., Zhang, M., Chen, A. P., Sum, T. C., Duchamp, M., Lam, Y. M. & Hippalgaonkar, K. (2023). Distinction between alloyed Perovskite and elpasolite nanocrystals. 20th International Microscopy Congress (IMC20). https://hdl.handle.net/10356/169883 https://www.imc20.kr/ en © 2023 IMC20 Local Organizing Committee. All rights reserved. application/pdf
institution Nanyang Technological University
building NTU Library
continent Asia
country Singapore
Singapore
content_provider NTU Library
collection DR-NTU
language English
topic Engineering::Materials
Halide Perovskites
Nanocrystals
spellingShingle Engineering::Materials
Halide Perovskites
Nanocrystals
Mishra, Pritish
Zhang, Mengyuan
Chen, Andy Paul
Sum, Tze Chien
Duchamp, Martial
Lam, Yeng Ming
Hippalgaonkar, Kedar
Distinction between alloyed Perovskite and elpasolite nanocrystals
description In the previous decade, a lot of research has been done in the area of halide perovskite materials which has led them to be used in all different typed of photonic applications. The low dimension crystals of this structure have also shown a lot of promise in quantum photonic devices. We synthesize perovskite Quantum Dots of composition Cs2PbSnI6 for photonic applications in Near Infra-red emission range. The atomic arrangement of B site cations in this composition dictates if the crystal structure thus formed would be a double perovskite (elpasolite) or not. All the elpasolites reported in literature have different oxidation states of the two cations at the B site (+1, +3) for example in Cs2AgBiBr6, where Ag is +1 and Bi is +3. But in our case, both the B site cations, Pb and Sn, are in +2 state. This increases the chances of having a disordered crystal structure where the B site cations do not follow any order. To verify the crystal structure a few different characterization methods can be used, such as X-Ray Diffraction (XRD) or Selected Area Electron Diffraction (SAED) in Transmission Electron Microscope (TEM). But the active perovskite phase, the black phase, is only metastable at room temperature, any action of air, moisture, electron beam and solvent can lead to phase transition to inactive (yellow) phase. Also, the low signal to noise ratio in XRD and EDX leads to inconclusive results in nanocrystals. Furthermore, the crystals formed were seen to be cubic in TEM and were always found to land on one of the facets. Since the crystal structure is also cubic, this led to presence of only (100) and (110) reflections and their multiples in both XRD and SAED patterns. The use of solvent also triggered coagulation of nanoparticles and formation of nanowires. Further the use of solvent also led to carbon contamination under electron beam. Due to a combined issue of all the degradation mechanisms, all the measurements were done in air-free conditions and the high-resolution TEM images and STEM-EDX was done in cryogenic conditions to slow down carbon contamination. The crystal structures of all possible arrangement of B site cations for both black and yellow phases were simulated using DFT. These structures were then used for Le-Bail refinement and refined with Rietveld refinement. These refined crystal structures were then used for matching with SAED ring pattern of ensemble of quantum dots. The resulting methodology for distinction between ordered and disordered structures can be extended to many more material systems. The possibility of 2-2 elpasolites mentioned in this work would help in the structure and properties of wide range of materials under the umbrella of Perovskites.
author2 Interdisciplinary Graduate School (IGS)
author_facet Interdisciplinary Graduate School (IGS)
Mishra, Pritish
Zhang, Mengyuan
Chen, Andy Paul
Sum, Tze Chien
Duchamp, Martial
Lam, Yeng Ming
Hippalgaonkar, Kedar
format Conference or Workshop Item
author Mishra, Pritish
Zhang, Mengyuan
Chen, Andy Paul
Sum, Tze Chien
Duchamp, Martial
Lam, Yeng Ming
Hippalgaonkar, Kedar
author_sort Mishra, Pritish
title Distinction between alloyed Perovskite and elpasolite nanocrystals
title_short Distinction between alloyed Perovskite and elpasolite nanocrystals
title_full Distinction between alloyed Perovskite and elpasolite nanocrystals
title_fullStr Distinction between alloyed Perovskite and elpasolite nanocrystals
title_full_unstemmed Distinction between alloyed Perovskite and elpasolite nanocrystals
title_sort distinction between alloyed perovskite and elpasolite nanocrystals
publishDate 2023
url https://hdl.handle.net/10356/169883
https://www.imc20.kr/
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